Method of controlling data transmission in a wireless relay system, and the relay system implementing the method

• US 20080045212A1
• Filed: 12/14/2006
• Published: 02/21/2008
• Est. Priority Date: 08/21/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nam, Seung Hoon, Kim, Eung Sun, Kim, Young-Doo, Ahn, Chang Wook
• Granted Patent: US 8,150,409 B2
• Time in Patent Office: Days
• US Class Current: 455/435.1
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0668 Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point

Abstract

A data transmission method in a wireless relay system, and a method of selecting an optimal transmission mode based on a channel capacity of an individual link that is measured by a mobile station. The data transmission method includes: transmitting a first ratio of first partial data of the data from a base station to a mobile station; transmitting a second ratio of second partial data of the data from the base station to a first relay station; and forwarding the second partial data from the first relay station to the mobile station, wherein the first ratio or the second ratio is determined based on any one of a channel capacity of a first link between the base station and the mobile station, and a channel capacity of a second link between the first relay station and the mobile station.

Claims

1. A method of transmitting data via a downlink channel in a wireless relay system, the method comprising:

transmitting a first ratio of first partial data of the data from a base station to a mobile station;

transmitting a second ratio of second partial data of the data from the base station to a first relay station; and

forwarding the second partial data from the first relay station to the mobile station,

wherein the first ratio or the second ratio is determined based on any one of a channel capacity of a first link between the base station and the mobile station, and a channel capacity of a second link between the first relay station and the mobile station.

2. The method of claim 1, wherein the transmitting of the first partial data and the forwarding of the second partial data are simultaneously performed after transmitting the second partial data.

3. The method of claim 1, further comprising:

receiving at least one of the channel capacity of the first link and the channel capacity of the second link, wherein said channel capacity of the first link and said channel capacity of the second link are measured by the mobile station.

4. The method of claim 3, wherein the base station determines the first ratio and the second ratio based on at least one of the channel capacity of the first link and the channel capacity of the second link.

5. The method of claim 1, further comprising:

measuring the channel capacity of the first link and the channel capacity of the second link by the mobile station;

determining the first ratio and the second ratio by the mobile station, based on at least one of the channel capacity of the first link and the channel capacity of the second link; and

transmitting the determined first ratio and the determined second ratio to the base station or the first relay station.

6. The method of claim 1, wherein the first ratio α

₁ and the second ratio α

₂ are determined according to the following equations,

7. The method of claim 1, wherein the forwarding comprises:

decoding the received second partial data from the base station; and

encoding the decoded second partial data at a predetermined code rate to forward to the mobile station.

8. The method of claim 7, wherein the code rate is determined by the mobile station, based on at least one of the channel capacity of the first link and the channel capacity of the second link.

9. The method of claim 1, further comprising:

receiving and forwarding of the data by a second relay station,

wherein the forwarding of the second partial data comprises;

forwarding the second partial data, received from the base station, from the first relay station to the second relay station; and

forwarding the second partial data, received from the first relay station, from the second relay station to the mobile station.

10. A method of transmitting data via a downlink channel in a wireless relay system, the method comprising:

directly transmitting first partial data from a base station to a mobile station; and

transmitting second partial data from the base station to the mobile station via at least one relay station,

wherein the first partial data and the second partial data are contained in a total of the data transmitted from the base station and are different from each other.

11. A method of controlling a data transmission in a wireless relay system, the method comprising:

estimating channels of a plurality of wireless links that respectively connect a base station, a relay station, and a mobile station to each other;

selecting any one of a plurality of transmission modes by the mobile station, based on a channel estimation value; and

transmitting information about the selected transmission mode to the base station and the relay station,

wherein the plurality of transmission modes comprises at least one of;

a first mode which directly transmits total data from the base station to the mobile station;

a second mode which directly transmits the total data from the base station to the mobile station, and transmits the total data from the base station to the mobile station via the relay station; and

a third mode which directly transmits a certain portion of the total data from the base station to the mobile station, and transmits remaining data from the base station to the mobile station via the relay station, and

wherein the base station and the relay station transmit the data according to the selected transmission mode.

12. The method of claim 11, wherein the estimating comprises:

estimating a channel of a first link between the base station and the mobile station, by the mobile station;

estimating a channel of a second link between the relay station and the mobile station, by the mobile station; and

receiving a second channel estimation value of a third link between the base station and the relay station, by the mobile station.

13. The method of claim 11, wherein the selecting comprises:

calculating a channel capacity associated with the plurality of wireless links, based on the channel estimation value;

calculating an estimated transmission time of the data in each of the plurality of transmission modes, based on the calculated channel capacity; and

selecting a transmission mode with a minimum estimated transmission time from the plurality of transmission modes.

14. The method of claim 13, wherein the channel capacity comprises an open-loop capacity from the base station to the mobile station when the transmission mode is the first mode.

15. The method of claim 13, wherein the channel capacity comprises a closed loop capacity from the base station to the relay station, and a diversity capacity from the base station and the relay station to the mobile station, when the transmission mode is the second mode.

16. The method of claim 13, wherein the channel capacity comprises a closed loop capacity from the base station to the relay station, an open-loop capacity from the base station to the mobile station, and an open-loop capacity from the relay station to the mobile station, when the transmission mode is the third mode.

