DESC:FIELD OF THE DISCLOSURE
The present subject matter is related, in general to signal processing, and more particularly, but not exclusively to a method and system for decoding a PDCCH signal.
BACKGROUND

In conventional wireless communication system, transmission equipment in a base station transmits signals throughout a geographical region known as a cell. As technology has evolved, more advanced equipment has been introduced that can provide services that were not possible in the conventional wireless communication system. Such advanced or next generation equipment may be referred as Long-Term Evolution (LTE) equipment. A traditional base station or an LTE access device provides terminals, alternatively referred as receivers/ User Equipment (UE) in the communication system, with access to other components in the communications system. The traditional base station or the LTE access device comprises a packet scheduler for dynamically allocating resources for Physical Downlink Shared Channel (PDSCH) and Physical Uplink Shared Channel (PUSCH) data transmissions and send scheduling information to the terminals through a Physical Downlink Control Channel (PDCCH).

In LTE, a Physical Downlink Control Channel (PDCCH) supports different transmission formats for the Downlink Control Information (DCI). Each terminal finds its information by blindly decoding the incoming information by trying a set of possible formats. Prior to transmission, a terminal-specific Cyclic Redundancy Check (CRC) is appended to each control message. The attached CRC is used by each terminal to find the control information. After attaching the CRC, the control information bits are encoded with a rate-1/3 tail-biting convolutional code and the rate is matched to fit the amount of resources available for PDCCH transmission by using a circular buffer. The mapping of PDCCHs to physical resource elements is subject to a certain structure which is based on so-called control channel elements (CCE). Each CCE consists of 36 physical resource elements. Based on the instantaneous channel condition and the DCI format, the PDCCH for each terminal is mapped onto a set of CCEs. Since various aggregations of the CCEs may be used for the transmission of control information, the terminal needs to blindly detect the format of the PDCCHs by testing different CCE combinations which is known as blind decoding.

The blind decoding type of adaptive modulation and coding comes at the price of a decoding delay and more importantly energy consumption in the decoder on the receiver side. Given that the receiver is a mobile station, for example mobile device with limited battery capacity, the latter is of some concern and any reduction in the decoding complexity incurred by the blind decoding strategy would be valuable.

One of the conventional methods as disclosed in US20120263134 addresses the above said issue of reducing the decoding complexity on the receiver side. The method includes estimating a suitable sized CCE segment in a PDCCH signal, generating a tree structure which contains CCE aggregation levels of the estimated CCE segment, arranging the aggregation levels in a hierarchal order and then decoding the PDCCH signal by using boundaries defined by the tree structure, wherein the boundaries form a search path, enabling a reduced search for a blind decode.

Another conventional method disclosed in EP 2335372 A1 addresses the above said issue of improving the performance of the telecommunication system by selecting which control channel element(s) to use for a PDCCH comprising the sub-frame. In order to determine which control channel element(s) to use for a PDCCH, the selector configured at base station prepares a cost matrix to express, for each potential combination of control channel element(s), a number of resource element groups residing in each symbol of a control portion of the sub-frame; determines which of the potential combinations of control channel element(s) is a valid combination of control channel element(s) and evaluates a cost function C(j) for each valid combination (j) of control channel element(s) over symbols comprising a control portion of the sub-frame.

