Enhanced rach design for machine-type communications

• US 20120033613A1
• Filed: 08/03/2011
• Published: 02/09/2012
• Est. Priority Date: 08/04/2010
• Status: Abandoned Application

• Current Assignee: National Taiwan University (Government of The Republic of China), MediaTek, Inc.
• Original Assignee: National Taiwan University (Government of The Republic of China), MediaTek, Inc.
• Inventors: Lin, Guan-Yu, Wei, Hung-Yu, Chen, Yih-Shen, Hsu, Chia-Chun
• Application Number:
  US13/136,558
• Publication Number:
  US 20120033613A1
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 48/06 based on traffic conditions
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 74/085 collision avoidance
• CPC Class Codes: H04W 84/04 Large scale networks; Deep hierarchical networks

Abstract

An adaptive RACH operation is proposed for machine-type communications (MTC) in a 3GPP wireless network. The adaptive RACH operation is based on context information to reduce RACH collision probability, to control network overload, and to enhance system performance. The context information includes device related information and network related information. Device related information includes device type and service or application type. Network related information includes network load information and historical statistics information. Based on the context information, an MTC device adjusts various network access and RACH parameters by applying adaptive RACH operation in different levels. For example, in the application level and the network level, the MTC device adjusts its access probability or RACH backoff time for RACH access. In the radio access network (RAN) level, the MTC device adjusts its access probability or RACH backoff time, or transmits RACH preambles using adjusted RACH radio resources and preambles.

Claims

1. A method comprising:

performing radio access network (RAN) level access barring by a machine-to-machine (M2M) device in a wireless communication network, wherein the M2M device adaptively adjusts access probability by applying different barring parameters based on an access class (AC) of the M2M device; and

performing a random access channel (RACH) procedure with a base station after gaining access.

2. The method of claim 1, further comprising:

performing non-access stratum (NAS) level access distribution among other MTC devices in the network, wherein the NAS level access distribution is based on service type, an MTC server, or a device ID of the M2M device.

3. The method of claim 1, further comprising:

performing machine-type communications (MTC) application level access distribution based on a priority of an MTC application running on the MTC device.

4. The method of claim 1, wherein a first access barring factor is used for the M2M device while a second access barring factor is used for a human-to-human (H2H) device.

5. The method of claim 1, wherein a first retry timer is used for the M2M device while a second retry timer is used for a human-to-human (H2H) device.

6. A method, comprising:

applying a first backoff time by a machine-to-machine (M2M) device in a wireless communication network;

transmitting a random access channel (RACH) preamble to a base station after applying the first backoff time;

applying a second backoff time if the first RACH preamble detection is failed based on context information; and

re-transmitting the RACH preamble to the base station after applying the second backoff time.

7. The method of claim 6, wherein the M2M device has a built-in distribution for the first backoff time.

8. The method of claim 6, wherein the first backoff time is assigned in machine-type communications (MTC) application level or core network level.

9. The method of claim 6, wherein the first backoff time is assigned in RACH access level, and wherein the first backoff time is broadcasted through different radio network temporary identifiers (RNTI) or indicated by either reserved bits or a radio resource control (RRC) message.

10. The method of claim 6, wherein the RACH preamble is dedicated for machine-type communications.

11. The method of claim 6, wherein the RACH preamble is transmitted over subframes and resource blocks dedicated for machine-type communications.

12. The method of claim 6, wherein the second backoff time is contained in a backoff indicator transmitted from the base station via a random access response (RAR) message.

13. The method of claim 12, wherein the second backoff time is determined by the base station based at least in part on device-related context information including device type and application/service type.

14. The method of claim 6, wherein the second backoff time is computed by the M2M device based on network-related context information including load information and historical statistics.

15. The method of claim 6, wherein the M2M device waits for one or more subframes before re-transmitting the RACH preamble.

16. The method of claim 6, wherein the M2M device goes back to power saving mode and waits until the next discontinuous reception (DRX) cycle before re-transmitting the RACH preamble.

17. A method, comprising:

allocating a first random access channel (RACH) resource by a base station to be used by a plurality of machine-type communications (MTC) devices in a wireless communication network;

allocating a second RACH resource to be used by a plurality of human-to-human (H2H) devices; and

allocating a third RACH resource to be shared by the plurality of M2M devices and the plurality of H2H devices.

18. The method of claim 17, wherein the first, the second, and the third RACH resources are mutually exclusive.

19. The method of claim 17, wherein the first RACH resource is a subset of the second RACH resource.

20. The method of claim 17, wherein RACH resource includes RACH transmission time, RACH transmission frequency, and RACH preamble.

21. The method of claim 17, wherein the first, the second, and the third RACH resources are adaptively allocated based on load information.

22. The method of claim 17, wherein the first, the second, and the third RACH resources are adaptively allocated based on collision probability or retransmission count.

23. A method, comprising:

receiving machine-type communications (MTC) configuration transmitted from a base station by a MTC device in a wireless communication system;

receiving an MTC uplink grant transmitted from the base station; and

transmit MTC data in the MTC uplink grant resource region without radio resource control (RRC) connection establishment.

24. The method of claim 23, wherein multiple MTC devices under a cell share a common radio bearer configuration.