CLIAMS:CLAIMS
We Claim:

A method of optimizing power consumption of user equipment in wireless communication system, the method comprising steps of:
periodically exchanging control channel messages with a network during a same Transmission Time Interval (TTI) of Sounding Reference Signal (SRS) interval, wherein the control messages corresponds to Uplink (UL) and Downlink (DL) allocation and feedback messages;
determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange; and
entering into a sleep mode for the determined time duration till the next session of data exchange is initiated; and
wherein the TTI of the SRS interval corresponds to an active period of user equipment.

The method as claimed in claim 1, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
transmitting a SRS report to the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to a start of an ON duration time;
receiving an UL grant message in Physical Downlink Control Channel (PDCCH) from the network after expiry of first transmission time interval (TTI);
simultaneously sending a Channel Quality Indicator (CQI) report to the network at the same TTI in which the UL grant was received; and
entering into a sleep mode at a second TTI, wherein the UE is in a dynamic feedback mode.

The method as claimed in claim 2, wherein:
the first TTI corresponds to 4ms after the specific TTI; and
the second TTI corresponds to 8ms after the specific TTI.

The method as claimed in claim 2, wherein receiving the UL grant message in PDCCH from the network after the expiry of first TTTI comprises of:
allocating uplink resources to the user equipment in PDCCH channel by the network; and
sending, by the network, the UL grant message in PDCCH to the UE based on SRS measurements.

The method as claimed in claim 2, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
transmitting a UL data in Physical Uplink Shared Channel (PUSCH) to the network on allocated resources after the expiry of the second TTI of the DRX cycle;
simultaneously receiving a DL grant message and a DL data from the network at the same TTI in which the UL data was transmitted; and
Entering a sleep mode at a third TTI.

The method as claimed in claim 5, wherein the third TTI corresponds to 12ms after the specific TTI in which the SRS report was transmitted by the UE.

The method as claimed in claim 5, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval in the active period of the user equipment comprises of:
processing the received DL data for a third TTI;
transmitting a UL hybrid automatic repeat request (HARQ) feedback message to the network after the expiry of third TTI; and
simultaneously receiving DL HARQ feedback message in physical hybrid ARQ indicator channel (PHICH) from the network at the same TTI in which the UL HARQ feedback message was transmitted.

The method as claimed in claim 1, comprising:
re-transmitting, by the user equipment, the UL data when a negative acknowledgment (NACK) is received from the network; and
simultaneously receiving a retransmitted DL data upon sending a negative acknowledgment to the network.

The method as claimed in claim 1, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
receiving an UL grant message in PDCCH from the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to an ON duration time;
transmitting a CQI/SRS report for next SPS data along with SPS UL data to the network after expiry of first transmission time interval (TTI);
simultaneously receiving a SPS DL data from the network at the same TTI in which the UL data and CQI/SRS report was transmitted; and
entering into sleep mode for the second TTI, wherein the UE is in a semi static feedback mode.

The method as claimed in claim 9, wherein retransmission of UL and DL data is not required when the UE is in semi static feedback mode.

The method as claimed in claim 1, further comprising:
holding the transmission of CQI /SRS report to the network when the UE is in static feedback mode.
A method for minimizing CQI report in wireless communication system, the method comprising the steps of:
periodically receiving a CQI report from a user equipment;
determining whether a change in CQI value in the CQI report falls below a predefined threshold delta value of CQI at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SPS interval; and
triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the CQI falls below the predefined threshold delta value;
where the first mode corresponds to dynamic feedback mode and the second mode can correspond to either semi static feedback mode or static feedback mode.

The method as claimed in claim 12, further comprising:
determining whether change in ratio of acknowledgement (ACK) to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI;
triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK; and
restoring periodicity of CQI.wherein the first mode corresponds to a static feedback mode and the second mode is at least one of a semi static feedback mode or dynamic feedback reporting mode based on the TTI at which the change in ratio of ACK to NACK is measured.

The method as claimed in claim 13, further comprising:
computing CQI for wideband and sub bands, wherein the wideband has plurality of sub bands; and
deciding to communicate the CQI to the network if delta of CQI between subsequent wide bands is greater than threshold delta CQI and if delta of CQI between sub bands is not more than the threshold delta CQI.

A method for minimizing SRS report in wireless communication system, the method comprising the steps of:
determining whether a change in UL signal to noise ratio (SINR) value in the SRS report falls below a predefined threshold delta value of UL SINR at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SRS interval; and
triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the UL SINR falls below the predefined threshold delta value of UL SINR.
wherein the first mode corresponds to dynamic feedback reporting mode and the second mode corresponds to semi static feedback mode or static feedback mode based on the TTI at which the change in UL SINR is measured.

The method as claimed in claim 15, further comprising:
receiving SRS report from the UE in semi static feedback mode;
determining whether change in ratio of ACK to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI;
triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK; and
restoring periodicity of CQI;
wherein the first mode corresponds to a static feedback mode and the second mode can be either semi static feedback mode or dynamic feedback reporting mode based on the TTI at which the change in ratio of ACK to NACK is measured.

The method as claimed in claim 15, further comprising:
defining hysteresis values for uplink and downlink signaling in order to protect the UE from the temporarily fluctuating channel and from the overhead of UL and DL signaling;
comparing the values of change in CQI, change in UL SINR and change in ratio of ACK to NACK with the corresponding defined hysteresis values in the network; and
applying the corresponding reporting mode configuration on PDCCH in uplink and downlink based on the comparison.

The method as claimed in claim 15, further comprising:
monitoring ACK to NACK ratio to determine a change in a communication channel during a downlink data operation; and
periodically reporting CQI to the network when a change in the communication channel is determined.

The method as claimed in claim 15, further comprising:
adapting to dynamic changes in the communication channel for a defined layer three configurations for SRS and CQI by providing protection at physical layer level; and
defining a two bit binary numbers for reporting mode configuration at the PUCCH for uplink and PDCCH for downlink, wherein each two bit binary numbers correspond to a specific reporting configuration mode;
switching off a transmission chain of the UE when the UE is actively monitoring DL and there are no uplink transmissions, wherein the UE is in light sleep mode;
switching off both the transmission chain and receiving chain of the UE when the UE is not monitoring downlink and is transmitting on uplink, wherein radiofrequency (RF) and modem of the UE are in light sleep mode; and
switching off the RF and modem of the UE when the UE is not monitoring downlink or either transmitting in uplink, wherein the UE is in deep sleep mode.

The method as claimed in claim 19, wherein:
the DL data comprises of a VoLTE data and timing advance medium access control (MAC) protocol data unit (PDU); and
the UL data comprises of a VoLTE data and power head room reporting (PHR).

The method as claimed in claim 15, further comprising:
aligning periodicity of timing alignment (TA) PDU and power head room reporting (PHR) PDU with uplink and downlink allocation as per SPS interval, wherein the periodicity of TA and PHR PDU are integer multiple of SPS interval.

An user equipment configured for a wireless communication, comprising at least one means adapted for:
periodically exchanging control channel messages with a network during a same Transmission Time Interval (TTI) of Sounding Reference Signal (SRS) interval, wherein the control messages corresponds to Uplink (UL) and Downlink (DL) allocation and feedback messages;
determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange; and
entering into a sleep mode for the determined time duration till the next session of data exchange is initiated;
wherein the TTI of the SRS interval corresponds to an active period of user equipment.

The user equipment as claimed in claim 22, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
transmitting a SRS report to the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to a start of an ON duration time;
receiving an UL grant message in Physical Downlink Control Channel (PDCCH) from the network after expiry of first transmission time interval (TTI);
simultaneously sending a Channel Quality Indicator (CQI) report to the network at the same TTI in which the UL grant was received; and
entering into a sleep mode at a second TTI, wherein the UE is in a dynamic feedback mode.

The user equipment as claimed in claim 22, wherein:
the first transmission time interval corresponds to 4ms after the specific TTI; and
the second TTI corresponds to 8ms after the specific TTI.

The user equipment as claimed in claim 22, wherein receiving the UL grant message in PDCCH from the network after the expiry of first TTTI comprises of:
allocating uplink resources to the user equipment in PDCCH channel by the network; and
sending, by the network, the UL grant message in PDCCH to the UE based on SRS measurements.

The user equipment as claimed in claim 22, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
transmitting a UL data in Physical Uplink Shared Channel (PUSCH) to the network on allocated resources after the expiry of the second TTI of the DRX cycle;
simultaneously receiving a DL grant message and a DL data from the network at the same TTI in which the UL data was transmitted; and
entering a sleep mode at a third TTI;
wherein the third TTI corresponds to 12ms after the specific TTI in which the SRS report was transmitted by the UE.

The user equipment as claimed in claim 22, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval in the active period of the user equipment comprises of:
processing the received DL data for the third TTI;
transmitting a UL Hybrid Automatic Repeat Request (HARQ) feedback message to the network after the expiry of the third TTI; and
simultaneously receiving DL HARQ feedback message in physical hybrid ARQ indicator channel (PHICH) from the network at the same TTI in which the UL HARQ feedback message was transmitted.

The user equipment as claimed in claim 27, further comprising at least one means for:
re-transmitting, by the user equipment, the UL data when a negative acknowledgment (NACK) is received from the network; and
simultaneously receiving a retransmitted DL data upon sending a negative acknowledgment to the network.

The user equipment as claimed in claim 22, wherein periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of:
receiving an UL grant message in PDCCH from the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to an ON duration time;
transmitting a CQI/SRS report for next Semi Persistence Scheduling (SPS) data along with SPS UL data to the network after expiry of first transmission time interval (TTI);
simultaneously receiving a SPS DL data from the network at the same TTI in which the UL data and CQI/SRS report was transmitted; and
entering into sleep mode for the second TTI, wherein the UE is in a semi static feedback mode.

Dated this the 3rd day of February 2015

Signature
KEERTHI J S
Patent agent
Agent for the applicant

,TagSPECI:
FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

METHOD AND SYSTEM FOR PROVIDING POWER OPTIMIZATION OF USER EQUIPMENTS IN CONNECTED MODE IN WIRELESS COMMUNICATION SYSTEMS

SAMSUNG R&D INSTITUTE INDIA – BANGALORE Pvt. Ltd.
# 2870, ORION Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanakundi Circle,
Marathahalli Post,
Bangalore -560037, Karnataka, India
Indian Company

The following Specification particularly describes the invention and the method it is being performed
FIELD OF THE INVNENTION
The present invention relates to wireless communication systems and more particularly to a system and method for power optimization of user equipment’s in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

BACKGROUND OF THE INVENTION
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems aims at providing higher data rates and lower latencies to the customers that can make wireless mobile devices a great platform to run a new whole set of services and applications. One of the key objectives to support this evolution is the improved efficiency of power utilization: LTE exploits the idea of Discontinuous Reception (DRX) and Discontinuous Transmission (DTX). The DRX cycle consists of an ‘On Duration’ during which the user equipment (UE) should monitor the Physical Downlink Control Channel (PDCCH) and a ‘DRX period’ during which a UE can skip reception of downlink channels for battery saving purposes. The DRX cycle specifies the periodic repetition of the ON duration followed by a possible period of inactivity.

In current system deployment, 3GPP has put substantial focus to minimize the power consumption in connected mode of operation of wireless communication system. As research efforts, multiple solution like connected mode DRX and Semi persistence solution has been proposed (36.321). Connected mode DRX is an elegant solution of reduce power consumption, which find the optimal trade off to wakes up the UE only at the time, when, there is some data is schedule. Connected mode DRX, when used, in conjunction with Semi persistence scheduling (SPS) provides further gain and avoid waking up UE, to read control channel for downlink (DL)/uplink (UL) resource allocation, since SPS pre-defines the assignment with SPS interval. However, unaligned nature of allocation/feedback can force UE to wake up and read the allocation or send feedback information. This would eat substantial gain achieved by the connected mode DRX design. Further, the main point of this functionality makes the terminal to not monitor the control channels continuously, but only in well-defined instants, turning the radiofrequency (RF) modem in a sleep state as much as possible. In fact, control data are low-frequency and low bit-rate, so continuous listening the related channels represents a big waste of power resource.

Therefore, there exists a need to provide a system and method for power optimization of user equipments in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent upon a reading of the specification and a study of the drawings.