Both these conventional methods disclose the concept of selecting a control channel for the PDCCH to reduce the number of iterations at the terminal. But to select the control channel element for decoding the DCI, the terminal has to perform plurality of operations which increases the overhead on the terminal and the processing requirements.
Thus, there exists need for a method and system to reduce the number of iterations in blind decoding at the mobile station or mobile station overcoming the above mentioned drawbacks.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the prior art are overcome and additional advantages are provided through the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
Accordingly, the present disclosure relates to a method of decoding a physical downlink control channel (PDCCH) signal transmitted by a base station to one or more mobile stations communicating with the base station through a communication network. The method comprises steps of generating a plurality of channel control element (CCE) information units corresponding to each of the one or more mobile stations. The plurality of CCE information units is generated at the base station. Further, the method comprises creating a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) using the plurality of CCE information unit at the base station. The method further comprising scrambling, at the base station, a Cyclic Redundancy Check (CRC) of Data Control Information (DCI) using a CCE- Radio Network Temporary Identifier (CCE-RNTI), further transmitted on PDCCH and transmitting the CCE MAC-PDU in Physical Downlink Shared Channel (PDSCH) and DCI to the one or more mobile stations.
Further, the present disclosure relates to a method of decoding a physical downlink control channel (PDCCH) signal received at one or more mobile stations transmitted by a base station through a communication network. The method comprising receiving, at the one or more mobile stations, at least a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) and DCI transmitted by the base station. Upon receiving the CCE MAC-PDU and DCI, decoding, at the one or more mobile stations, a plurality of channel control element (CCE) information units based on the received CCE MAC-PDU and DCI. Each of the plurality of the CCE information units comprises at least a Cell-RNTI (C-RNTI), CCE location information and aggregation level information. The method further comprising determining, at the one or more mobile stations, whether the C-RNTI associated with the each of the decoded plurality of CCE information units matches with the RNTI configured for the one or more mobile stations and decoding, at the one or more mobile stations, at least CCE location information and aggregation level information associated with the matching CCE information unit based on the determination.
Also, the present disclosure relates to a base station for enabling decoding of a physical downlink control channel (PDCCH) signal. The base station comprises a scheduler and a processor coupled to the scheduler. The scheduler is configured to schedule one or more mobile stations and the processor is configured to generate a plurality of channel control element (CCE) information units corresponding to each of the scheduled one or more mobile stations. The processor is further configured to create a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) using the plurality of CCE information units and scramble a CRC of a Data Control Information (DCI) using a CCE- Radio Network Temporary Identifier (CCE-RNTI). The processor then transmits the CCE MAC-PDU in Physical Downlink Shared Channel (PDSCH) and DCI to the one or more mobile stations.
Furthermore, the present disclosure relates to a mobile station for enabling blind decoding of a PDCCH signal. The mobile station comprises a processor configured to receive at least a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) and DCI transmitted by the base station. The processor is further configured to decode a plurality of channel control element (CCE) information units from the received CCE MAC-PDU and DCI. Each of the plurality of the CCE information units comprises at least a Cell-RNTI (C-RNTI), CCE location information and aggregation level information. The processor is also configured to determine whether the C-RNTI associated with each of the decoded plurality of CCE information unit matches with the RNTI of the one or more mobile stations and decode at least CCE location information and aggregation level information associated with the matching CCE information unit, based on the determination.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:
Figure 1 illustrates a system for decoding a PDCCH signal in accordance with an embodiment of the present disclosure;
Figure 2 illustrates a base station for decoding the PDCCH signal in accordance with an embodiment of the present disclosure;
Figure 3A illustrates a Control Channel Element (CCE) - Protocol data Unit (PDU) transmitted over PDSCH in accordance with an embodiment of the present disclosure;
Figure 3B shows an exemplary CCE unit configured for mobile stations in accordance with an embodiment of the present disclosure;
Figure 4 illustrates a mobile station for decoding the PDCCH signal in accordance with an embodiment of the present disclosure;
Figure 5 show a flowchart illustrating method of decoding the PDCCH signal at a base station in accordance with an embodiment of the present disclosure; and
Figure 6 shows a flowchart illustrating method of decoding the PDCCH signal at a mobile station in accordance with an embodiment of the present disclosure.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
The present disclosure provides a method and system for reducing number of iterations in blind decoding at one or more mobile stations. According to the present invention, a base station creates a plurality of Channel control elements (CCEs) having at least a Control Channel Element (CCE) location information and aggregation level information and broadcasts the CCEs to one or more mobile stations scheduled to receive them. Each mobile station receives and decodes the CCE, and checks whether the CCE is intended for receiving at that mobile station. If the CCE is intended for receiving by that particular mobile station, then the mobile station decodes Data Control Information (DCI) based on the CCE location information and aggregation level information. Based on the decoded DCI information, data is decoded. The process of decoding the DCI using the broadcasted CCE information helps to reduce the number of iterations required during blind decoding of DCI. Thus, the claimed method and system reduces the complexity involved therein, consumes less time and resources and hence more efficient.
In the following detailed description of the embodiments of the disclosure, 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 disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, 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 disclosure. The following description is, therefore, not to be taken in a limiting sense.
Figure 1 illustrates an exemplary system for reducing complexity in blind decoding a Physical Downlink Control Channel (PDCCH) signal in wireless communication system 100.
As illustrated, the system 100 comprises a wireless communication network 102 and a base station 104 within the wireless communication network 102. The base station 104 transmits downlink signals via a transmitting antenna 106 to a plurality of mobile stations 108-1, 108-2, .. 108-N (collectively referred to as mobile station 108) that receives the downlink signals through a plurality of receiving antennas 110-1, 110-2, .. 110-N (collectively referred to as receiving antenna 110). A person skilled in the art would understand that the network generally includes multiple base stations 104, individually or cooperatively which supports potentially many mobile stations 108 (alternatively referred to as mobile stations 108).

In an embodiment, the network 102 is configured as per long term evolution (LTE) standards and the base station 104 and the mobile station 108 are configured for LTE operation. In one embodiment contemplated herein, one or more of the mobile stations each include one or more processing circuits configured for efficient blind decoding as taught herein. However, those skilled in the art will recognize that these processing circuits can be implemented in other types of mobile stations (mobile or stationary) and will further recognize that the term "mobile station" is to be construed broadly. As used herein, the term mobile station includes, but is not limited, to cellular radiotelephones, pagers, PDAs, laptop/palmtop computers, network access cards, and essentially any other device that includes a mobile station.

