A) TECHNICAL FIELD

[0001] The present invention generally relates to the field of cellular networks and particularly relates to long term evolution (LTE) based networks. The present invention more particularly relates to a method and system for explicitly broadcasting radio network temporary identity (RNTI), control channel element (CCE)start position and aggregation level scrambled with CCE-RNTI at a predefined CCE start position and aggregation level in physical downlink control channel (PDCCH)search space.

B) BACKGROUND OF THE INVENTION

[0002] In LTE, the user equipment (UE) decodes physical downlink control channel (PDCCH) blindly (i.e. PDCCH information is not explicit). During blind decoding of PDCCH, the UE first has to decode PDCCH at multiple CCE positions for different aggregation levels. This procedure has to be repeated for multiple radio network temporary identities(RNTIs) (if configured) and multiple Downlink Control Information (DCIs)until decoding for one or multiple RNTIs and DCIs are successful or until all available combinations are checked (in which case the UE assumes that there is no downlink transmission for that UE). This increases the power consumption at the UE as the information is not explicit. [0003] Further, when decoding the PDCCH at CCE positions, there is a possibility that PDCCH can be decoded with wrong CCE start position/aggregation level.

[0004] Hence, there is a need for amethod and system for eliminating the requirement for PDCCH blind decoding.There is also need for a method and system for removing the probability of decoding PDCCH with wrong CCE start position or aggregation leveLFurther, there is a need for reducing power consumption at the user equipments.

C) OBJECT OF THE INVENTION

[0005] The primary object of the present invention is to provide asystem and method for decoding of physical downlink control channel.

[0006] Another object of the present invention is to provide a method and system for decoding PDCCH with CCE start position/aggregation level at the mobilestation.

[0007] Another object of the present invention is to provide a method and system for removing the probability of decoding PDCCH with wrong CCE start position or aggregation level at the mobile station.

[0008] Another object of the present invention is to provide a method and system for broadcasting RNTI, CCE position and aggregation level scrambled with CCE-RNTI at a known CCE position in PDCCH search space.

[0009] Another object of the present invention is to provide a method and system for reducing excessive power consumption and probability of wrong decoding of CCE start position or aggregation level at UE during blind decoding of PDCCH.

[0010] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D) SUMMARY OF THE INVENTION

[0011] The various embodiments of the present invention provide amethod and system for eliminating the requirement for blind decoding of a Physical Downlink Control Channel (PDCCH) by broadcasting a Radio Network Temporary Identity (RNTI), a Control Channel Element (CCE) Start Position and an Aggregation Level scrambled with CCE-RNTI at a predefined CCE start position and a pre-defined aggregation level in a PDCCH search space.

[0012] According to an embodiment herein, the method comprises of obtaining a plurality of RNTI, CCE position and aggregation level from a Medium Access Control Protocol (MAC) scheduler for a plurality of User Equipments (UE), creating a plurality of CCE MAC control element for each of the plurality of user equipments, checking if sub-frame processing for the plurality of scheduled UE's is completed, creating a CCE MAC Protocol Data Unit (PDU) if the sub-frame processing is completed, scheduling the predefined Downlink Control Information (DCI) Format scrambled with the CCE-RNTI on the PDCCH at the predefined CCE start position and the aggregation level, scheduling the CCE MAC PDU on a Physical Downlink Shared Channel (PDSCH), decoding the PDCCH using the CCE-RNTI at the predefined CCE start position and the aggregation level, decoding the predefined DCI Format to obtain the CCE MAC PDU allocation information in the PDSCH, decoding the CCE MAC PDU to check if the plurality of RNTIsconfigured for the UE is scheduled in a Transmission Time Interval (TTI) for all possible DCIs, decode the RNTI, the CCE start position and the aggregation level information from CCE MAC PDU if the UE is scheduled on the RNTIs, decoding the DCIs scheduled on the PDCCH in the TTI using the corresponding RNTI, the CCE Start Position and the aggregation level combination andterminating the PDCCH decoding.

[0013] According to an embodiment of the present invention, the PDCCH decoding is performed by the UEs.

[0014] According to an embodiment of the present invention, the CCE MAC PDU is created by concatenating a plurality of CCE MAC Control Elements of the UEs scheduled in the TTI.

[0015] According to an embodiment of the present invention, the UE terminates the PDCCH decoding if the RNTI(s) configured for the UE is not scheduled in the TTI.