SUMMARY OFTHE INVENTION
The various embodiments herein provide a method for optimizing power consumption of user equipment in wireless communication system. The method comprising steps of periodically exchanging control channel messages with a network during a same Transmission Time Interval (TTI) of Sounding Reference Signal (SRS) interval, wherein the control messages corresponds to Uplink (UL) and Downlink (DL) allocation and feedback messages, determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange and entering into a sleep mode for the determined time duration till the next session of data exchange is initiated.

According to an embodiment herein, TTI of the SRS interval corresponds to an active period of user equipment.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a SRS report to the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to a start of an ON duration time, receiving an UL grant message in Physical Downlink Control Channel (PDCCH) from the network after expiry of first transmission time interval (TTI), simultaneously sending a Channel Quality Indicator (CQI) report to the network at the same TTI in which the UL grant was received and entering into a sleep mode at a second TTI, wherein the UE is in a dynamic feedback mode.

According to an embodiment herein, the first transmission time interval corresponds to 4ms after the specific TTI and the second TTI corresponds to 8ms after the specific TTI.

According to an embodiment herein, receiving the UL grant message in PDCCH from the network after the expiry of first TTTI comprises of allocating uplink resources to the user equipment in PDCCH channel by the network and sending, by the network, the UL grant message in PDCCH to the UE based on SRS measurements.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a UL data in Physical Uplink Shared Channel (PUSCH) to the network on allocated resources after the expiry of the second TTI of the DRX cycle, simultaneously receiving a DL grant message and a DL data from the network at the same TTI in which the UL data was transmitted and entering a sleep mode at a third TTI.
According to an embodiment herein, the third TTI corresponds to 12ms after the specific TTI in which the SRS report was transmitted by the UE.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval in the active period of the user equipment comprises of processing the received DL data for a third TTI, transmitting a UL hybrid automatic repeat request (HARQ) feedback message to the network after the expiry of third TTI and simultaneously receiving DL HARQ feedback message in physical hybrid ARQ indicator channel (PHICH) from the network at the same TTI in which the UL HARQ feedback message was transmitted.

According to an embodiment herein, the method further comprises of re-transmitting, by the user equipment, the UL data when a negative acknowledgment (NACK) is received from the network and simultaneously receiving a retransmitted DL data upon sending a negative acknowledgment to the network.

According to an embodiment herein, entering into a sleep mode for the determined time duration till the next session of data exchange is initiated comprises of switching off radio frequency and baseband processor for optimal power optimization.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of receiving an UL grant message in PDCCH from the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to an ON duration time, transmitting a CQI/SRS report for next SPS data along with SPS UL data to the network after expiry of first transmission time interval (TTI), simultaneously receiving a SPS DL data from the network at the same TTI in which the UL data and CQI/SRS report was transmitted and entering into sleep mode for the second TTI, wherein the UE is in a semi static feedback mode.

According to an embodiment herein, retransmission of UL and DL data is not required when the UE is in semi static feedback mode.

According to an embodiment herein, the method further comprises of holding the transmission of CQI /SRS report to the network when the UE is in static feedback mode.

Embodiments herein further disclose a method for minimizing CQI report in wireless communication system, the method comprising the steps of periodically receiving a CQI report from a user equipment, determining whether a change in CQI value in the CQI report falls below a predefined threshold delta value of CQI at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SPS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the CQI falls below the predefined threshold delta value.

According to an embodiment herein, the first mode corresponds to dynamic feedback mode and the second mode corresponds to either semi static feedback mode or static feedback mode.

According to an embodiment herein, the method further comprises of determining whether change in ratio of acknowledgement (ACK) to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the first mode corresponds to a static feedback mode and the second mode is at least one of a semi static feedback mode or dynamic feedback reporting mode based on the TTI at which the change in ratio of ACK to NACK is measured.

According to an embodiment herein, the method further comprising computing CQI for wideband and sub bands, wherein the wideband has plurality of sub bands and deciding to communicate the CQI to the network if delta of CQI between subsequent wide bands is greater than threshold delta CQI and if delta of CQI between sub bands is not more than the threshold delta CQI.

Embodiments herein further disclose a method for minimizing SRS report in wireless communication system, the method comprising the steps of determining whether a change in UL signal to noise ratio (SINR) value in the SRS report falls below a predefined threshold delta value of UL SINR at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SRS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the UL SINR falls below the predefined threshold delta value of UL SINR.

According to an embodiment herein, the method further comprises of receiving SRS report from the UE in semi static feedback mode, determining whether change in ratio of ACK to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the method further comprises of defining hysteresis values for uplink and downlink signaling in order to protect the UE from the temporarily fluctuating channel and from the overhead of UL and DL signaling, comparing the values of change in CQI, change in UL SINR and change in ratio of ACK to NACK with the corresponding defined hysteresis values in the network and applying the corresponding reporting mode configuration on PDCCH in uplink and downlink based on the comparison.

According to an embodiment herein, further comprising monitoring ACK to NACK ratio to determine a change in a communication channel during a downlink data operation and periodically reporting CQI to the network when a change in the communication channel is determined.

According to an embodiment herein, the method further comprises of adapting to dynamic changes in the communication channel for a defined layer three configurations for SRS and CQI by providing protection at physical layer level and defining a two bit binary numbers for reporting mode configuration at the PUCCH for uplink and PDCCH for downlink, wherein each two bit binary numbers correspond to a specific reporting configuration mode.

According to an embodiment herein, the UE is actively monitoring downlink and is transmitting on the uplink.

According to an embodiment herein, switching off a transmission chain of the UE when the UE is actively monitoring DL and there are no uplink transmissions, wherein the UE is in light sleep mode.

According to an embodiment herein, the method further comprises of switching off both the transmission chain and receiving chain of the UE when the UE is not monitoring downlink and is transmitting on uplink, wherein radiofrequency (RF) and modem of the UE are in light sleep mode and switching off the RF and modem of the UE when the UE is not monitoring downlink or either transmitting in uplink, wherein the UE is in deep sleep mode.

According to an embodiment herein, the DL data comprises of a VoLTE data and timing advance medium access control (MAC) protocol data unit (PDU) and the UL data comprises of a VoLTE data and power head room reporting (PHR).

According to an embodiment herein, the method further comprises of aligning periodicity of timing alignment (TA) PDU and power head room reporting (PHR) PDU with uplink and downlink allocation as per SPS interval, wherein the periodicity of TA and PHR PDU are integer multiple of SPS interval.

Embodiments herein further disclose a user equipment, a wireless terminal and a non-transitory computer readable medium having a processor operable to perform the aforementioned method in collaboration.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a graphical representation of a Semi persistence scheduling (SPS) downlink packet drop probability in a single user scenario, according to an embodiment of the present invention.

Figure 2 is a schematic representation of data transfer operation of the UE where the UE is kept alive for long duration due to which there is an increase in the power consumption, according to a prior art.

Figure 3a is a timing diagram representing a common SPS transmission time interval (TTI) for UL and DL data, where the interval for SPS UL/DL and the interval for CQI/SRS is same, according to an embodiment of the present invention.

Figure 3b is a timing diagram representing a common SPS TTI for getting SPS UL/DL data and CQI/SRS, according to an embodiment of the present invention.

Figure 4a is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 4b is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL with HARQ retransmission, according to an embodiment of the present invention.

Figure 5 is a schematic representation of data transfer operation of the UE in semi static feedback reporting mode where CQI/SRS is having the same TTO as that of SPS UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 6 is a schematic representation of a wideband having N sub bands along with the computed CQI value, according to an embodiment of the present invention.

Figure 7 is a timing diagram for a reporting mode configuration in downlink, according to an embodiment of the present invention.

Figure 8 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for downlink, according to an embodiment of the present invention.

Figure 9 is a timing diagram of a reporting mode configuration in uplink, according to an embodiment of the present invention.

Figure 10 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for uplink, according to an embodiment of the present invention.

Figure 11 is a system diagram illustrating an exemplary wireless communication system, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others, this is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a system and method for power optimization of user equipment’s in connected mode in wireless communication systems. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

In a peer to peer conversation, there are there are several modes in which conversation can be classified as Discussion, Talking or Listening. One can always save power by switching uplink (UL)/downlink (DL) either or both ON or OFF, during various phases of conversation. In ‘talking’ mode of conversation, caller is continuously talking and peer entity is listening. Thus caller always need UL grants to send the data. In talking mode of operation, Caller should monitor PDCCH in downlink to receive UL allocation. The UE 1102 has to transmit sounding reference signal (SRS) for the purpose of enode B (eNB) 1104 UL channel state information (CSI) measurement. So that eNB 1104 can allocate the suitable UL resources to the UE 1102. However, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) medium access control (MAC) protocol data unit (PDU). This requires resources in the downlink on Physical Downlink Shared Channel (PDSCH). The UL acknowledgment/ negative acknowledgement (ACK/NACK) and CSI either send by Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH). The UE 1102 also keeps reporting PHR (power head room report) as the difference between MAX UE 1102 transmission (Tx) power and estimated Tx power on UL shared channel (SCH). This will also call for UL resources allocation.
Generally, all uplink channel (PUCCH, PUSCH, and SRS) and DL (PDCCH, PDSCH, and physical hybrid ARQ indicator channel (PHICH)) are in constant use during talking operation. In case of talking mode operation, to minimize the power, the present invention provides a method to align uplink and downlink course of operation.
In ‘listening’ mode of conversation, caller is continuously listening and peer entity is talking. Thus caller always need DL resources to receive the data. During listening mode of operation, UE 1102 needs to read PDCCH for the resource allocation on PDSCH. The UE 1102 also, have to measure the Reference signals in downlink and send CSI feedback in UL, in order to provide link adaptation and resource allocation in downlink and also, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) MAC PDU on PDSCH. This requires resources in the downlink on PDSCH. The UL ACK/NACK and CSI either send by PUSCH or PUCCH. UE 1102 also keep reporting PHR (power head room report) as the difference between MAX UE 1102 TX power and estimated Tx power on UL SCH. This will also call for UL resources allocation.
Generally, PUCCH, PUSCH and DL (PDCCH, PDSCH and PHICH) are in constant use during listening operation. In listening mode of operation, easy way to minimize the power is to align uplink and downlink course of operation and to minimize the periodicity of SRS transmission. A Caller can indicate the “listening” mode to network 1104 by using the toggle bit in PDCCH.
Figure 1 is a graphical representation of a SPS downlink packet drop probability in a single user scenario, according to an embodiment of the present invention. According to an embodiment of the present invention, SPS interval is considered to be 40ms for all the scenarios mentioned herein (voice CODEC generates the data every 20ms). Therefore, the UE 1102 and the enode B 1104 has to buffer the data until SPS interval and has to send the whole data as a single burst at the Semi persistence scheduling (SPS) transmission time interval (TTI). This saves UE 1102 power as UE 1102 can go to DRX for long time. For example, in case of large SPS (or DRX) intervals like 60ms and above, the delay is more and hence UE 1102 suffer from packet loss in DL, which is evident in Figure 1.

There can be four scenarios or modes in which UE 1102 goes to sleep and save power. In the first scenario which is in RRC connected mode (also referred as power state 1), the UE 1102 is actively monitoring DL and is also transmitting on the UL. In the second scenario which is also on RRC connected mode (also referred as power state 2), the UE 1102 is actively monitoring DL but there are no uplink transmissions (TX chain). Hence, the TX chain is turned off in this state. In the third scenario which is a light sleep mode (also referred as power state 3), the UE 1102 is not monitoring DL or transmitting on UL. Both the receive (Rx) and transmit (Tx) are turned off. The modem and RF are put in “light sleep mode”. In the last scenario which is a deep sleep mode (also referred as power state four), the UE 1102 is not monitoring DL or transmitting on UL. RF and modem are both shut down. The only modem power consumption is due to leakage.

Figure 2 is a schematic representation of data transfer operation of the UE 1102 where the UE 1102 is kept alive for long duration due to which there is an increase in the power consumption, according to a prior art. One of the major problems for more power consumption in UE 1102 can be the dis-aligned pattern of resource allocation for UL and DL, also dis-aligned reporting of channel quality indicator (CQI) and SRS. Thus it can be overcome by some mechanism which can align the resource allocation and CQI/SRS reporting. Figure 2 shows how the UE 1102 will keep alive for long duration due to which power consumption will increase. It shows that UE 1102 is consuming power for more than half of DRX cycle in worst case scenario. Thus to overcome this problem, the present invention provides a method to align the resource allocation and CQI/SRS reporting. This would provide sufficient time for UE 1102 for micro sleep.