To facilitate communications, a plurality of different communication channels are established between the base station 104 and the mobile station 108. In LTE no dedicated data channels are used, instead shared channel resources are used in both downlink and uplink. These shared resources, the downlink shared channel and the uplink shared channel are each controlled by one or more schedulers that assigns different parts of the downlink and uplink shared channels to different mobile stations for reception and transmission respectively. The important channels between the base station 104 and the mobile station 108 include a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH) and a Physical Uplink Shared Channel (PUSCH). The PDCCH is a channel that allows the base station 104 to control the mobile station 108 during downlink data communications. Each assignment for downlink shared channel or uplink shared channel is transmitted on the PDCCH in the control region in DCI. There are typically multiple PDCCHs in each sub-frame, and each mobile station will be required to monitor the PDCCHs to be able to monitor a subset of the PDCCHs. The PDCCH is also used to transmit scheduling or control data packets which are also referred to as downlink control information (DCI) packets to the mobile station 108. The DCI packets inform the mobile station 108 about the modulation and coding scheme, transport block size, precoding information, hybrid- Automatic Repeat Request (ARQ) information, mobile station identifier, Carrier Indicator Function etc. using which the mobile station 108 decodes the downlink data transmissions.

A separate DCI packet may also be transmitted by the base station 104 to the mobile station 108 for each sub-frame transmission. The PUSCH is used by base station 104 to transmit the data sub-frames to the mobile stations 108. The PDSCH is the main data bearing channel which is allocated to the mobile stations 108 on a dynamic basis. The PDSCH carries data in Transport Blocks (TB) which correspond to a media access control-protocol data unit (MAC PDU). They are passed from the MAC layer to the physical layer once per Transmission Time Interval (TTI), for example, the TTI is 1 millisecond.

The PDCCH comprises a plurality of control channel elements (CCEs) that are used to transmit DCI formatted messages from the base station 104 to the mobile stations 108. Each CCE consists of thirty six Resource elements (REs) and the PDCCH comprises an aggregation of 1, 2, 4 or 8 CCEs. The base station 104 may select one CCE or an aggregation of CCEs to be used to transmit the DCI message depending upon the communication link condition between the base station 104 and the mobile stations 105. The number of consecutive CCEs required to carry one PDCCH is called "Aggregation Level'. A CCE subset that includes one CCE will be referred to as "Aggregation level 1" subsets. Similarly, subsets that include two CCEs will be referred to as "Aggregation level 2" subsets, subsets that include four CCEs will be referred to as "Aggregation level 4" subsets, and subsets that include eight CCEs will be referred to as "Aggregation level 8" subsets. Thus, number of consecutive CCEs required to carry one PDCCH depends on the format of the PDCCH. The relationship between PDCCH format and the number CCE required to carry the PDCCH is as follows:
PDCCH Format 0: Requires 1 CCE = Aggregation Level 1
PDCCH Format 1: Requires 2 CCE = Aggregation Level 2
PDCCH Format 2: Requires 4 CCE = Aggregation Level 4
PDCCH Format 3: Requires 8 CCE = Aggregation Level 8

Each CCE may only be utilized on one aggregation level at the time. The variable size achieved by the different aggregation levels is used to adapt the coding rate for each PDCCH. The total number of available CCEs in a sub-frame will vary depending on several parameters including number of OFDM symbols used for PDCCH, number of antennas, system bandwidth, etc. CCEs and their constituent REs are spread out, both in time over the OFDM symbols used for PDCCH and in frequency over the configured bandwidth. This is achieved through a number of operations including interleaving, and cell-specific cyclic shifts etc. These operations also serve the purpose of randomizing the mapping between different cells. All these operations are entirely known to the mobile station 108.

In one embodiment, the base station 104 generates a CCE Media Access Control- Protocol Data Unit (CCE-MAC PDU) 112 and transmits to the mobile station 108. As illustrated in Figure 2, the base station 104 includes a central processing unit (“CPU” or “processor”) 202, one or more interfaces and a memory 204. The processor 202 may comprise at least one data processor for executing program components and for executing user- or system-generated queries. The processor may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. The processor may include a microprocessor, such as AMD Athlon, Duron or Opteron, ARM’s application, embedded or secure processors, IBM PowerPC, Intel’s Core, Itanium, Xeon, Celeron or other line of processors, etc. The processor may be implemented using mainframe, distributed processor, multi-core, parallel, grid, or other architectures. Some embodiments may utilize embedded technologies like application-specific integrated circuits (ASICs), digital signal processors (DSPs), Field Programmable Gate Arrays (FPGAs), etc. Among other capabilities, the processor is configured to fetch and execute computer-readable instructions stored in the memory.

The interface(s) may include a variety of software and hardware interfaces, for example, an I/O interface 206, a network interface 208, a storage interface 210, etc. The I/O interface 206 is coupled with the processor and one or more Input / Output (I/O) devices 212. The I/O device 212 is configured to receive communication signal from the base station 104 via the I/O interface 206 and transmit outputs or results for displaying in the I/O device 212 via the I/O interface 206. The I/O interface 206 may employ communication protocols/methods such as, without limitation, audio, analog, digital, monaural, RCA, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS/2, BNC, coaxial, component, composite, digital visual interface (DVI), high-definition multimedia interface (HDMI), RF antennas, S-Video, VGA, IEEE 802.n /b/g/n/x, Bluetooth, cellular (e.g., code-division multiple access (CDMA), high-speed packet access (HSPA+), global system for mobile communications (GSM), long-term evolution (LTE), WiMax, or the like), etc.

