Method and apparatus for sending and receiving random access response in a wireless communication system

1. A method for wireless communication, comprising:

transmitting a random access (RA) preamble for random access; and

receiving a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

2. The method of claim 1 , wherein the second part includes the N individual RA responses arranged in same order as the N RA preamble IDs in the first part.

3. The method of claim 1 , further including:

processing the first part of the random access response to detect for an RA preamble ID of the transmitted RA preamble.

4. The method of claim 3 , where the N RA preamble IDs are arranged in increasing or decreasing order in the first part, and wherein the processing the first part includes reading the first part until an RA preamble ID in the first part is past the RA preamble ID of the transmitted RA preamble.

5. The method of claim 3 , further including:

not processing the second part of the random access response if the RA preamble ID of the transmitted RA preamble is not detected in the first part; and

processing the second part of the random access response to obtain an individual RA response for the transmitted RA preamble if the RA preamble ID is detected in the first part.

6. The method of claim 1 , wherein each individual RA response has a fixed size and includes one of a timing advance, an uplink grant, and a temporary Cell Radio Network Temporary Identifier (C-RNTI) for one user equipment (UE).

7. The method of claim 1 , wherein the receiving the random access response includes

receiving a Medium Access Control (MAC) protocol data unit (PDU) comprising including a MAC header and a MAC payload,

obtaining the first part of the random access response from the MAC header, and

obtaining the second part of the random access response from the MAC payload.

8. The method of claim 7 , wherein the receiving the random access response further includes

processing the MAC PDU with a Random Access Radio Network Temporary Identifier (RA-RNTI) applicable for a set of user equipments (UEs), and

identifying the MAC PDU as carrying the random access response if the processing with the RA-RNTI is successful.

9. The method of claim 1 , wherein the receiving the random access response includes

receiving a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload,

identifying the MAC PDU as carrying the random access response based on a predefined value for a designated field of the MAC header, and

obtaining the first and second parts of the random access response from the MAC payload if the MAC PDU carries the random access response.

10. An apparatus for wireless communication, comprising:

at least one processor configured to transmit a random access (RA) preamble for random access, and to receive a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part comprise includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

11. The apparatus of claim 10 , wherein the at least one processor is configured to process the first part of the random access response to detect for an RA preamble ID of the transmitted RA preamble, to not process the second part of the random access response if the RA preamble ID of the transmitted RA preamble is not detected in the first part, and to process the second part of the random access response to obtain an individual RA response for the transmitted RA preamble if the RA preamble ID is detected in the first part.

12. The apparatus of claim 10 , wherein the at least one processor is configured to receive a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload, to obtain the first part of the random access response from the MAC header, and to obtain the second part of the random access response from the MAC payload.

13. The apparatus of claim 10 , wherein the at least one processor is configured to receive a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload, to identify the MAC PDU as carrying the random access response based on a predefined value for a designated field of the MAC header, and to obtain the first and second parts of the random access response from the MAC payload if the MAC PDU carries the random access response.

14. An apparatus for wireless communication, comprising:

means for transmitting a random access (RA) preamble for random access; and

means for receiving a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

15. The apparatus of claim 14 , further including:

means for processing the first part of the random access response to detect for an RA preamble ID of the transmitted RA preamble;

means for not processing the second part of the random access response if the RA preamble ID of the transmitted RA preamble is not detected in the first part; and

means for processing the second part of the random access response to obtain an individual RA response for the transmitted RA preamble if the RA preamble ID is detected in the first part.

16. The apparatus of claim 14 , wherein the means for receiving the random access response includes

means for receiving a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload,

means for obtaining the first part of the random access response from the MAC header, and

means for obtaining the second part of the random access response from the MAC payload.

17. The apparatus of claim 14 , wherein the means for receiving the random access response includes

means for receiving a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload,

means for identifying the MAC PDU as carrying the random access response based on a predefined value for a designated field of the MAC header, and

means for obtaining the first and second parts of the random access response from the MAC payload if the MAC PDU carries the random access response.