Figure 3a is a timing diagram representing a common SPS TTI for UL and DL data, where the interval for SPS UL/DL and the interval for CQI/SRS is same, according to an embodiment of the present invention. According to an embodiment of the present invention, power consumption can be reduced if the SPS configuration for data Transmission in UL and DL interval is same and align in the same TTI. The UE 1102 can wake up only at that SPS intervals and can go to light sleep mode for remaining period of time as connected mode DRX. This saves the UE 1102 power largely. If the CQI and SRS reporting are also configured at the same periodicity of the SPS interval, then the UE 1102 can send CQI/SRS in active time and UE 1102 does not have to wake up separately in other TTI’s to report CQI and SRS. Figure 3a shows that the SPS TTI for UL and DL is same, the interval for the SPS UL/DL and the interval for the CQI/SRS is same.

Figure 3b is a timing diagram representing a common SPS TTI for getting SPS UL/DL data and CQI/SRS, according to an embodiment of the present invention. Figure 3b shows that the TTI to get SPS UL/DL data and CQI/SRS report is same, i.e., both the SPS UL/DL data transmission and CQI/SRS reporting occurs in active time, but that may or may not be same TTI. So, the UE 1102 need not wake up separately for the reporting and data transmission. This saves UE 1102 power by shutting down the baseband and RF processor. Based on the UE 1102 capability, UE 1102 can opt to go in light sleep for either UL/DL or both UE 1102.

According to an embodiment of the present invention, if the SPS TTI for UL and DL are same, then the UE 1102 can wake-up for 1 TTI to get DL and UL resource allocation and ACK/NACK through PDCCH and PUCCH. Further, the UE 1102 has to piggy back the CQI/SRS as it cannot be reported along with ACK/NACK.

In SPS based operation, since the TTI in which UE 1102 receives grant is already known, the UE 1102 does not have to monitor PDCCH, neither in on duration timer or inactivity timer. So, for VOLTE operation ON duration timer can be reduced to 1 TTI and inactivity timer can be removed. In case of successful transmission of UL data, ACK is received. However in case of re-transmission, UL data can be sent in next immediate TTI in which NACK has to be received.

As a normal course of operation, the UE 1102 decodes DL data in the same TTI, in which it gets PDCCH grant. However for uplink, UE 1102 receives grant in nth TTI for the transmission on PUSCH on n+4 (TTI). For both DL and UL operation, ACK, NACK comes after 4ms, which is a processing time. UE 1102 /eNB 1104 takes another 4ms for the Re-transmission or the transmission of new packet.

In order to allocate resources on UL or DL, the UE 1102 should measure the CSI in downlink and send CQI after n+4 TTI on PUCCH. Similarly, for UL, SRS should be transmitted by UE 1102 to get resources for uplink with the configured periodicity. Since it’s a SPS based scheduling, UE 1102 does not have to send SR on PUCCH. Moreover, to keep the UE 1102 in UL sync, eNB 1104 has to keep sending MAC PDU in downlink and Power headroom reporting should be done in uplink, which requires more PUSCH resources.

In an embodiment of the present invention, the UE 1102 sends CQI report and SRS signal within the active time without waking up separately. So, the UE 1102 is active for very less time within DRX cycle, which saves the UE 1102 power largely. When there is no data in UL and DL, UE 1102 makes the RF switch off (light sleep), which saves the UE 1102 power.

According to an embodiment of the present invention, SPS downlink data in PDSCH consists of the VOLTE data and the timing advanced MAC PDU. However, SPS uplink data in PUSCH consists of volte data and power head room reporting.

In the present invention, periodicity of Timing alignment PDU and power head room reporting PDU are aligned with UL and DL allocation as per SPS interval i.e. Periodicity of TA and PHR PDU should be in integer multiple of SPS interval.

The present invention defines three modes of operation for the UE 1102 based on the channel, namely, dynamic feedback reporting mode, semi static feedback reporting mode and static feedback reporting mode.

Figure 4a is a schematic representation of data transfer operation of the UE 1102 in dynamic feedback reporting mode having same SPS TTI for UL and DL without HARQ retransmission, according to an embodiment of the present invention. According to Figure 4, a SRS report is sent from UE 1102 at the ‘N’th TTI of the DRX cycle, which is start of the on duration time. The UL grant comes after 4ms, which is N+4 TTI. In order to optimize the UL transmission, UE 1102 sends the CQI report at the N+4 TTI. In this embodiment, it is assumed that the UE 1102 measures the SINR for 4 TTI’s and derives CQI which is sent in the N+4 TTI.

FN * DRX_CYCLE (4) +1 => SRS
FN * DRX_CYCLE (4) +5 => SPS UL grant / CQI report
FN * DRX_CYCLE (4) +9 => SPS DL data / SPS UL data
FN * DRX_CYCLE (4) +13 => DL / UL HARQ ACK/NACK
FN * DRX_CYCLE (4) +17 => SPS DL / UL Data Re RX / TX
FN * DRX_CYCLE (4) +21 => DL / UL HARQ ACK for Re TX / RX

In an embodiment of the present invention, the ENodeB 1104 measures the channel on sounding reference signals i.e., SRS and allocates the UL resources to UE 1102 by PDDCH. The ENodeB 1104 sends UL grant in PDCCH in N+4 TTI based on the SRS measurements and the UE 1102 sends the UL transmit data on the allocated resources in N+8 TTI. After receiving the grant on PDCCH, the UE 1102 takes 4ms of processing time before sending the UL data on PUSCH.

After CQI report has been sent from UE 1102 in PUSCH, the eNodeB 1104 takes 4ms to send the DL grant in PDCCH and DL data in PDSCH. So, at the N+8 TTI, the UE 1102 transmits UL data in PUSCH and also receives the DL grant (and DL data) in PDCCH (in PDSCH). After receiving the DL data in PDSCH, the UE 1102 takes 4ms to process and send UL HARQ feedback. At the same time, eNodeB 1104 will also take 4ms to process the received data and sends the DL HARQ feedback in the PHICH. So, as per the present invention, at N+12 TTI, UE 1102 sends UL HARQ feedback and also receives the DL HARQ feedback.

Figure 4b is a schematic representation of data transfer operation of the UE 1102 in dynamic feedback reporting mode having same SPS TTI for UL and DL with HARQ retransmission, according to an embodiment of the present invention. In case of re-transmission, the UE 1102 re-transmits UL data at N+16 TTI. However, the eNodeB 1104 can also re-send DL data at N+16 TTI. The UE 1102 takes 4 TTI to process the DL data and send the UL HARQ ACK at N+20 TTI. Similarly, the eNodeB 1104 also processes the UL data and sends the DL HARQ ACK at N+20 TTI. Hence, the TX and RX operation is aligned in such a way, so that the UE 1102 can utilize the maximum time of DRX operation in sleep and consequently the UE 1102 can shut down the RF and baseband processor for optimal power optimization.

Figure 5 is a schematic representation of data transfer operation of the UE 1102 in semi static feedback reporting mode where CQI/SRS is having the same TTO as that of SPS UL and DL without HARQ retransmission, according to an embodiment of the present invention. When channel is considered to be largely static then periodicity of UE 1102 feedback can be minimized and reported UE 1102 feedback can be used for the SPS after DRX cycle. It can be identified by examining the toggle bit in PUCCH. In order to reduce the UE 1102 wake-up time, the CQI/SRS interval and UL/DL SPS interval are aligned within the same TTI in active time. In this scenario, CQI report, SRS, UL data transmission and reception of DL data happens in same TTI. So, the UE 1102 goes to light sleep until DL HARQ feedback comes on PHICH and UL HARQ feedback is ready to be sent in PUCCH. As shown in the Figure 5, in Nth TTI of DRX cycle the UE 1102 receives the SPS UL grant and starts preparing the UL data. The UL and DL grants are sent by the network 1104 depending upon CQI/SRS report received in previous DRX cycle. The UE 1102 starts measuring the SINR to report CQI at N+4 TTI. The UE 1102 sends UL data and receives DL data in same TTI, which is N+ 4 TTI of DRX cycles, which is also SPS TTI, configured for UL and DL data.

If UE 1102 schedules the CQI and SRS reporting in the same TTI, then the UE 1102 can sleep in other TTI’s, which saves UE 1102 power more. Here, the CQI/SRS report sent is used for resource allocation of UL and DL for the next SPS interval. So, the active time in DRX cycle is less and the UE 1102 wakeup time is only 2TTI’s in active time and the remaining TTI’s UE 1102 goes to light sleep.

In static feedback reporting mode, where user is either stationary or with very limited mobility, the channel is assumed to be largely stationary and CQI/SRS measurements are least expected to be change. This can be leveraged in the power optimization of VOLTE design. The UE 1102 can minimize or avoid the transmission of CQI/SRS (under, periodicity, which is, configured by L3 signaling) and hence can save the power, which is required to report CQI and in sending SRS to measure UL channel state information. The table below depicts the relation between CQI and modulation:

CQI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Modulation QPSK QPSK QPSK QPSK QPSK QPSK 16QAM 16Q
AM 16QAM 64QAM 64QAM 64QAM 64QAM 64QAM 64QAM
MCS 0 0 2 5 7 9 12 14 16 20 23 25 27 28 28

Figure 6 is a schematic representation of a wideband having N sub bands along with the computed CQI value, according to an embodiment of the present invention. By observing the pattern of computed CQI value, the UE 1102 can decide on communicating the CQI to eNodeB 1104. The UE 1102 has to check the CQI variation between subsequent sub-bands and also CQI variation across transmission TTI as per periodicity configured by layer-3. In Figure 6, where the wide band has ‘N’ sub bands (in this fig, wide band have 4 sub bands), the UE 1102 computes the CQI for wide band as CQI(?WB?_t) and also computes CQI for subbands of this wide band. The UE 1102 then decides to communicate the CQI to eNodeB 1104, only if the delta of CQI between subsequent wide bands is greater that threshold delta ‘?CQI?_D’, along with this the UE 1102 also checks that the delta of CQI between sub bands should not be more than threshold delta? CQI?_d.

Thus, UE 1102 communicates CQI if and only of,
CQI(?WB?_(t+1) )-CQI(?WB?_t )>?CQI?_(D ) 1
CQI(?SB?_(t+1)^i )-CQI(?SB?_t^i )>?CQI?_d 2
? t where in t=1 to N_TTI And i is the ith subband in bandwith

The UE 1102 keeps measuring and keeps reporting CQI during the connected mode of operation consequently network 1104 and allocates MCS.

Figure 7 is a timing diagram for a reporting mode configuration in downlink, according to an embodiment of the present invention. According to Figure 7, the UE 1102 measures the SINR on the wideband /Sub band RS and sends the measured wideband /Sub band CQI report to eNB 1104 as per figure 4a and 4b. The enodeB (eNB) 1104 then monitors the CQI variation for consecutive N_TTI. In case, if change in CQI, falls below CQI_d then the eNb 1104 triggers to change the reporting mode configuration to “semi static feedback mode: 01” via PDCCH. After receiving the reporting mode configuration, the UE 1102 sends the CQI report (as per figure 5) regardless of configured CQI periodicity in layer 3 message. The eNb 1104 will further monitor the CQI variation for consecutive M x N_TTI. In case, if change in CQI falls below CQI_d, then the eNb 1104 sends trigger to change the reporting mode configuration to “static feedback mode: 10”, wherein M is defined as number of cycles for N_TTI. After changing reporting mode from “Dynamic feedback mode” to any other feedback mode, the eNb 1104 starts monitoring ACK/NACK ratio at the eNB 1104 for UE 1102. As long as, change in ratio of ACK/NACK remains less than ?Ratio_(ack/nack_DL )wherein, ??Ratio?_(ack/nack_DL )is measured for? N?_TTI. , the eNb 1104 allocates SPS and feedback allocation according to figure 4a/4b or figure 5. As soon as, change in ratio of ACK/NACK becomes greater than (or equal to) ?Ratio_(ack/nack_DL ), then eNB 1104 informs UE 1102 via PDCCH to change the reporting mode to “semi static feedback mode : 01” by below given protocol structure. The change in ratio of ACK/NACK is observed incrementally for N_(MeasInterval_dl)^ . If ACK/NACK ratio is found to be changing greater than ?Ratio_(ack/nack_DL ) then, the reporting mode is changed to dynamic reporting and periodicity of CQI is restored as configured by Layer3 configuration.