The network interface 208 can facilitate multiple communications within a wide variety of networks and protocol types, including wired networks, for example LAN, cable, etc., and wireless networks such as WLAN, cellular, or satellite. The interface(s) may include one or more ports for connecting a number of devices to each other or to another server.

The processor 202 may be disposed in communication with one or more memory devices (e.g., RAM 214, ROM 216, etc.) via a storage interface 210. The storage interface 210 may connect to memory devices including, without limitation, memory drives, removable disc drives, etc., employing connection protocols such as serial advanced technology attachment (SATA), integrated drive electronics (IDE), IEEE-1394, universal serial bus (USB), fiber channel, small computer systems interface (SCSI), etc. The memory drives may further include a drum, magnetic disc drive, magneto-optical drive, optical drive, redundant array of independent discs (RAID), solid-state memory devices, solid-state drives, etc.

In one implementation, the memory stores information which includes, but is not limited to CCE-RNTI, plurality of CCE information units, CCE MAC-PDU and DCI. In an embodiment, the memory may be implemented as a volatile memory device utilized by various elements of the virtual service management system (e.g., as off-chip memory). For these implementations, the memory 204 may include, but is not limited to, random access memory (RAM), dynamic random access memory (DRAM) or static RAM (SRAM). In some embodiment, the memory 204 may include any of a Universal Serial Bus (USB) memory of various capacities, a Compact Flash (CF) memory, an Secure Digital (SD) memory, a mini SD memory, an Extreme Digital (XD) memory, a memory stick, a memory stick duo, an Smart Media Cards (SMC) memory, an Multimedia card (MMC) memory, and an Reduced-Size Multimedia Card (RS-MMC), for example, noting that alternatives are equally available. Similarly, the memory may be of an internal type included in an inner construction of a corresponding mobile station 108, or an external type disposed remote from such a mobile station 108. Again, the memory 204 may support the above-mentioned memory types as well as any type of memory that is likely to be developed and appear in the near future, such as phase change random access memories (PRAMs), units, buzzers, beepers etc. The one or more units generate a notification for indicating the identified ferroelectric random access memories (FRAMs), and magnetic random access memories (MRAMs), for example.

The base station 104 further comprises a scheduler 218 coupled with the processor 202. The scheduler 218 is configured for scheduling the mobile station 108 intended for receiving the CCE-MAC PDU 112 transmitted by the base station 104 in the downlink transmission via transmitter/receiver antenna 106. As illustrated in Figure 3A, the processor 202 generates a plurality of CCE information units 302-1, 302-2, 302-3, … 302-N (collectively referred to as 302) corresponding to each of the scheduled mobile station 108 configured in the network 102. An exemplary structure of CCE information units 302 generated by the base station 104 is illustrated in Figure 3B.

Each CCE information unit 302 comprises three fields including a header field which is a 16-bit C-RNTI 304 (Cell-Radio Network Temporary Identifier). The header field provides information about the mobile station 108 which is intended to receive and use the CCE information unit 302 for decoding. The C-RNTI information 304 is available at both the base station 104 and the mobile station 108. The second field is an 8 bit CCE information field which provides CCE location information 306. The third field is a 2 bit aggregation level field which provides aggregation level information 308. The processor obtains CCE location information 306 and aggregation level information 308 for each of the scheduled mobile station 108 from the scheduler and generates the plurality of CCE information units. The processor concatenates the plurality of generated CCE information units 302 to form the CCE-MAC PDU 112.

The processor also forms the DCI format 1A for the CCE RNTI containing resource allocation information for CCE MAC-PDU 112. The DCI format 1A is chosen for allocation of a dedicated signature to a mobile station 108 for random access of the DCI. Upon forming the DCI format, the processor scrambles a Cyclic Redundancy Code (CRC) of the DCI with the CCE-RNTI in the chosen DCI 1A format within a common search space. In one embodiment, the processor identifies the CCE-RNTI and encodes the DCI in the predetermined DCI 1A format. Thereafter, the base station 104 transmits the CCE MAC-PDU 112 in PDSCH signal with DCI transmitted in PDCCH via the transmitting antenna 106.

The mobile station 108 receives the PDSCH signal via the receiving antenna 110 and decodes the CCE MAC-PDU 112 and DCI 1A from the received PDSCH signal. As illustrated in Figure 4, the base station 104 includes a central processing unit (“CPU” or “processor”) 402, one or more interfaces and a memory 404. The processor 402 may comprise at least one data processor for executing program components and for executing user- or system-generated queries. The processor may include specialized processing units such as integrated system (bus) controllers, memory management control units, floating point units, graphics processing units, digital signal processing units, etc. The processor may include a microprocessor, such as AMD Athlon, Duron or Opteron, ARM’s application, embedded or secure processors, IBM PowerPC, Intel’s Core, Itanium, Xeon, Celeron or other line of processors, etc. The processor may be implemented using mainframe, distributed processor, multi-core, parallel, grid, or other architectures. Some embodiments may utilize embedded technologies like application-specific integrated circuits (ASICs), digital signal processors (DSPs), Field Programmable Gate Arrays (FPGAs), etc. Among other capabilities, the processor is configured to fetch and execute computer-readable instructions stored in the memory.