18. A computer program product, comprising:

a non-transitory computer-readable medium comprising:

code for causing at least one computer to transmit a random access (RA) preamble for random access, and

code for causing the at least one computer to receive a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

19. The computer program product of claim 18 , wherein the non-transitory computer-readable medium further includes:

code for causing the at least one computer to process the first part of the random access response to detect for an RA preamble ID of the transmitted RA preamble;

code for causing the at least one computer to not process the second part of the random access response if the RA preamble ID of the transmitted RA preamble is not detected in the first part; and

code for causing the at least one computer to process the second part of the random access response to obtain an individual RA response for the transmitted RA preamble if the RA preamble ID is detected in the first part.

20. A method for wireless communication, comprising:

receiving at least one random access (RA) preamble from at least one user equipment (UE) for random access; and

transmitting a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

21. The method of claim 20 , further including:

arranging the N RA preamble IDs in increasing or decreasing order in the first part.

22. The method of claim 20 , wherein the second part includes the N individual RA responses arranged in same order as the N RA preamble IDs in the first part, and wherein each individual RA response has a fixed size and includes one of a timing advance, an uplink grant, and a temporary Cell Radio Network Temporary Identifier (C-RNTI) for one UE.

23. The method of claim 20 , wherein the sending the random access response includes

generating a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload,

mapping the first part of the random access response to the MAC header, and

mapping the second part of the random access response to the MAC payload.

24. The method of claim 23 , wherein the sending the random access response further includes

processing the MAC PDU with a Random Access Radio Network Temporary Identifier (RA-RNTI) applicable for a set of user equipments (UEs), the RA-RNTI being used to identify the MAC PDU as carrying the random access response.

25. The method of claim 20 , wherein the sending the random access response includes

generating a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload,

setting a designated field of the MAC header to a predefined value to indicate the MAC PDU carrying the random access response, and

mapping the first and second parts of the random access response to the MAC payload.

26. The method of claim 20 , wherein the receiving the at least one RA preamble includes receiving the at least one RA preamble in at least one subframe, and wherein the transmitting the random access response includes transmitting the random access response asynchronously within a predetermined time window of each of the N RA preambles being responded to by the random access response.

27. An apparatus for wireless communication, comprising:

at least one processor configured to receive at least one random access (RA) preamble from at least one user equipment (UE) for random access, and to transmit a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

28. The apparatus of claim 27 , wherein the at least one processor is configured to generate a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload, to map the first part of the random access response to the MAC header, and to map the second part of the random access response to the MAC payload.

29. The apparatus of claim 27 , wherein the at least one processor is configured to generate a Medium Access Control (MAC) protocol data unit (PDU) including a MAC header and a MAC payload, to set a designated field of the MAC header to a predefined value to indicate the MAC PDU carrying the random access response, and to map the first and second parts of the random access response to the MAC payload.

30. A computer program product, comprising:

a non-transitory computer-readable medium comprising:

code for causing at least one computer to receive at least one random access (RA) preamble from at least one user equipment (UE) for random access; and

code for causing the at least one computer to transmit a random access response including a first part and a second part, the first part including a list of N RA preamble identifiers (IDs) for N RA preambles being responded to by the random access response, and the second part including N individual RA responses for the N RA preambles, where N is a value of one or greater, wherein the first part includes N entries, each entry including an extension (E) field and an RA preamble ID field, the extension field being set to a first value to indicate another entry will follow in the first part or a second value to indicate no other entry will follow in the first part, and the RA preamble ID field carrying an RA preamble ID of an RA preamble being responded to by the random access response, wherein the first part includes a header and the second part includes a payload.

31. The computer program product of claim 30 , wherein the second part includes the N individual RA responses arranged in same order as the N RA preamble IDs in the first part, and wherein each individual RA response has a fixed size and includes one of a timing advance, an uplink grant, and a temporary Cell Radio Network Temporary Identifier (C-RNTI) for one UE.