Thus, the CQI reporting is minimized which is useful in stationary UE 1102’s. (If CQI is not received from UE 1102 before 4 TTI’s from SPS DL interval, the network 1104 decides that CQI is not changed and will allocate the previous resources for DL data).

Figure 8 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for downlink, according to an embodiment of the present invention. At step 802, SPS UL/DL grant, CQI, SRS, DL/UL HARQ, ACK/NACK is aligned in a dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel. At step 804, change in CQI is measured for N_TTI. At step 806, it is determined whether the change in CQI falls below ?CQI?_d and hysteresis for ?CQI?_(d_hys). If yes, then at step 808, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned (as per figure 5), in a semi static feedback reporting mode. The enode B 1104 changes configuration mode by PDCCH or downlink common control channel. If the change in CQI does not fall below ?CQI?_d and hysteresis for ?CQI?_(d_hys), then the process is transferred to step 804. At step 810, change in CQI is measured for M x N_TTI. At step 812, it is checked whether the change in CQI falls below ?CQI?_d and hysteresis for ?CQI?_(d_hys). If so, then at step 814, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned in a static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. On the other hand, if the change in CQI does not fall below ?CQI?_d and hysteresis for ?CQI?_(d_hys), then the process is transferred to step 810. At step 816, the ACK/NACK ratio is constantly measured by eNB 1104. At step 818, it is determined whether a change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_DL) and hysteresis for ??Ratio?_(ack/nack_DL_hys). If yes, then the process is transferred to step 816. If not, then at step 820, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned in a semi static feedback reporting mode. The enB 1104 changes configuraiton mode by PDCCH or downlink common control channel. At step 822, changes in ACK/NACK ratio are measured for N_(MeasInterval_dl). At step 824, it checked whether change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_DL) and hysteresis for ??Ratio?_(ack/nack_DL_hys). If yes, then the process is transferred back to step 816. If no, then at step 826, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned back in dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel.

Figure 9 is a timing diagram of a reporting mode configuration in uplink, according to an embodiment of the present invention. According to Figure 9, the eNB 1104 measures the UL SINR on SRS and allocates UL physical resource allocation for the purpose of channel adaptation in UL. The eNB 1104 monitors the UL SINR on SRS for consecutive N_TTI. In case, if change in UL SINR falls below ?UL_?SINR?_d then eNb 1104 triggers to change the reporting mode configuration to “semi static feedback mode: 01” via PDCCH. The eNB 1104 further monitors the UL SINR variation for consecutive M x N_TTI. If change in UL SINR falls below ?UL_?SINR?_d then, the eNB 1104 triggers to change the reporting mode configuration to “static feedback mode: 10” wherein, M is defined as number of N_TTI cycles. Otherwise, the eNB 1104 keeps operating in the configured operating mode. The SRS is transmitted by the UE 1102 as defined in Fig 4.a /4.b and Fig-5 respectively for “semi static feedback” reporting. After changing reporting mode from – “Dynamic feedback mode” to any other feedback mode, the eNB 1104 monitors ACK/NACK ratio at the eNB 1104 for UE 1102. As long as, change in ratio of ACK/NACK remains less than ??Ratio?_(ack/nack_uL )wherein, ??Ratio?_(ack/nack_uL )is measured for N_TTI, the eNB 1104 allocates the UL SPS allocation and feedback allocation according to fig 4a/4b or fig -5. As soon as, change in ratio of ACK/NACK becomes greater then (or equal to) ??Ratio?_(ack/nack_uL ), then eNb 1104 informs to UE 1102 via PDCCH to change the reporting mode to “semi static feedback mode : 01” by below given protocol structure. The change in ratio of ACK/NACK is observed incrementally for N_(MeasInterval_dl)^ . If ACK/NACK ratio is found to be changing and is greater than ??Ratio?_(ack/nack_uL ) then, the reporting mode is changed to dynamic reporting and periodicity of CQI is restored as configured by Layer3 configuration.

According to an embodiment of the present invention, if ??Ratio?_(ack/nack_UL ), ??Ratio?_(ack/nack_DL ) , ?CQI?_d,?UL_?SINR?_d are left unbound then, the UE 1102 might suffer from the overhead of UL and DL signaling, especially where channel is fluctuating temporarily. This would consume all the gains, which were accrued by virtue of proposed UL ad DL control singling to reduce the UL control transmission. In order to protect the temporarily fluctuation an additional Hysteresis say ??Ratio?_(ack/nack_UL_hys ) and ??Ratio?_(ack/nack_DL_hys ), ?CQI?_(d_hys),?UL_?SINR?_(d_hys) could be added, which does not allow to trigger the UL and DL control channel signaling with instantaneous channel changes. As in implementation,

For Uplink,
??Ratio?_(ack/nack_UL ) in Uplink and ACK /NACK ratio becomes greater than ??Ratio?_(ack/nack_DL ) in downlink then, the reporting mode configuration is applied on PDCCH only, if change in UL_SINR measured is greater than ?UL_?SINR?_(d_hys) for consecutive ?NTTI?_(ul_Hys) . Further, the reporting mode configuration is also applied on PDCCH only, if ACK/NACK ratio is measured greater than ??Ratio?_(ack/nack_UL_hys )for consecutive ?NTTI?_(ul_Hys) .

For downlink, the reporting mode configuration is applied on PDCCH only if change in CQI measured is greater than ?CQI?_(d_hys)for consecutive ?NTTI?_(Dl_Hys) . Further, the reporting mode configuration is applied on PDCCH only if ACK/NACK ratio is measured greater than ??Ratio?_(ack/nack_DL_hys )for consecutive ?NTTI?_(Dl_Hys) .

In case of DL data operation, the CQI reporting mode, as in current ART is configured by the higher layer and is not expected to be changed per TTI or per “X” TTI where in X>1 . As per present invention, the UE 1102 is expected to report the CQI even though channel is static or quasi static, where in, change in channel, has very minimum impact on BLER and in worst case, the same is protected by HARQ at the cost of re-transmissions.

In case of UL data operation, the SRS is transmitted as per the configured periodicity by Layer-3 configuration as in current ART. However, the disadvantage is that, it fails to handle the dynamic changes in the channel, which can add significant value, especially where fix allocation and periodic grants are required. The present invention provides additional protection at physical layer level to combat with the dynamic changes in the channel for a given layer 3 configurations for SRS and CQI. The reporting mode can be configured by 2 bit at the PUCCH for UL and PDCCH for DL, wherein 4 configuration modes are possible.

UL/DL configuration mode
0: Uplink
1: Downlink
00 – Dynamic feedback reporting mode
01 – Semi static feedback reporting mode.
10 – Static feedback reporting mode.
11- Reserved.

For a given periodicity, as configured by the RRC signaling, the UE 1102 is configured in below given mode by PDCCH.

Figure 10 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for uplink, according to an embodiment of the present invention. at step 1002, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 4.a and 4.b in a dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel. At step 1004, change in ??UL_SINR?_d for N_TTI is measured. At step 1006, it is checked whether change in UL_SINR falls below ??UL_SINR?_d and hysteresis for ??UL_SINR?_(d_hys). If no, then the process is transferred back to step 1004. If yes, then at step 1008, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned (as per figure 5), in a semi static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1010, change in UL_SINR for M x? N?_TTI is measured. At step 1012, it is checked whether change in UL_SINR falls below ??UL_SINR?_d and hysteresis for ??UL_SINR?_(d_hys). If no, then the process is transferred back to step 1010. If yes, then at step 1014, SPS UL/DL grant CQI SRS, DL/UL HARQ ACK/NACK are aligned as per figure 6, in a static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1016, the ACk/NACK ratio is constantly measured by the eNB 1104. At step 1018, it is checked whether the change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_uL ) and hysteresis for ??Ratio?_(ack/nack_UL_hys ). If yes, then the process is transferred back to step 1016. If no, then at step 1020, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 5, in a semi static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1022, changes in ACK/NACK ratio are measured for N_(MeasInterval_dl). At step 1024, it is checked whether change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_uL ) and hysteresis for ??Ratio?_(ack/nack_UL_hys ). If yes, then the process is transferred back to step 1016. If no, then at step 1026, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 4.a and 4.b, back in the dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel.

Figure 11 is a system diagram illustrating an exemplary wireless communication system, according to an embodiment of the present invention. The wireless communication system 1100 comprises of user equipment 1102 and a network 1104. The UE 1102 communicates with the network 1104 through a wireless communication medium 1106. The UE 1102 comprises of a SPS alignment module 1108. The SPS alignment module 1108 is configured for periodically exchanging control channel messages with a network during a same transmission time interval (TTI) of SRS interval; determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange; and entering into a sleep mode for the determined time duration till the next session of data exchange is initiated. The UE may include one or more hardware components in conjunction with the SPS alignment module 1108 such as a processor, memory, a transmitter, a receiver, a removable storage, and a non-removable storage, a bus and a network interface. The functionalities of these hardware components are not mentioned in detail as it is well known to a person skilled in the art.

The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Furthermore, the various devices, modules, and the like described herein may be enabled and operated using hardware circuitry, firmware, and/or software embodied in a machine readable medium. Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

METHOD AND SYSTEM FOR PROVIDING POWER OPTIMIZATION OF USER EQUIPMENTS IN CONNECTED MODE IN WIRELESS COMMUNICATION SYSTEMS

SAMSUNG R&D INSTITUTE INDIA – BANGALORE Pvt. Ltd.
# 2870, ORION Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanakundi Circle,
Marathahalli Post,
Bangalore -560037, Karnataka, India
Indian Company

The following Specification particularly describes the invention and the method it is being performed
FIELD OF THE INVNENTION
The present invention relates to wireless communication systems and more particularly to a system and method for power optimization of user equipment’s in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

BACKGROUND OF THE INVENTION
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems aims at providing higher data rates and lower latencies to the customers that can make wireless mobile devices a great platform to run a new whole set of services and applications. One of the key objectives to support this evolution is the improved efficiency of power utilization: LTE exploits the idea of Discontinuous Reception (DRX) and Discontinuous Transmission (DTX). The DRX cycle consists of an ‘On Duration’ during which the user equipment (UE) should monitor the Physical Downlink Control Channel (PDCCH) and a ‘DRX period’ during which a UE can skip reception of downlink channels for battery saving purposes. The DRX cycle specifies the periodic repetition of the ON duration followed by a possible period of inactivity.

In current system deployment, 3GPP has put substantial focus to minimize the power consumption in connected mode of operation of wireless communication system. As research efforts, multiple solution like connected mode DRX and Semi persistence solution has been proposed (36.321). Connected mode DRX is an elegant solution of reduce power consumption, which find the optimal trade off to wakes up the UE only at the time, when, there is some data is schedule. Connected mode DRX, when used, in conjunction with Semi persistence scheduling (SPS) provides further gain and avoid waking up UE, to read control channel for downlink (DL)/uplink (UL) resource allocation, since SPS pre-defines the assignment with SPS interval. However, unaligned nature of allocation/feedback can force UE to wake up and read the allocation or send feedback information. This would eat substantial gain achieved by the connected mode DRX design. Further, the main point of this functionality makes the terminal to not monitor the control channels continuously, but only in well-defined instants, turning the radiofrequency (RF) modem in a sleep state as much as possible. In fact, control data are low-frequency and low bit-rate, so continuous listening the related channels represents a big waste of power resource.

Therefore, there exists a need to provide a system and method for power optimization of user equipments in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent upon a reading of the specification and a study of the drawings.

SUMMARY OFTHE INVENTION
The various embodiments herein provide a method for optimizing power consumption of user equipment in wireless communication system. The method comprising steps of periodically exchanging control channel messages with a network during a same Transmission Time Interval (TTI) of Sounding Reference Signal (SRS) interval, wherein the control messages corresponds to Uplink (UL) and Downlink (DL) allocation and feedback messages, determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange and entering into a sleep mode for the determined time duration till the next session of data exchange is initiated.

According to an embodiment herein, TTI of the SRS interval corresponds to an active period of user equipment.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a SRS report to the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to a start of an ON duration time, receiving an UL grant message in Physical Downlink Control Channel (PDCCH) from the network after expiry of first transmission time interval (TTI), simultaneously sending a Channel Quality Indicator (CQI) report to the network at the same TTI in which the UL grant was received and entering into a sleep mode at a second TTI, wherein the UE is in a dynamic feedback mode.

According to an embodiment herein, the first transmission time interval corresponds to 4ms after the specific TTI and the second TTI corresponds to 8ms after the specific TTI.