The interface(s) may include a variety of software and hardware interfaces, for example, an I/O interface 406, a network interface 408, a storage interface 410, etc. The I/O interface 406 is coupled with the processor and one or more Input / Output (I/O) devices 412. The I/O device 412 is configured to receive communication signal from the base station 104 via the I/O interface 406 and transmit outputs or results for displaying in the I/O device 412 via the I/O interface 406. The I/O interface 406 may employ communication protocols/methods such as, without limitation, audio, analog, digital, monaural, RCA, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS/2, BNC, coaxial, component, composite, digital visual interface (DVI), high-definition multimedia interface (HDMI), RF antennas, S-Video, VGA, IEEE 802.n /b/g/n/x, Bluetooth, cellular (e.g., code-division multiple access (CDMA), high-speed packet access (HSPA+), global system for mobile communications (GSM), long-term evolution (LTE), WiMax, or the like), etc.

The network interface 408 can facilitate multiple communications within a wide variety of networks and protocol types, including wired networks, for example LAN, cable, etc., and wireless networks such as WLAN, cellular, or satellite. The interface(s) may include one or more ports for connecting a number of devices to each other or to another server.

The processor 402 may be disposed in communication with one or more memory devices (e.g., RAM 414, ROM 416, etc.) via a storage interface 410. The storage interface 410 may connect to memory devices including, without limitation, memory drives, removable disc drives, etc., employing connection protocols such as serial advanced technology attachment (SATA), integrated drive electronics (IDE), IEEE-1394, universal serial bus (USB), fiber channel, small computer systems interface (SCSI), etc. The memory drives may further include a drum, magnetic disc drive, magneto-optical drive, optical drive, redundant array of independent discs (RAID), solid-state memory devices, solid-state drives, etc.

In one implementation, the memory stores information which includes, but is not limited to OFDM symbols, C-RNTI etc. In an embodiment, the memory may be implemented as a volatile memory device utilized by various elements of the virtual service management system (e.g., as off-chip memory). For these implementations, the memory 404 may include, but is not limited to, random access memory (RAM), dynamic random access memory (DRAM) or static RAM (SRAM). In some embodiment, the memory 404 may include any of a Universal Serial Bus (USB) memory of various capacities, a Compact Flash (CF) memory, an Secure Digital (SD) memory, a mini SD memory, an Extreme Digital (XD) memory, a memory stick, a memory stick duo, an Smart Media Cards (SMC) memory, an Multimedia card (MMC) memory, and an Reduced-Size Multimedia Card (RS-MMC), for example, noting that alternatives are equally available. Similarly, the memory may be of an internal type included in an inner construction of a corresponding mobile station 108, or an external type disposed remote from such a mobile station 108. Again, the memory 404 may support the above-mentioned memory types as well as any type of memory that is likely to be developed and appear in the near future, such as phase change random access memories (PRAMs), units, buzzers, beepers etc. The one or more units generate a notification for indicating the identified ferroelectric random access memories (FRAMs), and magnetic random access memories (MRAMs), for example.

In one embodiment, the processor 402 decodes the CCE MAC-PDU 112 from the received PDSCH signal. The processor 402 buffers one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols received for each sub-frame of the PDSCH signal, for example, 1ms and processes the buffered symbols. In the time domain, one sub-frame of 1 ms duration is divided into 12 or 14 OFDM symbols depending on the configuration. One OFDM symbol comprises a number of sub-carriers in the frequency domain depending on channel bandwidth and configuration. Four Resource Element is referred to as a Resource Element Group (REG), each REG comprises a Physical Control Format Identifier Channel (PCFICH). In one implementation, the processor 402 obtains the OFDM symbols and extracts one or more REGs at least from a first OFDM symbol or sample. Based on the PCFICH of the extracted REG, the processor 402 determines control format indicator (CFI) information and determines the plurality of CCE information units 302 associated with the PDCCH signal based on the CFI information. The processor 402 groups the plurality of determined CCE information units 302 into a CCE buffer.
The processor 402 searches the CCE buffer to identify the DCI 1A within the common search space that comprises a predetermined number of CCE information units 202 and decodes the DCI 1A using any decoding techniques known in the art. If the processor 402 successfully decodes the DCI 1A, the PDSCH signal has been transmitted without error and the decoded information is error free. In one embodiment, the base station 108 comprises an error detector 418 coupled with the processor 402 and configured to check for errors in the decoded information using for example, Cyclic Redundancy Check error detection technique. If the processor 402 is unsuccessful in decoding the DCI 1A, then the blind decoding is implemented.

Upon successful decoding of DCI 1A, the processor 402 decodes the CCE information units 302 transmitted in the PDSCH signal. In one embodiment, the processor 402 determines whether the C-RNTI 304 in the header field of each CCE information unit 302 matches with the RNTI of the mobile station 108. If the determination is TRUE, then the processor 402 uses the CCE location information 206 and the aggregation level information 308 to decode DCI. The processor 402 uses the decoded DCI to obtain allocation information in the DCI and decodes data transmitted on PDSCH using the decoded DCI information.

