Methods and apparatus for enhanced contention based access response message
Methods and apparatus for obtaining a response message for CB access uplink transmission are disclosed. In one novel aspect, UE performs a CB access uplink transmission, selects a first group of radio resources for one or more candidate control-less response message blocks with corresponding transmission repetition number, retrieves and decodes one candidate response message block corresponds to one sub-group of resources in the first group of radio resources and determines if the candidate response message is intended for the UE. In one embodiment, the UE obtains the candidate response message by determining one or more repetition number and obtaining corresponding sub-group of resources from the starting point(s). In another embodiment, the UE determines one or more frequency locations to obtain the candidate response message. In yet another embodiment, the UE selects a second group of radio resources if no response message is detected within the first group of radio resources.
1. A method comprising:
transmitting a contention based (CB) access uplink by a user equipment (UE) in a wireless network;
selecting a first group of radio resources for one or more candidate control-less response message blocks, wherein the first group of radio resources, with a first starting point, includes one or more sub-groups of radio resources and wherein each candidate control-less response message block is transmitted with a corresponding repetition number;
retrieving and decoding within each sub-group of radio resources from the first group of radio resources, wherein one candidate response message block is transmitted; and
determining if there is a candidate response message intended for the UE in response to the CB access uplink transmission.
2. The method of claim 1 , wherein the selecting of the first group of radio resource comprising: determining the first starting point to receive the one or more control-less response message blocks.
3. The method of claim 2 , wherein the first starting point is determined based on at least one of the starting-pointing-related parameters comprising: radio resources of the recent CB access uplink transmission, a repetition number of the recent CB uplink transmission, a starting point for the CB access uplink transmission, and an ending point for the CB access uplink transmission.
4. The method of claim 2 , wherein the starting point is predefined.
5. The method of claim 1 , wherein the retrieving each corresponding sub-group radio resources from the first group of radio resources comprising:
determining one or more repetition numbers for the one or more candidate control-less response message blocks;
obtaining one or more sub-groups of radio resources corresponding to the one or more repetition numbers from the one starting point.
6. The method of claim 5 wherein each repetition number is determined based on at least one of repetition-number-related parameters comprising: a repetition number of the CB access uplink transmission, and radio resources for the CB access uplink transmission.
7. The method of claim 5 , wherein a repetition-number determination rule for a response message block is based on at least one of parameters comprising: repetition number of the recent CB access uplink transmission, resources for the recent CB access uplink transmission, signal format of the recent CB access uplink transmission.
8. The method of claim 1 , wherein the retrieving each corresponding sub-group radio resources from the first group of radio resources comprising:
determining one or more frequency locations for the one or more candidate control-less response message blocks; and
obtaining one or more sub-groups of radio resources corresponding to the one or more frequency locations from the one starting point.
9. The method of claim 8 , wherein each frequency location is predefined.
10. The method of claim 8 , wherein each frequency location is based on radio resources for the CB access uplink transmission and an offset.
11. The method of claim 1 , wherein at least one subgroup of the first group of radio resources spans over one or more time blocks, wherein the one or more time blocks are discrete or contiguous.
12. The method of claim 1 , further comprising:
obtaining the control-less response message if the one or more decoded candidate response message blocks are determined as intended to the UE; otherwise: selecting a second group of radio resources by determining a second starting point, and obtaining another one or more candidate control-less response message blocks from the second group of radio resources.
13. The method of claim 12 , wherein the second group of radio resources is orthogonal to the first group of radio resources.
14. The method of claim 12 , wherein the second group of radio resources partially overlaps with the first group of radio resources.
15. The method of claim 1 , further comprising: receiving another candidate control-less response message block from the one or more candidate control-less response message blocks, by determining a second sub-group of radio resources, if the decoded candidate control-less response message block within one sub-group of radio resources is not intended for the UE in response to the CB access uplink transmission.
16. The method of claim 1 , wherein performing the CB access uplink transmission further comprising: determining a repetition number for the CB access uplink transmission, and transmitting the CB access uplink transmission with the determined repetition number over a number of time blocks.
17. The method of claim 16 , wherein the repetition number for the CB access uplink transmission is determined by a mapping rule based on one of detection parameters comprising: a detection time for synchronization acquisition, and a detection time for system information to perform the CB access uplink transmission.
18. An apparatus, comprising:
a radio frequency transceiver that transmits or receives the radio signals in a wireless communication system;
a contention based (CB) access uplink handler that transmits a CB access uplink message;
a radio resource group selector that selects a first group of radio resources for one or more candidate control-less response message blocks, wherein the first group of radio resources, with a first starting point, includes one or more sub-groups of radio resources and wherein each control-less response message is transmitted with a corresponding repetition number;
a response message handler that retrieves and decodes each sub-group of radio resources from the first group of radio resources, wherein each sub-group of radio resources corresponds to one candidate response message block; and
a determination module that determines if there is a candidate response message intended for the UE in response to the CB access uplink transmission.
19. The apparatus of claim 18 , wherein the radio resource group selector further determines a starting point to receive the one or more control-less response message blocks.
20. The apparatus of claim 19 , wherein the radio resource group selector further determines a repetition number for each corresponding control-less response message block.
21. The apparatus of claim 19 , wherein the radio resource group selector further determines a frequency location for each corresponding control-less response message block, and obtains corresponding frequency location for each control-less response message block based on the starting point.