According to an embodiment herein, receiving the UL grant message in PDCCH from the network after the expiry of first TTTI comprises of allocating uplink resources to the user equipment in PDCCH channel by the network and sending, by the network, the UL grant message in PDCCH to the UE based on SRS measurements.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a UL data in Physical Uplink Shared Channel (PUSCH) to the network on allocated resources after the expiry of the second TTI of the DRX cycle, simultaneously receiving a DL grant message and a DL data from the network at the same TTI in which the UL data was transmitted and entering a sleep mode at a third TTI.
According to an embodiment herein, the third TTI corresponds to 12ms after the specific TTI in which the SRS report was transmitted by the UE.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval in the active period of the user equipment comprises of processing the received DL data for a third TTI, transmitting a UL hybrid automatic repeat request (HARQ) feedback message to the network after the expiry of third TTI and simultaneously receiving DL HARQ feedback message in physical hybrid ARQ indicator channel (PHICH) from the network at the same TTI in which the UL HARQ feedback message was transmitted.

According to an embodiment herein, the method further comprises of re-transmitting, by the user equipment, the UL data when a negative acknowledgment (NACK) is received from the network and simultaneously receiving a retransmitted DL data upon sending a negative acknowledgment to the network.

According to an embodiment herein, entering into a sleep mode for the determined time duration till the next session of data exchange is initiated comprises of switching off radio frequency and baseband processor for optimal power optimization.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of receiving an UL grant message in PDCCH from the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to an ON duration time, transmitting a CQI/SRS report for next SPS data along with SPS UL data to the network after expiry of first transmission time interval (TTI), simultaneously receiving a SPS DL data from the network at the same TTI in which the UL data and CQI/SRS report was transmitted and entering into sleep mode for the second TTI, wherein the UE is in a semi static feedback mode.

According to an embodiment herein, retransmission of UL and DL data is not required when the UE is in semi static feedback mode.

According to an embodiment herein, the method further comprises of holding the transmission of CQI /SRS report to the network when the UE is in static feedback mode.

Embodiments herein further disclose a method for minimizing CQI report in wireless communication system, the method comprising the steps of periodically receiving a CQI report from a user equipment, determining whether a change in CQI value in the CQI report falls below a predefined threshold delta value of CQI at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SPS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the CQI falls below the predefined threshold delta value.

According to an embodiment herein, the first mode corresponds to dynamic feedback mode and the second mode corresponds to either semi static feedback mode or static feedback mode.

According to an embodiment herein, the method further comprises of determining whether change in ratio of acknowledgement (ACK) to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the first mode corresponds to a static feedback mode and the second mode is at least one of a semi static feedback mode or dynamic feedback reporting mode based on the TTI at which the change in ratio of ACK to NACK is measured.

According to an embodiment herein, the method further comprising computing CQI for wideband and sub bands, wherein the wideband has plurality of sub bands and deciding to communicate the CQI to the network if delta of CQI between subsequent wide bands is greater than threshold delta CQI and if delta of CQI between sub bands is not more than the threshold delta CQI.

Embodiments herein further disclose a method for minimizing SRS report in wireless communication system, the method comprising the steps of determining whether a change in UL signal to noise ratio (SINR) value in the SRS report falls below a predefined threshold delta value of UL SINR at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SRS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the UL SINR falls below the predefined threshold delta value of UL SINR.

According to an embodiment herein, the method further comprises of receiving SRS report from the UE in semi static feedback mode, determining whether change in ratio of ACK to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the method further comprises of defining hysteresis values for uplink and downlink signaling in order to protect the UE from the temporarily fluctuating channel and from the overhead of UL and DL signaling, comparing the values of change in CQI, change in UL SINR and change in ratio of ACK to NACK with the corresponding defined hysteresis values in the network and applying the corresponding reporting mode configuration on PDCCH in uplink and downlink based on the comparison.

According to an embodiment herein, further comprising monitoring ACK to NACK ratio to determine a change in a communication channel during a downlink data operation and periodically reporting CQI to the network when a change in the communication channel is determined.

According to an embodiment herein, the method further comprises of adapting to dynamic changes in the communication channel for a defined layer three configurations for SRS and CQI by providing protection at physical layer level and defining a two bit binary numbers for reporting mode configuration at the PUCCH for uplink and PDCCH for downlink, wherein each two bit binary numbers correspond to a specific reporting configuration mode.

According to an embodiment herein, the UE is actively monitoring downlink and is transmitting on the uplink.

According to an embodiment herein, switching off a transmission chain of the UE when the UE is actively monitoring DL and there are no uplink transmissions, wherein the UE is in light sleep mode.

According to an embodiment herein, the method further comprises of switching off both the transmission chain and receiving chain of the UE when the UE is not monitoring downlink and is transmitting on uplink, wherein radiofrequency (RF) and modem of the UE are in light sleep mode and switching off the RF and modem of the UE when the UE is not monitoring downlink or either transmitting in uplink, wherein the UE is in deep sleep mode.

According to an embodiment herein, the DL data comprises of a VoLTE data and timing advance medium access control (MAC) protocol data unit (PDU) and the UL data comprises of a VoLTE data and power head room reporting (PHR).

According to an embodiment herein, the method further comprises of aligning periodicity of timing alignment (TA) PDU and power head room reporting (PHR) PDU with uplink and downlink allocation as per SPS interval, wherein the periodicity of TA and PHR PDU are integer multiple of SPS interval.

Embodiments herein further disclose a user equipment, a wireless terminal and a non-transitory computer readable medium having a processor operable to perform the aforementioned method in collaboration.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a graphical representation of a Semi persistence scheduling (SPS) downlink packet drop probability in a single user scenario, according to an embodiment of the present invention.

Figure 2 is a schematic representation of data transfer operation of the UE where the UE is kept alive for long duration due to which there is an increase in the power consumption, according to a prior art.

Figure 3a is a timing diagram representing a common SPS transmission time interval (TTI) for UL and DL data, where the interval for SPS UL/DL and the interval for CQI/SRS is same, according to an embodiment of the present invention.

Figure 3b is a timing diagram representing a common SPS TTI for getting SPS UL/DL data and CQI/SRS, according to an embodiment of the present invention.

Figure 4a is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 4b is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL with HARQ retransmission, according to an embodiment of the present invention.

Figure 5 is a schematic representation of data transfer operation of the UE in semi static feedback reporting mode where CQI/SRS is having the same TTO as that of SPS UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 6 is a schematic representation of a wideband having N sub bands along with the computed CQI value, according to an embodiment of the present invention.

Figure 7 is a timing diagram for a reporting mode configuration in downlink, according to an embodiment of the present invention.

Figure 8 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for downlink, according to an embodiment of the present invention.

Figure 9 is a timing diagram of a reporting mode configuration in uplink, according to an embodiment of the present invention.

Figure 10 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for uplink, according to an embodiment of the present invention.

Figure 11 is a system diagram illustrating an exemplary wireless communication system, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others, this is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a system and method for power optimization of user equipment’s in connected mode in wireless communication systems. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

In a peer to peer conversation, there are there are several modes in which conversation can be classified as Discussion, Talking or Listening. One can always save power by switching uplink (UL)/downlink (DL) either or both ON or OFF, during various phases of conversation. In ‘talking’ mode of conversation, caller is continuously talking and peer entity is listening. Thus caller always need UL grants to send the data. In talking mode of operation, Caller should monitor PDCCH in downlink to receive UL allocation. The UE 1102 has to transmit sounding reference signal (SRS) for the purpose of enode B (eNB) 1104 UL channel state information (CSI) measurement. So that eNB 1104 can allocate the suitable UL resources to the UE 1102. However, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) medium access control (MAC) protocol data unit (PDU). This requires resources in the downlink on Physical Downlink Shared Channel (PDSCH). The UL acknowledgment/ negative acknowledgement (ACK/NACK) and CSI either send by Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH). The UE 1102 also keeps reporting PHR (power head room report) as the difference between MAX UE 1102 transmission (Tx) power and estimated Tx power on UL shared channel (SCH). This will also call for UL resources allocation.
Generally, all uplink channel (PUCCH, PUSCH, and SRS) and DL (PDCCH, PDSCH, and physical hybrid ARQ indicator channel (PHICH)) are in constant use during talking operation. In case of talking mode operation, to minimize the power, the present invention provides a method to align uplink and downlink course of operation.
In ‘listening’ mode of conversation, caller is continuously listening and peer entity is talking. Thus caller always need DL resources to receive the data. During listening mode of operation, UE 1102 needs to read PDCCH for the resource allocation on PDSCH. The UE 1102 also, have to measure the Reference signals in downlink and send CSI feedback in UL, in order to provide link adaptation and resource allocation in downlink and also, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) MAC PDU on PDSCH. This requires resources in the downlink on PDSCH. The UL ACK/NACK and CSI either send by PUSCH or PUCCH. UE 1102 also keep reporting PHR (power head room report) as the difference between MAX UE 1102 TX power and estimated Tx power on UL SCH. This will also call for UL resources allocation.
Generally, PUCCH, PUSCH and DL (PDCCH, PDSCH and PHICH) are in constant use during listening operation. In listening mode of operation, easy way to minimize the power is to align uplink and downlink course of operation and to minimize the periodicity of SRS transmission. A Caller can indicate the “listening” mode to network 1104 by using the toggle bit in PDCCH.
Figure 1 is a graphical representation of a SPS downlink packet drop probability in a single user scenario, according to an embodiment of the present invention. According to an embodiment of the present invention, SPS interval is considered to be 40ms for all the scenarios mentioned herein (voice CODEC generates the data every 20ms). Therefore, the UE 1102 and the enode B 1104 has to buffer the data until SPS interval and has to send the whole data as a single burst at the Semi persistence scheduling (SPS) transmission time interval (TTI). This saves UE 1102 power as UE 1102 can go to DRX for long time. For example, in case of large SPS (or DRX) intervals like 60ms and above, the delay is more and hence UE 1102 suffer from packet loss in DL, which is evident in Figure 1.

There can be four scenarios or modes in which UE 1102 goes to sleep and save power. In the first scenario which is in RRC connected mode (also referred as power state 1), the UE 1102 is actively monitoring DL and is also transmitting on the UL. In the second scenario which is also on RRC connected mode (also referred as power state 2), the UE 1102 is actively monitoring DL but there are no uplink transmissions (TX chain). Hence, the TX chain is turned off in this state. In the third scenario which is a light sleep mode (also referred as power state 3), the UE 1102 is not monitoring DL or transmitting on UL. Both the receive (Rx) and transmit (Tx) are turned off. The modem and RF are put in “light sleep mode”. In the last scenario which is a deep sleep mode (also referred as power state four), the UE 1102 is not monitoring DL or transmitting on UL. RF and modem are both shut down. The only modem power consumption is due to leakage.

Figure 2 is a schematic representation of data transfer operation of the

FORM 2
THE PATENTS ACT, 1970
[39 of 1970]
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; Rule 13)

METHOD AND SYSTEM FOR PROVIDING POWER OPTIMIZATION OF USER EQUIPMENTS IN CONNECTED MODE IN WIRELESS COMMUNICATION SYSTEMS

SAMSUNG R&D INSTITUTE INDIA – BANGALORE Pvt. Ltd.
# 2870, ORION Building, Bagmane Constellation Business Park,
Outer Ring Road, Doddanakundi Circle,
Marathahalli Post,
Bangalore -560037, Karnataka, India
Indian Company

The following Specification particularly describes the invention and the method it is being performed
FIELD OF THE INVNENTION
The present invention relates to wireless communication systems and more particularly to a system and method for power optimization of user equipment’s in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

BACKGROUND OF THE INVENTION
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems aims at providing higher data rates and lower latencies to the customers that can make wireless mobile devices a great platform to run a new whole set of services and applications. One of the key objectives to support this evolution is the improved efficiency of power utilization: LTE exploits the idea of Discontinuous Reception (DRX) and Discontinuous Transmission (DTX). The DRX cycle consists of an ‘On Duration’ during which the user equipment (UE) should monitor the Physical Downlink Control Channel (PDCCH) and a ‘DRX period’ during which a UE can skip reception of downlink channels for battery saving purposes. The DRX cycle specifies the periodic repetition of the ON duration followed by a possible period of inactivity.