If the determination is FALSE, the processor 402 determines matches between C-RNTI of all the CCE information units 302 with the RNTI of the mobile station 108 till it reaches the Nth CCE information unit. If the processor 402 does not determine a match for any of the CCE information units 302, then the processor 402 determines that the CCE information unit is not intended for the mobile station 108 and the process stops.

Figure 5 illustrates a method 500 of decoding at base station 104 in accordance with an embodiment of the present invention.

The method 500 comprises one or more blocks implemented by the base station 104 for creating and transmitting CCE MAC-PDU 112. The method 500 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.
The order in which the method 500 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method 500. Additionally, individual blocks may be deleted from the method 500 without departing from the spirit and scope of the subject matter described herein. Furthermore, the method 500 can be implemented in any suitable hardware, software, firmware, or combination thereof.

At step 502, generate a plurality of CCE information units. In one embodiment, the processor of the base station 104 generates the plurality of CCE information units 302 corresponding to each mobile station 108 scheduled by the scheduler. Each CCE information unit 302 comprises three fields including a header field which is a 16-bit C-RNTI 304 (Cell-Radio Network Temporary Identifier). The header field provides information about the mobile station 108 which is intended to receive and use the CCE information unit 302 for decoding. The C-RNTI information 304 is available at both the base station 104 and the mobile station 108. The second field is an 8 bit CCE information field which provides CCE location information 306. The third field is a 2 bit aggregation level field which provides aggregation level information 308. The processor obtains CCE location information 306 and aggregation level information 308 for each of the scheduled mobile station 108 from the scheduler and generates the plurality of CCE information units 302.

At step 504, create CCE MAC-PDU. In one embodiment, the processor concatenates the plurality of generated CCE information units 302 to form the CCE-MAC PDU 112.

At step 506, scramble CRC of the DCI with CCE-RNTI. In one embodiment, the processor also forms the DCI format 1A for the CCE RNTI containing resource allocation information for CCE MAC-PDU 112. The DCI format 1A is chosen for allocation of a dedicated signature to a mobile station 108 for random access of the DCI. Upon forming the DCI format, the processor scrambles the CRC of the DCI with the CCE-RNTI in the chosen DCI 1A format within a common search space. In one embodiment, the processor identifies the CCE-RNTI and encodes the DCI in the predetermined DCI 1A format. The scrambled DCI is then transmitted on PDCCH signal.
At step 508, transmit the CCE MAC-PDU with DCI. In one embodiment, the base station 104 transmits the CCE MAC-PDU 112 in PDSCH signal and DCI in PDCCH via the transmitting antenna 106.

Figure 6 illustrates method 600 of decoding at the mobile station 108 in accordance with an embodiment of the present invention.

The method 600 comprises one or more blocks implemented by the mobile station 108 for receiving and decoding PDSCH signal containing CCE MAC-PDU 112 and encoded DCI 1A. The method 600 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.

The order in which the method 600 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method 600. Additionally, individual blocks may be deleted from the method 600 without departing from the spirit and scope of the subject matter described herein. Furthermore, the method 600 can be implemented in any suitable hardware, software, firmware, or combination thereof.

At step 602, receive CCE MAC-PDU and DCI. In one embodiment, the mobile station 108 receives the CCE MAC-PDU in the PDSCH signal and DCI via the receiving antenna 110.

At step 604, decode CCE MAC-PDU and obtain plurality of CCE information units. In one embodiment, the processor decodes the CCE MAC-PDU 112 and DCI 1A from the received PDSCH signal. In one implementation, the processor buffers one or more OFDM symbols received for each sub-frame and processes the buffered symbols. In one implementation, the processor obtains the OFDM symbols and extracts one or more REGs at least from a first OFDM symbol or sample. Based on the PCFICH in the extracted REG, the processor determines control format indicator (CFI) information and determines the plurality of CCE information units 302 associated with the PDCCH signal based on the CFI information. The processor groups the plurality of determined CCE information units 302 into the CCE buffer. The processor searches the CCE buffer to identify the DCI 1A within the common search space and decodes the DCI 1A using any decoding techniques known in the art. If the processor successfully decodes the DCI 1A, the PDSCH signal has been transmitted without error and the decoded information is error free. If the processor is unsuccessful in decoding the DCI 1A, then the blind decoding is implemented.

At step 606, determine as to whether the C-RNTI of the CCE information unit matches with the RNTI of the mobile station. In one embodiment, if the determination is TRUE, then the method proceeds to block 608 via the “YES” path; otherwise proceeds to block 610 via the “NO” path.

At step 608, decode data using information associated with the matching CCE information unit. In one embodiment, if it is determined that the C-RNTI of the CCE information unit 202 matches with the RNTI of the mobile station 108, then the processor uses the CCE location information 306 and the aggregation level information 308 to decode DCI. The processor uses the decoded DCI to obtain allocation information in the DCI and decodes data transmitted on PDSCH using the decoded DCI information.

