Method for optimizing spatial modulation in a wireless link and network element thereto

• US 8,160,601 B2
• Filed: 06/21/2007
• Issued: 04/17/2012
• Est. Priority Date: 06/21/2007
• Status: Active Grant

• Current Assignee: Elektrobit Wireless Communications OY (Bittium Oyj)
• Original Assignee: Elektrobit Wireless Communications OY (Bittium Oyj)
• Inventors: Ylitalo, Juha, Veselinovic, Nenad
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): Chughtai, Sarwat
• Application Number:
  US11/766,245
• Publication Number:
  US 20080317014A1
• Time in Patent Office: 1,762 Days
• Field of Search: 370216-253, 370203-210, 370/394, 4554521-4522, 455453-455, 455423-425
• US Class Current: 455/452.2
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]

Abstract

The selection of the spatial mode together with modulation and encoding schemes based on channel condition measurements requested from MS forms a basis for selecting a best transmission data rate in a wireless link in every channel conditions. A method and network element comprising multiple-input multiple-output (MIMO) capable antenna technology allows the use of a best transmission data rate in the channel if selection of transmission mode has been made correctly. The thresholds for transmission mode selections are pre-determined and compared to instantaneous channel quality information. The practical MIMO solution based on correct selection procedure provides also continuous sufficient channel condition for terminal users when the user moves from LOS situation to NLOS situation.

Claims

1. A method for selecting a best transmission mode for frame between a base station and a mobile terminal in a wireless channel in every channel conditions, comprising

receiving at the base station as a response to a request to the mobile terminal at least one condition figure indicating instantaneous condition of a channel,

mapping at the base station the condition figure to a first threshold range, said first threshold range being limited with a first minimum threshold value and a first maximum threshold value and being predefined to correspond the condition figure,

selecting at the base station a comparison value to be within the first threshold range,

comparing at the base station the comparison value to at least one second threshold range being limited with a second minimum threshold value and a second maximum threshold value, wherein each of said second threshold ranges is stored in the base station and is pre-determined to correspond to a transmission mode of a best transmission data rate,

selecting at the base station the transmission mode corresponding to the second threshold range within which the comparison value belongs in order to transmit the frame forwards,

wherein the transmission mode comprises at least selection of one of multiple-input multiple-output mode, modulation and coding.

2. The method according to claim 1, wherein receiving the condition figure precedes performing a post detection CINR measurement at a mobile station and transmitting the condition figure indicating a predefined threshold range within which a result of the CINR measurement performed belongs.

3. The method according to claim 1, wherein comparing the comparison value precedes verifying a transmission data rate and a post detection CINR measurement for each transmission mode in a known channel and storing the at least one second threshold range that correlates to the transmission mode providing a best transmission data rate according to verifying.

4. The method according to claim 3, wherein the transmission mode comprises one of the following modes:

vertical encoding with same modulation for the channel, vertical encoding with same modulations for layers of the channel, vertical encoding with different modulations possible for layers of the channel and horizontal encoding.

5. The method according to claim 1, wherein the at least one second threshold range is stored at the base station in a form of one dimensional table or one dimensional projection values derived from n dimensional tables, n representing a number of layers of the channel.

6. The method according to claim 5, wherein the condition figure represents a single post detection CINR measurements of the channel.

7. The method according to claim 5, wherein the condition figure represents a combination of post detection CINR measurements of different layers of the channel.

8. The method according to claim 5, wherein the condition figure represents a post detection CINR measurement of a layer of the channel.

9. The method according to claim 1, wherein the at least one second threshold range is stored at the base station in a form of n dimensional tables, n representing a number of layers of the channel.

10. The method according to claim 9, wherein the condition figure represents a post detection CINR measurement of a layer of the channel.

11. Method according to claim 1, wherein the comparison value equals or is close to the first minimum threshold value.

12. The method according to 1, wherein the request for the condition figure comprises a parameter that allows BS to receive the condition figure indicating instantaneous condition of the channel.