In current system deployment, 3GPP has put substantial focus to minimize the power consumption in connected mode of operation of wireless communication system. As research efforts, multiple solution like connected mode DRX and Semi persistence solution has been proposed (36.321). Connected mode DRX is an elegant solution of reduce power consumption, which find the optimal trade off to wakes up the UE only at the time, when, there is some data is schedule. Connected mode DRX, when used, in conjunction with Semi persistence scheduling (SPS) provides further gain and avoid waking up UE, to read control channel for downlink (DL)/uplink (UL) resource allocation, since SPS pre-defines the assignment with SPS interval. However, unaligned nature of allocation/feedback can force UE to wake up and read the allocation or send feedback information. This would eat substantial gain achieved by the connected mode DRX design. Further, the main point of this functionality makes the terminal to not monitor the control channels continuously, but only in well-defined instants, turning the radiofrequency (RF) modem in a sleep state as much as possible. In fact, control data are low-frequency and low bit-rate, so continuous listening the related channels represents a big waste of power resource.

Therefore, there exists a need to provide a system and method for power optimization of user equipments in connected mode in wireless communication systems by aligning uplink and downlink grants, data and control channel.

The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent upon a reading of the specification and a study of the drawings.

SUMMARY OFTHE INVENTION
The various embodiments herein provide a method for optimizing power consumption of user equipment in wireless communication system. The method comprising steps of periodically exchanging control channel messages with a network during a same Transmission Time Interval (TTI) of Sounding Reference Signal (SRS) interval, wherein the control messages corresponds to Uplink (UL) and Downlink (DL) allocation and feedback messages, determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange and entering into a sleep mode for the determined time duration till the next session of data exchange is initiated.

According to an embodiment herein, TTI of the SRS interval corresponds to an active period of user equipment.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a SRS report to the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to a start of an ON duration time, receiving an UL grant message in Physical Downlink Control Channel (PDCCH) from the network after expiry of first transmission time interval (TTI), simultaneously sending a Channel Quality Indicator (CQI) report to the network at the same TTI in which the UL grant was received and entering into a sleep mode at a second TTI, wherein the UE is in a dynamic feedback mode.

According to an embodiment herein, the first transmission time interval corresponds to 4ms after the specific TTI and the second TTI corresponds to 8ms after the specific TTI.

According to an embodiment herein, receiving the UL grant message in PDCCH from the network after the expiry of first TTTI comprises of allocating uplink resources to the user equipment in PDCCH channel by the network and sending, by the network, the UL grant message in PDCCH to the UE based on SRS measurements.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of transmitting a UL data in Physical Uplink Shared Channel (PUSCH) to the network on allocated resources after the expiry of the second TTI of the DRX cycle, simultaneously receiving a DL grant message and a DL data from the network at the same TTI in which the UL data was transmitted and entering a sleep mode at a third TTI.
According to an embodiment herein, the third TTI corresponds to 12ms after the specific TTI in which the SRS report was transmitted by the UE.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval in the active period of the user equipment comprises of processing the received DL data for a third TTI, transmitting a UL hybrid automatic repeat request (HARQ) feedback message to the network after the expiry of third TTI and simultaneously receiving DL HARQ feedback message in physical hybrid ARQ indicator channel (PHICH) from the network at the same TTI in which the UL HARQ feedback message was transmitted.

According to an embodiment herein, the method further comprises of re-transmitting, by the user equipment, the UL data when a negative acknowledgment (NACK) is received from the network and simultaneously receiving a retransmitted DL data upon sending a negative acknowledgment to the network.

According to an embodiment herein, entering into a sleep mode for the determined time duration till the next session of data exchange is initiated comprises of switching off radio frequency and baseband processor for optimal power optimization.

According to an embodiment herein, periodically exchanging the control channel messages with the network during the same transmission time interval (TTI) of the SRS interval comprises of receiving an UL grant message in PDCCH from the network at a specific TTI of a DRX cycle, wherein the specific TTI corresponds to an ON duration time, transmitting a CQI/SRS report for next SPS data along with SPS UL data to the network after expiry of first transmission time interval (TTI), simultaneously receiving a SPS DL data from the network at the same TTI in which the UL data and CQI/SRS report was transmitted and entering into sleep mode for the second TTI, wherein the UE is in a semi static feedback mode.

According to an embodiment herein, retransmission of UL and DL data is not required when the UE is in semi static feedback mode.

According to an embodiment herein, the method further comprises of holding the transmission of CQI /SRS report to the network when the UE is in static feedback mode.

Embodiments herein further disclose a method for minimizing CQI report in wireless communication system, the method comprising the steps of periodically receiving a CQI report from a user equipment, determining whether a change in CQI value in the CQI report falls below a predefined threshold delta value of CQI at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SPS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the CQI falls below the predefined threshold delta value.

According to an embodiment herein, the first mode corresponds to dynamic feedback mode and the second mode corresponds to either semi static feedback mode or static feedback mode.

According to an embodiment herein, the method further comprises of determining whether change in ratio of acknowledgement (ACK) to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the first mode corresponds to a static feedback mode and the second mode is at least one of a semi static feedback mode or dynamic feedback reporting mode based on the TTI at which the change in ratio of ACK to NACK is measured.

According to an embodiment herein, the method further comprising computing CQI for wideband and sub bands, wherein the wideband has plurality of sub bands and deciding to communicate the CQI to the network if delta of CQI between subsequent wide bands is greater than threshold delta CQI and if delta of CQI between sub bands is not more than the threshold delta CQI.

Embodiments herein further disclose a method for minimizing SRS report in wireless communication system, the method comprising the steps of determining whether a change in UL signal to noise ratio (SINR) value in the SRS report falls below a predefined threshold delta value of UL SINR at consecutive TTIs, wherein the consecutive TTIs corresponds to integer multiple of SRS interval and triggering the user equipment to switch from a first mode to a second mode via a PDCCH if the change in the UL SINR falls below the predefined threshold delta value of UL SINR.

According to an embodiment herein, the method further comprises of receiving SRS report from the UE in semi static feedback mode, determining whether change in ratio of ACK to NACK is greater than a predefined threshold delta value of the ratio of ACK to NACK at a particular TTI, triggering the user equipment to switch from a first mode to a second mode via a PDCCH by the network if the ratio of ACK to NACK falls below the predefined threshold delta value of the ratio of ACK to NACK and restoring periodicity of CQI.

According to an embodiment herein, the method further comprises of defining hysteresis values for uplink and downlink signaling in order to protect the UE from the temporarily fluctuating channel and from the overhead of UL and DL signaling, comparing the values of change in CQI, change in UL SINR and change in ratio of ACK to NACK with the corresponding defined hysteresis values in the network and applying the corresponding reporting mode configuration on PDCCH in uplink and downlink based on the comparison.

According to an embodiment herein, further comprising monitoring ACK to NACK ratio to determine a change in a communication channel during a downlink data operation and periodically reporting CQI to the network when a change in the communication channel is determined.

According to an embodiment herein, the method further comprises of adapting to dynamic changes in the communication channel for a defined layer three configurations for SRS and CQI by providing protection at physical layer level and defining a two bit binary numbers for reporting mode configuration at the PUCCH for uplink and PDCCH for downlink, wherein each two bit binary numbers correspond to a specific reporting configuration mode.

According to an embodiment herein, the UE is actively monitoring downlink and is transmitting on the uplink.

According to an embodiment herein, switching off a transmission chain of the UE when the UE is actively monitoring DL and there are no uplink transmissions, wherein the UE is in light sleep mode.

According to an embodiment herein, the method further comprises of switching off both the transmission chain and receiving chain of the UE when the UE is not monitoring downlink and is transmitting on uplink, wherein radiofrequency (RF) and modem of the UE are in light sleep mode and switching off the RF and modem of the UE when the UE is not monitoring downlink or either transmitting in uplink, wherein the UE is in deep sleep mode.

According to an embodiment herein, the DL data comprises of a VoLTE data and timing advance medium access control (MAC) protocol data unit (PDU) and the UL data comprises of a VoLTE data and power head room reporting (PHR).

According to an embodiment herein, the method further comprises of aligning periodicity of timing alignment (TA) PDU and power head room reporting (PHR) PDU with uplink and downlink allocation as per SPS interval, wherein the periodicity of TA and PHR PDU are integer multiple of SPS interval.

Embodiments herein further disclose a user equipment, a wireless terminal and a non-transitory computer readable medium having a processor operable to perform the aforementioned method in collaboration.

The foregoing has outlined, in general, the various aspects of the invention and is to serve as an aid to better understanding the more complete detailed description which is to follow. In reference to such, there is to be a clear understanding that the present invention is not limited to the method or application of use described and illustrated herein. It is intended that any other advantages and objects of the present invention that become apparent or obvious from the detailed description or illustrations contained herein are within the scope of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

Figure 1 is a graphical representation of a Semi persistence scheduling (SPS) downlink packet drop probability in a single user scenario, according to an embodiment of the present invention.

Figure 2 is a schematic representation of data transfer operation of the UE where the UE is kept alive for long duration due to which there is an increase in the power consumption, according to a prior art.

Figure 3a is a timing diagram representing a common SPS transmission time interval (TTI) for UL and DL data, where the interval for SPS UL/DL and the interval for CQI/SRS is same, according to an embodiment of the present invention.

Figure 3b is a timing diagram representing a common SPS TTI for getting SPS UL/DL data and CQI/SRS, according to an embodiment of the present invention.

Figure 4a is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 4b is a schematic representation of data transfer operation of the UE in dynamic feedback reporting mode having same SPS TTI for UL and DL with HARQ retransmission, according to an embodiment of the present invention.

Figure 5 is a schematic representation of data transfer operation of the UE in semi static feedback reporting mode where CQI/SRS is having the same TTO as that of SPS UL and DL without HARQ retransmission, according to an embodiment of the present invention.

Figure 6 is a schematic representation of a wideband having N sub bands along with the computed CQI value, according to an embodiment of the present invention.

Figure 7 is a timing diagram for a reporting mode configuration in downlink, according to an embodiment of the present invention.

Figure 8 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for downlink, according to an embodiment of the present invention.

Figure 9 is a timing diagram of a reporting mode configuration in uplink, according to an embodiment of the present invention.

Figure 10 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for uplink, according to an embodiment of the present invention.

Figure 11 is a system diagram illustrating an exemplary wireless communication system, according to an embodiment of the present invention.

Although specific features of the present invention are shown in some drawings and not in others, this is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a system and method for power optimization of user equipment’s in connected mode in wireless communication systems. In the following detailed description of the embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims.

In a peer to peer conversation, there are there are several modes in which conversation can be classified as Discussion, Talking or Listening. One can always save power by switching uplink (UL)/downlink (DL) either or both ON or OFF, during various phases of conversation. In ‘talking’ mode of conversation, caller is continuously talking and peer entity is listening. Thus caller always need UL grants to send the data. In talking mode of operation, Caller should monitor PDCCH in downlink to receive UL allocation. The UE 1102 has to transmit sounding reference signal (SRS) for the purpose of enode B (eNB) 1104 UL channel state information (CSI) measurement. So that eNB 1104 can allocate the suitable UL resources to the UE 1102. However, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) medium access control (MAC) protocol data unit (PDU). This requires resources in the downlink on Physical Downlink Shared Channel (PDSCH). The UL acknowledgment/ negative acknowledgement (ACK/NACK) and CSI either send by Physical Uplink Shared Channel (PUSCH) or Physical Uplink Control Channel (PUCCH). The UE 1102 also keeps reporting PHR (power head room report) as the difference between MAX UE 1102 transmission (Tx) power and estimated Tx power on UL shared channel (SCH). This will also call for UL resources allocation.
Generally, all uplink channel (PUCCH, PUSCH, and SRS) and DL (PDCCH, PDSCH, and physical hybrid ARQ indicator channel (PHICH)) are in constant use during talking operation. In case of talking mode operation, to minimize the power, the present invention provides a method to align uplink and downlink course of operation.
In ‘listening’ mode of conversation, caller is continuously listening and peer entity is talking. Thus caller always need DL resources to receive the data. During listening mode of operation, UE 1102 needs to read PDCCH for the resource allocation on PDSCH. The UE 1102 also, have to measure the Reference signals in downlink and send CSI feedback in UL, in order to provide link adaptation and resource allocation in downlink and also, to keep the UE 1102 always in DL sync, eNB 1104 also have to transmit Timing advance (TA) MAC PDU on PDSCH. This requires resources in the downlink on PDSCH. The UL ACK/NACK and CSI either send by PUSCH or PUCCH. UE 1102 also keep reporting PHR (power head room report) as the difference between MAX UE 1102 TX power and estimated Tx power on UL SCH. This will also call for UL resources allocation.
Generally, PUCCH, PUSCH and DL (PDCCH, PDSCH and PHICH) are in constant use during listening operation. In listening mode of operation, easy way to minimize the power is to align uplink and downlink course of operation and to minimize the periodicity of SRS transmission. A Caller can indicate the “listening” mode to network 1104 by using the toggle bit in PDCCH.
Figure 1 is a graphical representation of a SPS downlink packet drop probability in a single user scenario, according to an embodiment of the present invention. According to an embodiment of the present invention, SPS interval is considered to be 40ms for all the scenarios mentioned herein (voice CODEC generates the data every 20ms). Therefore, the UE 1102 and the enode B 1104 has to buffer the data until SPS interval and has to send the whole data as a single burst at the Semi persistence scheduling (SPS) transmission time interval (TTI). This saves UE 1102 power as UE 1102 can go to DRX for long time. For example, in case of large SPS (or DRX) intervals like 60ms and above, the delay is more and hence UE 1102 suffer from packet loss in DL, which is evident in Figure 1.

