Random access procedures for machine-type communications

Patent metadata

Field	Value
Publication number	US-9924542-B2
Application number	US-201514670507-A
Country	US
Kind code	B2
Filing date	Mar 27, 2015
Priority date	Mar 27, 2014
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

Systems and methods relating to transmission and reception of a Random Access Response (RAR) message to a wireless device (e.g., a User Equipment (UE)) in a manner that is particularly well-suited for, but not limited to, reduced bandwidth devices, such as Machine Type Communication (MTC) devices, are disclosed. In some embodiments, a method of operation of a wireless device to perform random access to a cellular communications network comprises transmitting a random access preamble on a physical random access channel and determining, from a random access preamble index of the random access preamble, one of a random access response resource and a channel to monitor for a transmission of an indication of the random access response resource. The method further comprises receiving a random access response on the random access response resource.

First claim

What is claimed is:

1. A method of operation of a reduced bandwidth wireless device to perform random access to a cellular communications network, the method comprising:
transmitting a random access preamble on a physical random access channel;
determining, from a random access preamble index of the transmitted random access preamble, one of a random access response resource and a channel to monitor for a transmission of an indication of the random access response resource, wherein determining the random access response resource comprises determining the random access response resource from the random access preamble index according to a predefined mapping of random access preamble indices and random access response resources; and
receiving a random access response on the random access response resource,
wherein the random access response resource determined from the random access preamble index is valid for a single subframe determined from the random access preamble index, and receiving the random access response on the random access response resource comprises receiving the random access response on the random access response resource in the single subframe.

2. The method of claim 1 wherein the predefined mapping is a function of cell index.

3. The method of claim 1 wherein the predefined mapping is such that two or more of the random access preamble indices are mapping to the random access response resource.

4. The method of claim 1 wherein the predefined mapping is such that the random access preamble index maps to different random access response resources in different subframes.

5. The method of claim 1 wherein determining, from the random access preamble index, one of the random access response resource and the channel to monitor for the transmission of the indication of the random access response resource comprises:
determining the channel to monitor for the transmission of the indication of the random access response resource from the random access preamble index.

6. The method of claim 5 wherein determining the channel to monitor for the indication of the random access response resource comprises determining the channel to monitor for the indication of the random access response resource according to a predefined mapping.

7. The method of claim 6 wherein the predefined mapping is a predefined mapping between random access preamble indices and radio network temporary identifiers.

8. The method of claim 1 wherein the cellular communications network is a Long Term Evolution, LTE, network, and the random access response resource is a set of physical resource blocks.

9. The method of claim 8 further comprising receiving a random access response configuration from the cellular communications network, the random access response configuration indicating a number of physical resource blocks in the set of physical resource blocks.

10. The method of claim 1 wherein the random access response resource determined from the random access preamble index is valid for multiple subframes determined from the random access preamble index, and receiving the random access response on the random access response resource comprises receiving the random access response on the random access response resource over the multiple subframes.

11. The method of claim 10 wherein the random access response is repeated over the multiple subframes.

12. The method of claim 1 wherein determining, from the random access preamble index, one of the random access response resource and the channel to monitor for the transmission of the indication of the random access response resource comprises determining, from the random access preamble index and a cell index of a cell for which the wireless device is performing random access, the one of the random access response resource and the channel to monitor for the transmission of the indication of the random access response resource.

13. The method of claim 1 wherein the random access response is divided into multiple parts comprising a common part that is common for multiple random access responses to multiple wireless devices, and receiving the random access response on the random access response resource comprises receiving the common part of the random access response on the random access response resource.

14. The method of claim 1 wherein the wireless device is a reduced bandwidth device that receives only a portion of a system bandwidth of a downlink of the cellular communications network.

15. The method of claim 14 wherein the cellular communications network is a Long Term Evolution, LTE, network, and the wireless device does not receive a downlink control channel that spans the system bandwidth.

16. A reduced bandwidth wireless device enabled to perform random access to a cellular communications network, the wireless device comprising:
a transceiver module;
a processing module; and
a memory module storing instructions executable by the processing module whereby the wireless device is operative to:
transmit, via the transceiver module, a random access preamble on a physical random access channel;
determine, from a random access preamble index of the transmitted random access preamble, one of a random access response resource and a channel to monitor for a transmission of an indication of the random access response resource, wherein the random access response resource is determined from the random access preamble index according to a predefined mapping of random access preamble indices and random access response resources; and
receive, via the transceiver module, a random access response on the random access response resource, wherein the random access response resource determined from the random access preamble index is valid for a single subframe determined from the random access preamble index, and receiving the random access response on the random access response resource comprises receiving the random access response on the random access response resource in the single subframe.

17. The reduced bandwidth wireless device of claim 16 wherein the channel to monitor for the transmission of the indication of the random access response resource is determined from the random access preamble index.

18. The reduced bandwidth wireless device of claim 17 wherein the channel to monitor for the indication of the random access response resource is determined according to a predefined mapping.

19. The reduced bandwidth wireless device of claim 18 wherein the predefined mapping is a predefined mapping between random access preamble indices and radio network temporary identifiers.

20. The reduced bandwidth wireless device of claim 16 wherein the wireless device is a reduced bandwidth device that receives only a portion of a system bandwidth of a downlink of the cellular communications network.

21. A method of operation of a base station to perform random access to a cellular communications network, the method comprising:
detecting a random access preamble on a physical random access channel;
determining, from a random access preamble index of the transmitted random access preamble, one of a random access response resource and a channel to transmit an indication of the random access response resource, wherein determining the random access response resource comprises determining the random access response resource from the random access preamble according to a predefined mapping of random access preamble indices and random access response resources; and
transmitting a rand

Assignees

• Ericsson Telefon Ab L M
• Ericsson Telefon Ab L M

Inventors

• Eriksson Erik
• Bergman Johan

Classifications

• H04W74/0833 Primary

  Random access procedures, e.g. with 4-step access · CPC title

• H04W74/0838

  using contention-free random access [CFRA] · CPC title