17. The method of claim 13, wherein the estimated transmission time T₁ of the first mode is calculated according to the following equation,

T₁=B/C_bm

where B designates a number of bits of transmitted data, and C_bm designates an open-loop capacity from the base station to the mobile station.

18. The method of claim 13, wherein the estimated transmission time T₂ of the second mode is calculated according to the following equation,

T₂=B/C_br+B/C_div

where B designates a number of bits of transmitted data, C_br designates a closed loop capacity from the base station to the relay station, and, C_div designates a diversity capacity from the base station and the relay station to the mobile station.

19. The method of claim 13, wherein the estimated transmission time T₃ of the third mode is calculated according to an equation,

20. The method of claim 11, further comprising:

determining a code rate of each of the plurality of wireless links by the mobile station, based on the channel estimation value; and

transmitting the determined code rate to each of the base station and the relay station,

wherein the base station and the relay station encode the data according to the determined code rate and transmits the encoded data.

21. The method of claim 11, wherein the third mode comprises:

transmitting first partial data from the base station to the relay station in a first time slot;

forwarding the first partial data from the relay station to the mobile station in a second time slot; and

directly transmitting second partial data from the base station to the mobile station in the second time slot.

22. The method of claim 21, wherein a plurality of relays stations are provided, and the transmitting of the first partial data simultaneously transmits third partial data and fourth partial data that are contained in the first partial data.

23. A method of controlling a data transmission in a wireless relay system, the method comprising:

selecting any one of a plurality of transmission modes by a base station, based on a comparative location of a relay station and a mobile station; and

transmitting information about the selected transmission mode to the base station and the relay station, so that the base station and the relay station transmit data according to the selected transmission mode,

wherein the plurality of transmission modes comprises at least one of;

a first mode which directly transmits total data from the base station to the mobile station;

a second mode which simultaneously transmits the total data from the base station to the mobile station and to the relay station; and

a third mode which directly transmits a certain portion of the total data from the base station to the mobile station, and transmits remaining data from the base station to the mobile station via the relay station.

24. A method of controlling a data transmission in a wireless relay system, the method comprising:

estimating channels of a plurality of wireless links that respectively connect a base station, a relay station, and a mobile station to each other;

determining a modulation and coding scheme (MCS) level of each of the plurality of wireless links by the mobile station, based on the channel estimation value; and

transmitting the determined MCS level to the base station and the relay station,

wherein the base station and the relay station transmit data according to the determined MCS level.

25. A wireless relay system comprising:

a base station which directly transmits first partial data of total data to a mobile station, and transmits second partial data of the total data to the mobile station via a relay station,

wherein the relay station forwards the second partial data, received from the base station, to the mobile station.

26. The wireless relay system of claim 25, wherein the relay station decodes the second partial data, and encodes the decoded second partial data at a predetermined code rate to forward to the mobile station.

27. The wireless relay system of claim 26, wherein the code rate is determined by the mobile station, and is based on at least one channel estimation value of the plurality of wireless links that respectively connect the base station, the relay station, and the mobile station to each other.

28. A wireless relay system comprising a base station, a relay station, and a mobile station in each of a plurality of cells, wherein:

the base station directly transmits first partial data of total data to the mobile station, and transmits second partial data of the total data to the mobile station via the relay station, and

the mobile station simultaneously receives the first partial data from the base station and the second partial data from the relay station.

29. The wireless relay system of claim 28, wherein the mobile station determines a comparative ratio of the first partial data to the second partial data based on a channel capacity of a first link between the base station and the mobile station and a channel capacity of a second link between the relay station and the mobile station.

30. The wireless relay system of claim 28, wherein the relay station decodes the second partial data, and encodes the decoded second partial data at a predetermined code rate to forward to the mobile station.

31. The wireless relay system of claim 30, wherein the code rate is determined by the mobile station, and is based on at least one channel estimation value of the plurality of wireless links that respectively connect the base station, the relay station, and the mobile station to each other.

32. A wireless relay system comprising a base station, at least one relay station, and a mobile station in each of a plurality of cells, wherein:

the mobile station measures a channel capacity of a plurality of wireless links that respectively connect the base station, the relay station, and the mobile station to each other, and selects any one of a plurality of transmission modes, based on the measured channel capacity, and the base station and the relay station transmit data to the mobile station according to the selected transmission mode, and

the plurality of transmission modes comprises at least one of;

a first mode which directly transmits total data from the base station to the mobile station;

a second mode which directly transmits the total data from the base station to the mobile station, and transmits the total data from the base station to the mobile station via the at least one relay station; and

a third mode which directly transmits a certain portion of the total data from the base station to the mobile station, and transmits remaining data from the base station to the mobile station via the at least one relay station.

33. The wireless relay system of claim 32, wherein the mobile station comprises two antennas, and each of the base station and the relay station comprises a single antenna, and the plurality of transmission modes comprises the first mode, the second mode, and the third mode.

34. The wireless relay system of claim 32, wherein each of the base station and the relay station comprises four antennas, and the mobile station comprises a single antenna, and the plurality of transmission modes comprises the first mode and the second mode.

35. The wireless relay system of claim 32, wherein each of the base station and the relay station comprises four antennas, and the mobile station comprises two antennas, and the plurality of transmission modes comprises the first mode, the second mode, and the third mode.