There can be four scenarios or modes in which UE 1102 goes to sleep and save power. In the first scenario which is in RRC connected mode (also referred as power state 1), the UE 1102 is actively monitoring DL and is also transmitting on the UL. In the second scenario which is also on RRC connected mode (also referred as power state 2), the UE 1102 is actively monitoring DL but there are no uplink transmissions (TX chain). Hence, the TX chain is turned off in this state. In the third scenario which is a light sleep mode (also referred as power state 3), the UE 1102 is not monitoring DL or transmitting on UL. Both the receive (Rx) and transmit (Tx) are turned off. The modem and RF are put in “light sleep mode”. In the last scenario which is a deep sleep mode (also referred as power state four), the UE 1102 is not monitoring DL or transmitting on UL. RF and modem are both shut down. The only modem power consumption is due to leakage.

Figure 2 is a schematic representation of data transfer operation of the UE 1102 where the UE 1102 is kept alive for long duration due to which there is an increase in the power consumption, according to a prior art. One of the major problems for more power consumption in UE 1102 can be the dis-aligned pattern of resource allocation for UL and DL, also dis-aligned reporting of channel quality indicator (CQI) and SRS. Thus it can be overcome by some mechanism which can align the resource allocation and CQI/SRS reporting. Figure 2 shows how the UE 1102 will keep alive for long duration due to which power consumption will increase. It shows that UE 1102 is consuming power for more than half of DRX cycle in worst case scenario. Thus to overcome this problem, the present invention provides a method to align the resource allocation and CQI/SRS reporting. This would provide sufficient time for UE 1102 for micro sleep.

Figure 3a is a timing diagram representing a common SPS TTI for UL and DL data, where the interval for SPS UL/DL and the interval for CQI/SRS is same, according to an embodiment of the present invention. According to an embodiment of the present invention, power consumption can be reduced if the SPS configuration for data Transmission in UL and DL interval is same and align in the same TTI. The UE 1102 can wake up only at that SPS intervals and can go to light sleep mode for remaining period of time as connected mode DRX. This saves the UE 1102 power largely. If the CQI and SRS reporting are also configured at the same periodicity of the SPS interval, then the UE 1102 can send CQI/SRS in active time and UE 1102 does not have to wake up separately in other TTI’s to report CQI and SRS. Figure 3a shows that the SPS TTI for UL and DL is same, the interval for the SPS UL/DL and the interval for the CQI/SRS is same.

Figure 3b is a timing diagram representing a common SPS TTI for getting SPS UL/DL data and CQI/SRS, according to an embodiment of the present invention. Figure 3b shows that the TTI to get SPS UL/DL data and CQI/SRS report is same, i.e., both the SPS UL/DL data transmission and CQI/SRS reporting occurs in active time, but that may or may not be same TTI. So, the UE 1102 need not wake up separately for the reporting and data transmission. This saves UE 1102 power by shutting down the baseband and RF processor. Based on the UE 1102 capability, UE 1102 can opt to go in light sleep for either UL/DL or both UE 1102.

According to an embodiment of the present invention, if the SPS TTI for UL and DL are same, then the UE 1102 can wake-up for 1 TTI to get DL and UL resource allocation and ACK/NACK through PDCCH and PUCCH. Further, the UE 1102 has to piggy back the CQI/SRS as it cannot be reported along with ACK/NACK.

In SPS based operation, since the TTI in which UE 1102 receives grant is already known, the UE 1102 does not have to monitor PDCCH, neither in on duration timer or inactivity timer. So, for VOLTE operation ON duration timer can be reduced to 1 TTI and inactivity timer can be removed. In case of successful transmission of UL data, ACK is received. However in case of re-transmission, UL data can be sent in next immediate TTI in which NACK has to be received.

As a normal course of operation, the UE 1102 decodes DL data in the same TTI, in which it gets PDCCH grant. However for uplink, UE 1102 receives grant in nth TTI for the transmission on PUSCH on n+4 (TTI). For both DL and UL operation, ACK, NACK comes after 4ms, which is a processing time. UE 1102 /eNB 1104 takes another 4ms for the Re-transmission or the transmission of new packet.

In order to allocate resources on UL or DL, the UE 1102 should measure the CSI in downlink and send CQI after n+4 TTI on PUCCH. Similarly, for UL, SRS should be transmitted by UE 1102 to get resources for uplink with the configured periodicity. Since it’s a SPS based scheduling, UE 1102 does not have to send SR on PUCCH. Moreover, to keep the UE 1102 in UL sync, eNB 1104 has to keep sending MAC PDU in downlink and Power headroom reporting should be done in uplink, which requires more PUSCH resources.

In an embodiment of the present invention, the UE 1102 sends CQI report and SRS signal within the active time without waking up separately. So, the UE 1102 is active for very less time within DRX cycle, which saves the UE 1102 power largely. When there is no data in UL and DL, UE 1102 makes the RF switch off (light sleep), which saves the UE 1102 power.

According to an embodiment of the present invention, SPS downlink data in PDSCH consists of the VOLTE data and the timing advanced MAC PDU. However, SPS uplink data in PUSCH consists of volte data and power head room reporting.

In the present invention, periodicity of Timing alignment PDU and power head room reporting PDU are aligned with UL and DL allocation as per SPS interval i.e. Periodicity of TA and PHR PDU should be in integer multiple of SPS interval.

The present invention defines three modes of operation for the UE 1102 based on the channel, namely, dynamic feedback reporting mode, semi static feedback reporting mode and static feedback reporting mode.

Figure 4a is a schematic representation of data transfer operation of the UE 1102 in dynamic feedback reporting mode having same SPS TTI for UL and DL without HARQ retransmission, according to an embodiment of the present invention. According to Figure 4, a SRS report is sent from UE 1102 at the ‘N’th TTI of the DRX cycle, which is start of the on duration time. The UL grant comes after 4ms, which is N+4 TTI. In order to optimize the UL transmission, UE 1102 sends the CQI report at the N+4 TTI. In this embodiment, it is assumed that the UE 1102 measures the SINR for 4 TTI’s and derives CQI which is sent in the N+4 TTI.

FN * DRX_CYCLE (4) +1 => SRS
FN * DRX_CYCLE (4) +5 => SPS UL grant / CQI report
FN * DRX_CYCLE (4) +9 => SPS DL data / SPS UL data
FN * DRX_CYCLE (4) +13 => DL / UL HARQ ACK/NACK
FN * DRX_CYCLE (4) +17 => SPS DL / UL Data Re RX / TX
FN * DRX_CYCLE (4) +21 => DL / UL HARQ ACK for Re TX / RX

In an embodiment of the present invention, the ENodeB 1104 measures the channel on sounding reference signals i.e., SRS and allocates the UL resources to UE 1102 by PDDCH. The ENodeB 1104 sends UL grant in PDCCH in N+4 TTI based on the SRS measurements and the UE 1102 sends the UL transmit data on the allocated resources in N+8 TTI. After receiving the grant on PDCCH, the UE 1102 takes 4ms of processing time before sending the UL data on PUSCH.

After CQI report has been sent from UE 1102 in PUSCH, the eNodeB 1104 takes 4ms to send the DL grant in PDCCH and DL data in PDSCH. So, at the N+8 TTI, the UE 1102 transmits UL data in PUSCH and also receives the DL grant (and DL data) in PDCCH (in PDSCH). After receiving the DL data in PDSCH, the UE 1102 takes 4ms to process and send UL HARQ feedback. At the same time, eNodeB 1104 will also take 4ms to process the received data and sends the DL HARQ feedback in the PHICH. So, as per the present invention, at N+12 TTI, UE 1102 sends UL HARQ feedback and also receives the DL HARQ feedback.

Figure 4b is a schematic representation of data transfer operation of the UE 1102 in dynamic feedback reporting mode having same SPS TTI for UL and DL with HARQ retransmission, according to an embodiment of the present invention. In case of re-transmission, the UE 1102 re-transmits UL data at N+16 TTI. However, the eNodeB 1104 can also re-send DL data at N+16 TTI. The UE 1102 takes 4 TTI to process the DL data and send the UL HARQ ACK at N+20 TTI. Similarly, the eNodeB 1104 also processes the UL data and sends the DL HARQ ACK at N+20 TTI. Hence, the TX and RX operation is aligned in such a way, so that the UE 1102 can utilize the maximum time of DRX operation in sleep and consequently the UE 1102 can shut down the RF and baseband processor for optimal power optimization.

Figure 5 is a schematic representation of data transfer operation of the UE 1102 in semi static feedback reporting mode where CQI/SRS is having the same TTO as that of SPS UL and DL without HARQ retransmission, according to an embodiment of the present invention. When channel is considered to be largely static then periodicity of UE 1102 feedback can be minimized and reported UE 1102 feedback can be used for the SPS after DRX cycle. It can be identified by examining the toggle bit in PUCCH. In order to reduce the UE 1102 wake-up time, the CQI/SRS interval and UL/DL SPS interval are aligned within the same TTI in active time. In this scenario, CQI report, SRS, UL data transmission and reception of DL data happens in same TTI. So, the UE 1102 goes to light sleep until DL HARQ feedback comes on PHICH and UL HARQ feedback is ready to be sent in PUCCH. As shown in the Figure 5, in Nth TTI of DRX cycle the UE 1102 receives the SPS UL grant and starts preparing the UL data. The UL and DL grants are sent by the network 1104 depending upon CQI/SRS report received in previous DRX cycle. The UE 1102 starts measuring the SINR to report CQI at N+4 TTI. The UE 1102 sends UL data and receives DL data in same TTI, which is N+ 4 TTI of DRX cycles, which is also SPS TTI, configured for UL and DL data.

If UE 1102 schedules the CQI and SRS reporting in the same TTI, then the UE 1102 can sleep in other TTI’s, which saves UE 1102 power more. Here, the CQI/SRS report sent is used for resource allocation of UL and DL for the next SPS interval. So, the active time in DRX cycle is less and the UE 1102 wakeup time is only 2TTI’s in active time and the remaining TTI’s UE 1102 goes to light sleep.

In static feedback reporting mode, where user is either stationary or with very limited mobility, the channel is assumed to be largely stationary and CQI/SRS measurements are least expected to be change. This can be leveraged in the power optimization of VOLTE design. The UE 1102 can minimize or avoid the transmission of CQI/SRS (under, periodicity, which is, configured by L3 signaling) and hence can save the power, which is required to report CQI and in sending SRS to measure UL channel state information. The table below depicts the relation between CQI and modulation:

CQI 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Modulation QPSK QPSK QPSK QPSK QPSK QPSK 16QAM 16Q
AM 16QAM 64QAM 64QAM 64QAM 64QAM 64QAM 64QAM
MCS 0 0 2 5 7 9 12 14 16 20 23 25 27 28 28

Figure 6 is a schematic representation of a wideband having N sub bands along with the computed CQI value, according to an embodiment of the present invention. By observing the pattern of computed CQI value, the UE 1102 can decide on communicating the CQI to eNodeB 1104. The UE 1102 has to check the CQI variation between subsequent sub-bands and also CQI variation across transmission TTI as per periodicity configured by layer-3. In Figure 6, where the wide band has ‘N’ sub bands (in this fig, wide band have 4 sub bands), the UE 1102 computes the CQI for wide band as CQI(?WB?_t) and also computes CQI for subbands of this wide band. The UE 1102 then decides to communicate the CQI to eNodeB 1104, only if the delta of CQI between subsequent wide bands is greater that threshold delta ‘?CQI?_D’, along with this the UE 1102 also checks that the delta of CQI between sub bands should not be more than threshold delta? CQI?_d.

