ENABLING DOWNLINK TRANSPARENT RELAY IN A WIRELESS COMMUNICATIONS NETWORK

• US 20110306291A1
• Filed: 08/12/2009
• Published: 12/15/2011
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Ma, Jianglei, Xu, Hua, Zhang, Hang, Zhu, Peiying, Tong, Wen
• Granted Patent: US 8,737,912 B2
• Time in Patent Office: Days
• US Class Current: 455/9
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

Methods and apparatus are described for enabling downlink transparent relay in a wireless communication network. In a wireless communications network, a base station and a mobile station may communicate with each other via a relay station, as needed. Transparent relay may allow for relay communication between a base station and a mobile station although the mobile station is unaware of the relay station. However, non-contiguous transmission of a relay station may lead to channel quality measurement and channel estimation degradation during downlink transparent relay. According to some aspects, a base station may schedule a mobile station to a transmission mode that utilizes dedicated pilot signals for downlink transparent relay, and a relay station may transmit data and dedicated pilot signals over the same channel resources as the base station. According to some aspects, the relay station may null common pilot signals transmitted by the base station.

Claims

1. A relay method in a wireless communication system comprising:

a relay station receiving data, dedicated pilot signals, and common pilot signals from a base station;

the relay station nulling the common pilot signals; and

the relay station transmitting the data and dedicated pilot signals to a mobile station.

2. The method of claim 1, further comprising the base station transmitting the data, the dedicated pilot signals and the common pilot signals to the mobile station, wherein

the base station and the relay station transmit the data and dedicated pilot signals over the same channel resources.

3. The method of claim 1, further comprising the mobile station measuring channel quality based on the common pilot signals received from the base station.

4. The method of claim 1, further comprising the mobile station performing channel estimation based on the dedicated pilot signals received from the base station and the relay station, wherein the mobile station only performs channel estimation during subframes which contain the dedicated pilot signals.

5. The method of claim 1, wherein the base station, the mobile station, and the relay station are each configured to operate utilizing a LTE standard.

6. The method of claim 5, further comprising the base station scheduling a LTE transmission mode to the mobile station, the LTE transmission mode utilizing dedicated pilot signals.

7. The method of claim 6, wherein the LTE transmission mode is LTE Transmission Mode 7.

8. The method of claim 5, wherein the relay station and the mobile station transmit the dedicated pilot signals over resource elements that are not occupied by the common pilot signals transmitted by the base station.

9. The method of claim 8, wherein the step of the relay station nulling the common pilot signals further comprises the relay station nulling the resource elements occupied by the common pilot signals transmitted by the base station.

10. The method of claim 1, wherein the relay method is part of a Hybrid Automatic Repeat reQuest (HARQ) process.

11. The method of claim 1, wherein the base station and the relay station each pre-code the data and the dedicated pilot signals using a pre-coding matrix.

12. The method of claim 1, wherein:

the base station selects a channel quality indicator (CQI) reporting mode for the mobile station, the CQI being based on the channel quality measurements;

the reporting mode selected by the base station is aperiodic reporting using the physical uplink shared channel; and

the reporting mode is signalled to the mobile station through radio resource control.

13. An apparatus in a relay station comprising:

a module for receiving data, dedicated pilot signals, and common pilot signals from a base station;

a module for nulling the common pilot signals; and

a module for transmitting the data and the dedicated pilot signals to a mobile station.

14. The apparatus of claim 13, wherein the relay station is configured to operate utilizing a LTE standard.

15. The apparatus of claim 14, wherein the module for transmitting is configured to transmit to a mobile station which is scheduled to a LTE transmission mode, the LTE transmission mode utilizing the dedicated pilot signals.

16. The apparatus of claim 15, wherein the LTE transmission mode is LTE Transmission Mode 7.

17. The apparatus of claim 14, wherein the module for transmitting is configured to transmit the dedicated pilot signals over resource elements that are not occupied by the common pilot signals transmitted by the base station, and

the module for nulling the common pilot signals is configured to null the resource elements occupied by the common pilot signals transmitted by the base station.

18. A wireless relay based communications network comprising:

a base station;

a relay station; and

a mobile station, wherein

the relay station receives data, dedicated pilot signals, and common pilot signals from the base station,

the relay station nulls the common pilot signals, and

the base station and the relay station transmit the data and dedicated pilot signals to the mobile station over the same channel resources.

19. The network of claim 18, wherein the mobile station measures channel quality based on the common pilot signals received from the base station,

the mobile station performs channel estimation based on the dedicated pilot signals received from the base station and the relay station, and

the mobile station only performs channel estimation during subframes which contain the dedicated pilot signals.

20. The network of claim 19, wherein, the base station, the mobile station, and the relay station are each configured to operate utilizing a LTE standard, and

the base station schedules a LTE transmission to the mobile station, the LTE transmission mode utilizing dedicated pilot signals.