Random access retransmission procedure
Aspects of the disclosure relate to improvements in random access procedures within a wireless communication network. To increase the likelihood that a user equipment (UE) will properly decode a random access response message from a base station, the base station may retransmit the random access response message one or more times. The number of retransmissions may be fixed or may be variable depending on whether the base station is able to receive or successfully decode a subsequently transmitted uplink message.
1. A method of wireless communication between a scheduling entity and a set of one or more scheduled entities in a wireless communication network, the method comprising:
receiving a random access preamble message during a contention-based random access procedure at the scheduling entity from a scheduled entity of the set of one or more scheduled entities;
determining a total number of retransmissions of a random access response message; splitting random access response information of a first instance of the random access
response message into a first information block and a second information block to produce a first code word based on the first information block and a second code word based on the second information block, wherein the first information block and the second information block each comprise different respective information bits of the random access response information;
including the total number of retransmissions within each of the first code word and the second code word;
transmitting the random access response message comprising the first code and the second code word from the scheduling entity to the scheduled entity in response to receiving the random access preamble message, wherein the random access response message further comprises an indication of a number of subframes to be used to subsequently retransmit the random access response message; and
automatically retransmitting the random access response message from the scheduling entity to the scheduled entity each of the total number of retransmissions utilizing the number of subframes.
2. The method of claim 1 , wherein retransmitting the random access response message from the scheduling entity to the scheduled entity further comprises:
determining a remaining number of retransmissions of the random access response message after retransmission of the random access response message; and
repeating retransmission of the random access response message from the scheduling entity to the scheduled entity based on the remaining number of retransmissions.
3. The method of claim 1 , wherein transmitting the random access response message from the scheduling entity to the scheduled entity further comprises:
transmitting, within the random access response message, an indication of a number of subframes used to transmit the random access response message.
4. The method of claim 1 , wherein determining the total number of retransmissions of the random access response message further comprises:
determining the total number of retransmissions of the random access response message and a fixed time gap between each of the retransmissions prior to receiving the random access preamble message from the scheduled entity.
5. The method of claim 4 , further comprising:
providing the fixed time gap between each of the retransmissions to the scheduled entity.
6. The method of claim 5 , wherein providing the fixed time gap between each of the retransmissions to the scheduled entity further comprises:
transmitting the fixed time gap between each of the retransmissions to the scheduled entity over a physical broadcast channel.
7. The method of claim 5 , wherein providing the fixed time gap between each of the retransmissions to the scheduled entity further comprises:
transmitting the fixed time gap between each of the retransmissions to the scheduled entity within a first random access response message.
8. The method of claim 5 , wherein providing the fixed time gap between each of the retransmissions to the scheduled entity further comprises:
transmitting the fixed time gap between each of the retransmissions to the scheduled entity within a license-assisted channel.
9. The method of claim 1 , wherein determining the total number of retransmissions of the random access response message further comprises:
measuring a signal strength of the random access preamble message; and
determining the total number of retransmissions of the random access response message based on the signal strength.
10. A scheduling entity in a wireless communication network, comprising:
a transceiver for wireless communication with a set of one or more scheduled entities; a memory; and
a processor communicatively coupled to the transceiver and the memory, the processor and the memory configured to:
receive a random access preamble message at the scheduling entity during a contention-based random access procedure from a scheduled entity of the set of one or more scheduled entities via the transceiver;
determine a total number of retransmissions of a random access response message;
split random access response information of a first instance of the random access response message into a first information block and a second information block to produce a first code word based on the first information block and a second code word based on the second information block, wherein the first information block and the second information block each comprise different respective information bits of the random access response information;
include the total number of retransmissions within each of the first code word and the second code word;
transmit the random access response message comprising the first code word and the second code word from the scheduling entity to the scheduled entity in response to receiving the random access preamble message, wherein the random access response message further comprises an indication of a number of subframes to be used to subsequently retransmit the random access response message; and
automatically retransmit the random access response message from the scheduling entity to the scheduled entity each of the total number of retransmissions utilizing the number of subframes.
11. The scheduling entity of claim 10 , wherein the processor is further configured to:
determine the total number of retransmissions of the random access response message and a fixed time gap between each of the retransmissions prior to receiving the random access preamble message from the scheduled entity.
12. The scheduling entity of claim 11 , wherein the processor is further configured to:
provide the fixed time gap between each of the retransmissions to the scheduled entity.
13. The method of claim 1 , wherein the random access response message comprises a hybrid automatic repeat request (HARQ) process identifier.