Thus, UE 1102 communicates CQI if and only of,
CQI(?WB?_(t+1) )-CQI(?WB?_t )>?CQI?_(D ) 1
CQI(?SB?_(t+1)^i )-CQI(?SB?_t^i )>?CQI?_d 2
? t where in t=1 to N_TTI And i is the ith subband in bandwith

The UE 1102 keeps measuring and keeps reporting CQI during the connected mode of operation consequently network 1104 and allocates MCS.

Figure 7 is a timing diagram for a reporting mode configuration in downlink, according to an embodiment of the present invention. According to Figure 7, the UE 1102 measures the SINR on the wideband /Sub band RS and sends the measured wideband /Sub band CQI report to eNB 1104 as per figure 4a and 4b. The enodeB (eNB) 1104 then monitors the CQI variation for consecutive N_TTI. In case, if change in CQI, falls below CQI_d then the eNb 1104 triggers to change the reporting mode configuration to “semi static feedback mode: 01” via PDCCH. After receiving the reporting mode configuration, the UE 1102 sends the CQI report (as per figure 5) regardless of configured CQI periodicity in layer 3 message. The eNb 1104 will further monitor the CQI variation for consecutive M x N_TTI. In case, if change in CQI falls below CQI_d, then the eNb 1104 sends trigger to change the reporting mode configuration to “static feedback mode: 10”, wherein M is defined as number of cycles for N_TTI. After changing reporting mode from “Dynamic feedback mode” to any other feedback mode, the eNb 1104 starts monitoring ACK/NACK ratio at the eNB 1104 for UE 1102. As long as, change in ratio of ACK/NACK remains less than ?Ratio_(ack/nack_DL )wherein, ??Ratio?_(ack/nack_DL )is measured for? N?_TTI. , the eNb 1104 allocates SPS and feedback allocation according to figure 4a/4b or figure 5. As soon as, change in ratio of ACK/NACK becomes greater than (or equal to) ?Ratio_(ack/nack_DL ), then eNB 1104 informs UE 1102 via PDCCH to change the reporting mode to “semi static feedback mode : 01” by below given protocol structure. The change in ratio of ACK/NACK is observed incrementally for N_(MeasInterval_dl)^ . If ACK/NACK ratio is found to be changing greater than ?Ratio_(ack/nack_DL ) then, the reporting mode is changed to dynamic reporting and periodicity of CQI is restored as configured by Layer3 configuration.

Thus, the CQI reporting is minimized which is useful in stationary UE 1102’s. (If CQI is not received from UE 1102 before 4 TTI’s from SPS DL interval, the network 1104 decides that CQI is not changed and will allocate the previous resources for DL data).

Figure 8 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for downlink, according to an embodiment of the present invention. At step 802, SPS UL/DL grant, CQI, SRS, DL/UL HARQ, ACK/NACK is aligned in a dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel. At step 804, change in CQI is measured for N_TTI. At step 806, it is determined whether the change in CQI falls below ?CQI?_d and hysteresis for ?CQI?_(d_hys). If yes, then at step 808, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned (as per figure 5), in a semi static feedback reporting mode. The enode B 1104 changes configuration mode by PDCCH or downlink common control channel. If the change in CQI does not fall below ?CQI?_d and hysteresis for ?CQI?_(d_hys), then the process is transferred to step 804. At step 810, change in CQI is measured for M x N_TTI. At step 812, it is checked whether the change in CQI falls below ?CQI?_d and hysteresis for ?CQI?_(d_hys). If so, then at step 814, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned in a static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. On the other hand, if the change in CQI does not fall below ?CQI?_d and hysteresis for ?CQI?_(d_hys), then the process is transferred to step 810. At step 816, the ACK/NACK ratio is constantly measured by eNB 1104. At step 818, it is determined whether a change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_DL) and hysteresis for ??Ratio?_(ack/nack_DL_hys). If yes, then the process is transferred to step 816. If not, then at step 820, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned in a semi static feedback reporting mode. The enB 1104 changes configuraiton mode by PDCCH or downlink common control channel. At step 822, changes in ACK/NACK ratio are measured for N_(MeasInterval_dl). At step 824, it checked whether change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_DL) and hysteresis for ??Ratio?_(ack/nack_DL_hys). If yes, then the process is transferred back to step 816. If no, then at step 826, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned back in dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel.

Figure 9 is a timing diagram of a reporting mode configuration in uplink, according to an embodiment of the present invention. According to Figure 9, the eNB 1104 measures the UL SINR on SRS and allocates UL physical resource allocation for the purpose of channel adaptation in UL. The eNB 1104 monitors the UL SINR on SRS for consecutive N_TTI. In case, if change in UL SINR falls below ?UL_?SINR?_d then eNb 1104 triggers to change the reporting mode configuration to “semi static feedback mode: 01” via PDCCH. The eNB 1104 further monitors the UL SINR variation for consecutive M x N_TTI. If change in UL SINR falls below ?UL_?SINR?_d then, the eNB 1104 triggers to change the reporting mode configuration to “static feedback mode: 10” wherein, M is defined as number of N_TTI cycles. Otherwise, the eNB 1104 keeps operating in the configured operating mode. The SRS is transmitted by the UE 1102 as defined in Fig 4.a /4.b and Fig-5 respectively for “semi static feedback” reporting. After changing reporting mode from – “Dynamic feedback mode” to any other feedback mode, the eNB 1104 monitors ACK/NACK ratio at the eNB 1104 for UE 1102. As long as, change in ratio of ACK/NACK remains less than ??Ratio?_(ack/nack_uL )wherein, ??Ratio?_(ack/nack_uL )is measured for N_TTI, the eNB 1104 allocates the UL SPS allocation and feedback allocation according to fig 4a/4b or fig -5. As soon as, change in ratio of ACK/NACK becomes greater then (or equal to) ??Ratio?_(ack/nack_uL ), then eNb 1104 informs to UE 1102 via PDCCH to change the reporting mode to “semi static feedback mode : 01” by below given protocol structure. The change in ratio of ACK/NACK is observed incrementally for N_(MeasInterval_dl)^ . If ACK/NACK ratio is found to be changing and is greater than ??Ratio?_(ack/nack_uL ) then, the reporting mode is changed to dynamic reporting and periodicity of CQI is restored as configured by Layer3 configuration.

According to an embodiment of the present invention, if ??Ratio?_(ack/nack_UL ), ??Ratio?_(ack/nack_DL ) , ?CQI?_d,?UL_?SINR?_d are left unbound then, the UE 1102 might suffer from the overhead of UL and DL signaling, especially where channel is fluctuating temporarily. This would consume all the gains, which were accrued by virtue of proposed UL ad DL control singling to reduce the UL control transmission. In order to protect the temporarily fluctuation an additional Hysteresis say ??Ratio?_(ack/nack_UL_hys ) and ??Ratio?_(ack/nack_DL_hys ), ?CQI?_(d_hys),?UL_?SINR?_(d_hys) could be added, which does not allow to trigger the UL and DL control channel signaling with instantaneous channel changes. As in implementation,

For Uplink,
??Ratio?_(ack/nack_UL ) in Uplink and ACK /NACK ratio becomes greater than ??Ratio?_(ack/nack_DL ) in downlink then, the reporting mode configuration is applied on PDCCH only, if change in UL_SINR measured is greater than ?UL_?SINR?_(d_hys) for consecutive ?NTTI?_(ul_Hys) . Further, the reporting mode configuration is also applied on PDCCH only, if ACK/NACK ratio is measured greater than ??Ratio?_(ack/nack_UL_hys )for consecutive ?NTTI?_(ul_Hys) .

For downlink, the reporting mode configuration is applied on PDCCH only if change in CQI measured is greater than ?CQI?_(d_hys)for consecutive ?NTTI?_(Dl_Hys) . Further, the reporting mode configuration is applied on PDCCH only if ACK/NACK ratio is measured greater than ??Ratio?_(ack/nack_DL_hys )for consecutive ?NTTI?_(Dl_Hys) .

In case of DL data operation, the CQI reporting mode, as in current ART is configured by the higher layer and is not expected to be changed per TTI or per “X” TTI where in X>1 . As per present invention, the UE 1102 is expected to report the CQI even though channel is static or quasi static, where in, change in channel, has very minimum impact on BLER and in worst case, the same is protected by HARQ at the cost of re-transmissions.

In case of UL data operation, the SRS is transmitted as per the configured periodicity by Layer-3 configuration as in current ART. However, the disadvantage is that, it fails to handle the dynamic changes in the channel, which can add significant value, especially where fix allocation and periodic grants are required. The present invention provides additional protection at physical layer level to combat with the dynamic changes in the channel for a given layer 3 configurations for SRS and CQI. The reporting mode can be configured by 2 bit at the PUCCH for UL and PDCCH for DL, wherein 4 configuration modes are possible.

UL/DL configuration mode
0: Uplink
1: Downlink
00 – Dynamic feedback reporting mode
01 – Semi static feedback reporting mode.
10 – Static feedback reporting mode.
11- Reserved.

For a given periodicity, as configured by the RRC signaling, the UE 1102 is configured in below given mode by PDCCH.

Figure 10 is a process flowchart depicting the process of minimizing CQI/SRS report and aligning the UL/DL grants and HARQ ACK NACK for uplink, according to an embodiment of the present invention. at step 1002, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 4.a and 4.b in a dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel. At step 1004, change in ??UL_SINR?_d for N_TTI is measured. At step 1006, it is checked whether change in UL_SINR falls below ??UL_SINR?_d and hysteresis for ??UL_SINR?_(d_hys). If no, then the process is transferred back to step 1004. If yes, then at step 1008, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned (as per figure 5), in a semi static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1010, change in UL_SINR for M x? N?_TTI is measured. At step 1012, it is checked whether change in UL_SINR falls below ??UL_SINR?_d and hysteresis for ??UL_SINR?_(d_hys). If no, then the process is transferred back to step 1010. If yes, then at step 1014, SPS UL/DL grant CQI SRS, DL/UL HARQ ACK/NACK are aligned as per figure 6, in a static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1016, the ACk/NACK ratio is constantly measured by the eNB 1104. At step 1018, it is checked whether the change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_uL ) and hysteresis for ??Ratio?_(ack/nack_UL_hys ). If yes, then the process is transferred back to step 1016. If no, then at step 1020, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 5, in a semi static feedback reporting mode. The enB 1104 changes configuration mode by PDCCH or downlink common control channel. At step 1022, changes in ACK/NACK ratio are measured for N_(MeasInterval_dl). At step 1024, it is checked whether change in ACK/NACK ratio falls below ??Ratio?_(ack/nack_uL ) and hysteresis for ??Ratio?_(ack/nack_UL_hys ). If yes, then the process is transferred back to step 1016. If no, then at step 1026, SPS UL/DL grant CQI SRS ,DL/UL HARQ ACK/NACK are aligned as per figure 4.a and 4.b, back in the dynamic feedback reporting mode which is configured using PDCCH or downlink common control channel.

Figure 11 is a system diagram illustrating an exemplary wireless communication system, according to an embodiment of the present invention. The wireless communication system 1100 comprises of user equipment 1102 and a network 1104. The UE 1102 communicates with the network 1104 through a wireless communication medium 1106. The UE 1102 comprises of a SPS alignment module 1108. The SPS alignment module 1108 is configured for periodically exchanging control channel messages with a network during a same transmission time interval (TTI) of SRS interval; determining a time duration required for processing the exchanged control channel messages and for initiating next session of data exchange; and entering into a sleep mode for the determined time duration till the next session of data exchange is initiated. The UE may include one or more hardware components in conjunction with the SPS alignment module 1108 such as a processor, memory, a transmitter, a receiver, a removable storage, and a non-removable storage, a bus and a network interface. The functionalities of these hardware components are not mentioned in detail as it is well known to a person skilled in the art.

The present embodiments have been described with reference to specific example embodiments; it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the various embodiments. Furthermore, the various devices, modules, and the like described herein may be enabled and operated using hardware circuitry, firmware, and/or software embodied in a machine readable medium. Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.