[0016] Embodiments herein further provide a system for decoding of a Physical Downlink Control Channel (PDCCH), the system comprises of a base station configured for obtaining a plurality of RNTI, CCE position and aggregation level from a Medium Access Control Protocol (MAC) scheduler for a plurality of User Equipments (UE), creating a CCE MAC control element for each of the plurality of user equipments, checking if sub-frame processing for the plurality of scheduled UE's is completed, creating a CCE MAC Protocol Data Unit (PDU) if the sub-frame processing is completed, scheduling the predefined Downlink Control Information (DCI) Format scrambled with the CCE-RNTI on the PDCCH at the predefined CCE start position and the aggregation levelandscheduling the CCE MAC PDU on a Physical Downlink Shared Channel (PDSCH) and a plurality of user equipments (UEs) adapted fordecoding the PDCCH using the CCE-RNTI at the predefined CCE start position and the aggregation level, decoding the predefined DCI Format to obtain the CCE MAC PDU allocation information in the PDSCH, decoding the CCE MAC PDU to check if the RNTI(s) configured for the UE is scheduled in a TTI, decode the RNTI, the CCE start position and the aggregation level information from CCE MAC PDU if the UE is scheduled on the RNTIs, decoding the DCIs scheduled on the PDCCH in the TTI using the corresponding RNTI, the CCE Start Position and the aggregation level combination andterminating the PDCCH decoding.

[0017] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

E) BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] FIG. 1 illustrates a simplified block diagram of an LTE network.

[0020] FIG. 2 is a flowchart illustrating a method for broadcasting RNTI, CCE position and aggregation level at a base station, according to an embodiment of the present invention.

[0021] FIG. 3is a flowchart illustrating a method for decoding PDCCH with CCE start position/aggregation level at the user equipment, according to an embodiment of the present invention.

[0022] Although the 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.

F) DETAILED DESCRIPTION OF THE INVENTION

[0023] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[0024] FIG. 1 illustrates a simplified block diagram of an LTE network 100. The LTE network 100 comprises a core network 101 and a radio access network (RAN) 104. The RAN 102 comprises a plurality of access nodes, which are commonly referred to evolved NodeBs (eNodeBs) 103, providing service to user equipments (UEs) 104 in respective cells of the LTE network 100. The eNodeBsl08 communicate with the UEs 104 over the air interface and provide connection to the core network 101. Although the present invention is described in the context of an LTE network, those skilled in the art will appreciate that the invention can be used in other communication networks based on the communication standards, including without limitation Wideband Code Division Multiple Access (WCDMA) networks.

[0025] In an LTE system, PDCCHs are transmitted over radio resources that are shared between several UEs. The UE is specified as having to monitor four aggregation levels, specifically, 1, 2, 4, and 8, for a UE-specific search space and two aggregation levels, specifically, 4 and 8, for a common search space.

[0026] FIG. 2 is a flowchart illustrating a method for broadcasting RNTI, CCE position and aggregation level at the base station i.e. at the transmitter end, according to an embodiment of the present invention. The method comprises the steps of getting a plurality of RNTI (Radio Network Temporary Identity), CCE (Control channel element) position and aggregation level from the MAC (Medium Access Control Protocol) scheduler for each of the scheduled UE (User Equipment); forming the plurality of CCE MAC control element for each of the scheduled UE (User Equipment); checking if processing is completed for all the UEs; upon completion, forming the CCE MAC PDU by concatenating all the CCE MAC control elements of the UEs (User Equipments) scheduled in that TTI (Transmission time interval); else forming the CCE MAC control element for the missed out scheduled UE (User Equipment); scheduling the CCE MAC PDU on PDSCH and scheduling the predefined DCI Format scrambled with CCE-RNTI on PDCCH (Physical downlink shared channel) at a predefined CCE start position and aggregation level.

[0027] According to an embodiment of the present invention, the predefined CCE aggregation level is maintained 8 for robustness.