13. The method according to claim 1, wherein the step of selecting the transmission mode further comprises selecting a number of antennas or antenna groups and selecting antenna precoding.

14. A network element in a base station, comprising

a receiver comprising at least one receiving antenna arranged to receive as a response to a request at least one condition figure indicating instantaneous condition of a channel,

a controller arranged to map the condition figure to a first threshold range, said first threshold range being limited with a first minimum threshold value and a first maximum threshold value and being predefined to correspond the condition figure,

a means for selecting a comparison value arranged to be within the first threshold range,

a memory arranged to store at least one second threshold range being limited with a second minimum threshold value and a second maximum threshold value, the second threshold range being pre-determined to correspond to a transmission mode of a best transmission data rate,

a decision making block arranged to compare the comparison value to at least one second threshold range,

the decision making block arranged to select the transmission mode corresponding to the second threshold range within which the comparison value belongs, wherein the transmission mode comprises at least selection of one of multiple-input multiple-output mode, modulation and coding, and

a transmitter comprising at least one transmitting antenna arranged to transmit the frame forwards.

15. The network element according to claim 14, wherein receiver is arranged receive the condition figure from a mobile station that performs a post detection CINR measurement and transmits the condition figure indicating a predefined threshold range within which a result of the CINR measurement performed belongs.

16. The network element according to claim 14, wherein the memory is arranged to store the at least one second threshold range that correlates to the transmission mode providing a best transmission data rate as a result of verifying a transmission data rate and a post detection CINR measurement for each transmission mode in a known channel.

17. The network element according to claim 16, wherein the transmission mode comprises one of the following modes:

vertical encoding with same modulation for each antenna, vertical encoding with different modulations possible for each antenna and horizontal encoding.

18. The network element according to claim 14, wherein the memory is arranged to store the at least one second threshold range in a form of one dimensional table or one dimensional projection values derived from n dimensional tables, n representing a number of layers of the channel.

19. The network element according to claim 18, wherein the condition figure represents a single post detection CINR measurement of the channel.

20. The network element according to claim 18, wherein the network element further comprises a means for combining arranged to combine post detection CINR measurements of different layers of the channel received by the receiver to represent the condition figure.

21. The network element according to claim 18, wherein the condition figure represents a post detection CINR measurement of a layer of the channel.

22. The network element according to claim 14, wherein the memory is arranged to store the at least one second threshold range in a form of n dimensional tables, n representing a number of layers of the channel.

23. The network element according to claim 22, wherein the receiver is arranged to receive the condition figure representing a post detection CINR measurement of a layer of the channel.

24. The network element according to claim 14, wherein the comparison value equals or is close to the first minimum threshold value.

25. The network element according to 14, wherein the network element further comprises a transmitter arranged to send to the mobile station the request for the condition figure comprises a parameter that allows BS to receive the condition figure indicating instantaneous condition of the channel.

26. The network element according to 14, wherein the receiver and the transmitter comprises at least one dual-polarized antenna arranged to function in a multiple-input multi-output transmission modes.

27. The network element according to claim 14, wherein the decision making block is further arranged to select a number of transmitting antennas from multiple antennas or a number of transmitting antenna groups from multiple antenna groups and antenna precoding.

28. A computer-readable medium having computer-executable components, comprising

receiving as a response to a request at least one condition figure indicating instantaneous condition of a channel,

mapping the condition figure to a first threshold range, said first threshold range being limited with a first minimum threshold value and a first maximum threshold value and being predefined to correspond the condition figure,

selecting a comparison value arranged to be within the first threshold range,

storing at least one second threshold range being limited with a second minimum threshold value and a second maximum threshold value, the second threshold range being pre-determined to correspond to a transmission mode of a best transmission data rate,

comparing the comparison value to at least one second threshold range, and

selecting the transmission mode corresponding to the second threshold range within which the comparison value belongs,

wherein the transmission mode comprises at least selection of one of multiple-input multiple-output mode, modulation and coding.