At step 610, determine as to whether all CCE information units have been checked for match. In one embodiment, if it is determined that the C-RNTI of the CCE information unit 302 does not match with the RNTI of the mobile station 108, then the processor determines whether all CCE information units 302 have been checked. If the determination is TRUE, then the method proceeds to block 612 via the “YES” path; otherwise proceeds to block 606 via the “NO” path to again determine the match till all the CCE information units are checked for match.

At step 612, stop the process since the CCE information unit intended for the mobile station is not found. In one embodiment, if the processor does not determine a match for any of the CCE information units 302, then the processor determines that the CCE information unit is not intended for the mobile station 108 and stops the process.

Advantages of the embodiment of the present disclosure are illustrated herein.
Embodiments of the present disclosure decodes PDCCH signal using comparatively less number of components. Hence, the system is economical. Since the number of components involved in decoding the PDCCH signal resulting into reduction in consumption of power required for decoding.

In one embedment, since the CCE location information and aggregation level information is known accurately, the possibility of decoding DCI is high, hence the number of iterations required in decoding the signal at the mobile station is reduced. Since the number of iterations is reduced, the processing requirement is also reduced. Thus, processing overhead is reduced and speed of the process is increased.

The described operations may be implemented as a method, system or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The described operations may be implemented as code maintained in a “non-transitory computer readable medium”, where a processor may read and execute the code from the computer readable medium. The processor is at least one of a microprocessor and a processor capable of processing and executing the queries. A non-transitory computer readable medium may comprise media such as magnetic storage medium (e.g., hard disk drives, floppy disks, tape, etc.), optical storage (CD-ROMs, DVDs, optical disks, etc.), volatile and non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, Flash Memory, firmware, programmable logic, etc.), etc. Further, non-transitory computer-readable media comprise all computer-readable media except for a transitory. The code implementing the described operations may further be implemented in hardware logic (e.g., an integrated circuit chip, Programmable Gate Array (PGA), Application Specific Integrated Circuit (ASIC), etc.).

Still further, the code implementing the described operations may be implemented in “transmission signals”, where transmission signals may propagate through space or through a transmission media, such as an optical fiber, copper wire, etc. The transmission signals in which the code or logic is encoded may further comprise a wireless signal, satellite transmission, radio waves, infrared signals, Bluetooth, etc. The transmission signals in which the code or logic is encoded is capable of being transmitted by a transmitting station and received by a receiving station, where the code or logic encoded in the transmission signal may be decoded and stored in hardware or a non-transitory computer readable medium at the receiving and transmitting stations or devices. An “article of manufacture” comprises non-transitory computer readable medium, hardware logic, and/or transmission signals in which code may be implemented. A device in which the code implementing the described embodiments of operations is encoded may comprise a computer readable medium or hardware logic. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the invention, and that the article of manufacture may comprise suitable information bearing medium known in the art.

The terms "an embodiment", "embodiment", "embodiments", "the embodiment", "the embodiments", "one or more embodiments", "some embodiments", and "one embodiment" mean "one or more (but not all) embodiments of the invention(s)" unless expressly specified otherwise.

The terms "including", "comprising", “having” and variations thereof mean "including but not limited to", unless expressly specified otherwise.

The enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise.

The terms "a", "an" and "the" mean "one or more", unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.

When a single device or article is described herein, it will be readily apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be readily apparent that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.

The illustrated operations of Figures 5 and 6 show certain events occurring in a certain order. In alternative embodiments, certain operations may be performed in a different order, modified or removed. Moreover, steps may be added to the above described logic and still conform to the described embodiments. Further, operations described herein may occur sequentially or certain operations may be processed in parallel. Yet further, operations may be performed by a single processing unit or by distributed processing units.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

It is intended that the disclosure and examples be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.
,CLAIMS:1. A method of decoding a physical downlink control channel (PDCCH) signal transmitted by a base station to one or more mobile stations communicating with the base station through a communication network, the method comprising:
generating, at the base station, a plurality of channel control element (CCE) information units corresponding to each of the one or more mobile stations;
creating, at the base station, a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) using plurality of CCE information unit;
scrambling, at the base station, a Cyclic Redundancy Check (CRC) of Data Control Information (DCI) using a CCE- Radio Network Temporary Identifier (CCE-RNTI); and
transmitting the CCE MAC-PDU with the DCI in Physical Downlink Shared Channel (PDSCH) to the one or more mobile stations.

2. The method as claimed in claim 1, wherein the CCE MAC-PDU is created by concatenating the plurality of CCE information units.

3. The method as claimed in claim 1, wherein scrambling the CRC of the DCI comprising identifying, at the base station, the CCE-RNTI and encoding the DCI using the identified CCE-RNTI in a predetermined DCI format.

4. The method as claimed in claim 1, wherein each of the plurality of the CCE information units comprises at least a Cell-RNTI (C-RNTI), CCE location information and aggregation level information.

5. The method as claimed in claim 1, wherein the DCI is encoded in a predetermined format for allocating resources to the one or more mobile stations.