[0028] FIG. 3 is a flowchart illustrating a method for decoding PDCCH with CCE start position/aggregation level at the mobile station i.e. at the receiver end (user equipment), according to an embodiment of the present invention. The method comprises the steps of: decoding PDCCH using CCE-RNTI at a predefined CCE start position and aggregation level at the start of the sub frame processing; decoding the predefined DCI Format to obtain CCE MAC PDU allocation information in PDSCH by the UE; decoding CCE MAC PDU to check if the RNTI(s) configured for that UE have been scheduled in this TTI by the UE; decoding the RNTI, CCE start position and aggregation level information from the CCE MAC PDU, if the UE has been scheduled on one or more RNTIs;else the PDCCH decoding is completed. Now theUE comprises complete PDCCH scheduling information. Then the UE decodes the multiple DCIs scheduled on PDCCH in that TTI using the corresponding RNTI, CCE start position and aggregation level combination.

[0029] The embodiments herein reduce excessive power consumption and remove the probability of wrong decoding of CCE Start Position/Aggregation Level at UE during the decoding of PDCCH.

[0030] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

[0031] 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.

CLAIMS
What is claimed is:

1. A method for decoding of a Physical Downlink Control Channel
(PDCCH), the method comprises of:

broadcasting a Radio Network Temporary Identity (RNTI), a Control Channel Element (CCE) Start Position and an Aggregation Level scrambled with CCE- RNTI at a predefined CCE start position and a pre-defined aggregation level in a PDCCH search space, which comprises steps of:

obtaining a plurality of RNTI, CCE position and aggregation level from a Medium Access Control Protocol (MAC) scheduler for a plurality of User Equipments (UE);

creating a plurality of CCE MAC control elements for each of the plurality of user equipments;

checking if sub-frame processing for the plurality of scheduled UE's is completed;

creating a CCE MAC Protocol Data Unit (PDU) if the sub-frame processing is completed;

scheduling the predefined Downlink Control Information (DCI) Format scrambled with the CCE-RNTI on the PDCCH at the predefined CCE start position and the aggregation level;

scheduling the CCE MAC PDU on aPhysical Downlink Shared Channel(PDSCH);

decoding the PDCCH using the CCE-RNTIat the predefined CCE start position and the aggregation level;

decodingthe predefined DCI Format to obtain the CCE MAC PDU allocation information in the PDSCH;

decoding the CCE MAC PDU to check if the RNTI(s) configured for the UE is scheduled in a Transmission Time Interval (TTI);

decode the plurality of RNTI, the CCE start position and the aggregation level information from CCE MAC PDU if the UE is scheduled on the RNTIs;

decoding the plurality of DCIs scheduled on the PDCCH in the TTI using the corresponding RNTI, the CCE Start Position and the aggregation level combination; and

terminating the PDCCH decoding.

2. The method of claim 1, wherein the PDCCH decoding is performed by the UEs.

3. The method of claim 1, wherein the CCE MAC PDU is created by concatenating a plurality of CCE MAC Control Elements of the UEs scheduled in the TTI.

4. The method of claim 1, wherein the UE terminates the PDCCH decoding if the RNTI(s) configured for the UE is notscheduled in the TTI.

5. The method of claim 1, wherein the predefined CCE aggregation level is eight.

6. A system for decoding of a Physical Downlink Control Channel (PDCCH), the system comprises of:

a base station configured for performing at least one of:

obtaining a plurality of RNTI, CCE position and aggregation level from a Medium Access Control Protocol (MAC) scheduler for a plurality of User Equipments (UE);

creating a plurality of CCE MAC control element for each of the plurality of user equipments;

checking if sub-frame processing for the plurality of scheduled UE's is completed;

creating a CCE MAC Protocol Data Unit (PDU) if the sub-frame processing is completed;

scheduling the predefined Downlink Control Information (DCI) Format scrambled with the CCE-RNTI on the PDCCH at the predefined CCE start position and the aggregation level; and

scheduling the CCE MAC PDU on aPhysical Downlink Shared Channel(PDSCH); a plurality of user equipments (UEs) adapted for:

decoding the PDCCH using the CCE-RNTIat the predefined CCE start position and the aggregation level;

decodingthe predefined DCI Format to obtain the CCE MAC PDU allocation information in the PDSCH;

decoding the CCE MAC PDU to check if the RNTI(s) configured for the UE is scheduled in a TTI;

decode the plurality of RNTI, the CCE start position and the aggregation level information from CCE MAC PDU if the UE is scheduled on the RNTIs;

decoding the plurality of DCIs scheduled on the PDCCH in the TTI using the corresponding RNTI, the CCE Start Position and the aggregation level combination; and

terminating the PDCCH decoding.