6. A method of decoding a physical downlink control channel (PDCCH) signal received at one or more mobile stations transmitted by a base station through a communication network, the method comprising:
receiving, at the one or more mobile stations, at least a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) and DCI transmitted by the base station in a Physical Downlink Shared Channel (PDSCH) downlink transmission;
decoding, at the one or more mobile stations, a plurality of channel control element (CCE) information units from the received CCE MAC-PDU and DCI, wherein each of the plurality of the CCE information units comprises at least a Cell-RNTI (C-RNTI), CCE location information and aggregation level information;
determining, at the one or more mobile stations, whether the C-RNTI associated with the each of the decoded plurality of CCE information units matches with the RNTI configured for the one or more mobile stations; and
based on the determination, decoding, at the one or more mobile stations, at least CCE location information and aggregation level information associated with the matching CCE information unit.

7. The method as claimed in claim 6, further comprising obtaining one or more Orthogonal Frequency Division Multiplexing (OFDM) samples of the received CCE MAC PDU and grouping the one or more OFDM samples thus obtained.

8. The method as claimed in claim 7, wherein decoding the plurality of CCE information units from the received CCE MAC-PDU and DCI comprising:
extracting one or more Resource Element Groups (REGs) at least from a first OFDM sample, wherein each of the one or more REGs comprises a Physical Control Format Identifier Channel (PCFICH);
determining control format indicator (CFI) information based on the PCFICH;
determining the plurality of CCE information units associated with the PDCCH signal based on the CFI information;
grouping the plurality of determined CCE information units into a CCE buffer;
searching for a predetermined DCI format within a common search space of the CCE buffer; and
decoding the DCI format to obtain allocation information associated with CCE MAC-PDU.

9. The method as claimed in claim 6, further comprising;
decoding, at the one or more mobile stations, the DCI information from the CCE location based on the aggregation level information; and
decoding data transmitted on the PDSCH based on the decoded DCI information.

10. The method as claimed in claim 8, wherein the common search space comprises a predetermined number of CCE information units in the CCE buffer.

11. A base station for enabling decoding of a physical downlink control channel (PDCCH) signal, the base station comprising:
a scheduler for scheduling one or more mobile stations; and
a processor coupled to the scheduler and configured to:
generate a plurality of channel control element (CCE) information units corresponding to each of the scheduled one or more mobile stations;
create a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) using the plurality of CCE information units;
scramble a CRC of a Data Control Information (DCI) using a CCE- Radio Network Temporary Identifier (CCE-RNTI); and
transmit the CCE MAC-PDU with the DCI in Physical Downlink Shared Channel (PDSCH) to the one or more mobile stations.

12. The base station as claimed in claim 11, wherein the processor is configured to create the CCE MAC-PDU by concatenating the plurality of CCE information units.

13. The base station as claimed in claim 11, wherein each of the plurality of the CCE information units comprises at least a Cell - Radio Network Temporary Identifier (C-RNTI), CCE location information and aggregation level information.

14. The base station as claimed in claim 11, wherein the processor is configured to scramble the DCI by identifying the CCE-RNTI and encoding the DCI using the identified CCE-RNTI in a predetermined DCI format.

15. A mobile station for enabling blind decoding of a PDCCH signal, the mobile station comprising:
a processor configured to:
receive at least a CCE Media Access Control-Protocol Data Unit (CCE MAC-PDU) and DCI transmitted by the base station in a Physical Downlink Shared Channel (PDSCH) downlink transmission;
decode a plurality of channel control element (CCE) information units from the received CCE MAC-PDU and DCI, wherein each of the plurality of the CCE information units comprises at least a Cell-RNTI (C-RNTI), CCE location information and aggregation level information;
determine whether the C-RNTI associated with each of the decoded plurality of CCE information units matches with the RNTI of the one or more mobile stations;
based on the determination, decode at least CCE location information and aggregation level information associated with the matching CCE information unit.

16. The mobile station as claimed in claim 15, wherein the processor is further configured to obtain one or more Orthogonal Frequency Division Multiplexing (OFDM) samples of the received CCE MAC PDU and group the one or more OFDM samples thus obtained.

17. The mobile station as claimed in claim 16, wherein the processor is configured to decode the plurality of CCE information units from the received CCE MAC-PDU and DCI by being configured to:
extract one or more Resource Element Groups (REGs) at least from a first OFDM sample, wherein each of the one or more REGs comprises a Physical Control Format Identifier Channel (PCFICH);
determine control format indicator (CFI) information based on the PCFICH;
determine the plurality of CCE information units associated with the PDCCH signal based on the CFI information;
group the plurality of determined CCE information units into a CCE buffer;
search for a predetermined DCI format within a common search space of the CCE buffer; and
decode the DCI format to obtain allocation information associated with CCE MAC-PDU.

18. The mobile station as claimed in claim 16, wherein the processor is configured to:
decode the DCI information from the CCE location based on the aggregation level information; and
decode data transmitted on the PDSCH based on the decoded DCI information.

19. The mobile station as claimed in claim 17, wherein the common search space comprises a predetermined number of CCE information units in the CCE buffer.