Transmit spatial diversity for cellular single frequency networks

• US 20060280262A1
• Filed: 06/08/2006
• Published: 12/14/2006
• Est. Priority Date: 06/14/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Malladi, Durga Prasad
• Granted Patent: US 8,059,608 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 27/3488 Multiresolution systems

Abstract

Multiple-In Multiple-Out (MIMO) techniques are used to increase spectral efficiency of a cellular single frequency network. In some embodiments with single transmit antenna per cell, multiple data streams are transmitted from multiple cells, one data stream per set of transmit antennae. The mapping of streams to antenna sets is permuted in time. In this way, user equipment devices (UEs) at cell edges benefit from MIMO, and UEs near cell centers benefit from high carrier-to-interference (C/I) ratio of the signal. In some embodiments, each stream is concurrently transmitted on base layer of a hierarchically modulated signal from one set, and on enhancement layer of a hierarchically modulated signal from another set. The mapping of sets to streams is permuted in time. The UEs at cell edges benefit from MIMO, and the UEs near cell centers benefit from the high C/I to decode both streams from the base and enhancement layers.

Claims

1. A method of transmitting data from a plurality of sectors in a cellular communication system, the method comprising:

assigning at least one transmit antenna from each sector of the plurality of sectors to a transmit antenna set of a plurality of L transmit antenna sets, L being an integer greater than 1, each transmit antenna set of the plurality of L transmit antenna sets comprising at least one transmit antenna of the cellular communication system;

arranging the data into a plurality of L data streams;

assigning, for at least one first period, each data stream of the plurality of L data streams to a different transmit antenna set of the L transmit antenna sets, resulting in a first distribution of data streams among transmit antenna sets;

for said each transmit antenna set of the plurality of L transmit antenna sets, modulating, during the at least one first period, a carrier of a first frequency with the data stream assigned to said each transmit antenna set during the at least one first period; and

transmitting to a plurality of receivers during the at least one first period the carrier through the transmit antennae of the plurality of L transmit antenna sets so that transmit antennae of said each transmit antenna set transmit during the at least one first period the data stream assigned to said each transmit antenna set for the at least one first period.

2. The method of claim 1, wherein the plurality of L antenna sets comprises a first transmit antenna and a second transmit antenna, the first transmit antenna being in a first sector of the cellular communication system, the first antenna being the only transmit antenna of the cellular communication system in the first sector configured to transmit using the first frequency.

3. The method of claim 2, wherein the second antenna is in a second sector of the cellular communication system, the second antenna being the only transmit antenna of the cellular communication system in the second sector configured to transmit using the first frequency.

4. The method of claim 1, further comprising:

assigning, for at least one second period, said each data stream to a different transmit antenna set of the L transmit antenna sets, resulting in a second distribution of data streams among transmit antenna sets, the second distribution being different from the first distribution;

for said each transmit antenna set of the plurality of L transmit antenna sets, modulating, during the at least one second period, the carrier with the data stream assigned to said each transmit antenna set during the at least one second period; and

transmitting to a plurality of receivers during the at least one second period the carrier through the transmit antennae of the plurality of L transmit antenna sets so that transmit antennae of said each transmit antenna set transmit during the at least one second period the data stream assigned to said each transmit antenna set for the at least one second period.

5. The method of claim 4, wherein:

L is equal to two;

the at least one first period comprises a plurality of first periods;

the at least one second period comprises a plurality of second periods; and

during a first time duration the first periods of the plurality of first periods are interleaved with the second periods of the plurality of second periods.

6. The method of claim 1, wherein:

the plurality of L transmit antenna sets comprises a first transmit antenna set; and

the first transmit antenna set comprises a first antenna from a first sector and a second antenna from a second sector.

7. A radio network controller for a cellular communication system comprising a plurality of sectors, each sector comprising at least one transmit antenna and at least one base transceiver station, wherein the at least one radio network controller is configured to perform operations comprising:

assigning at least one transmit antenna from each sector of the plurality of sectors to a transmit antenna set of a plurality of L transmit antenna sets, L being an integer greater than 1, each transmit antenna set of the plurality of L transmit antenna sets comprising at least one transmit antenna of the cellular communication system;

arranging data into a plurality of L data streams;

assigning, for at least one first period, each data stream of the plurality of L data streams to a different transmit antenna set of the L transmit antenna sets, resulting in a first distribution of data streams among transmit antenna sets;

for said each transmit antenna set of the plurality of L transmit antenna sets, causing the plurality of sectors to modulate, during the at least one first period, a carrier of a first frequency with the data stream assigned to said each transmit antenna set during the at least one first period; and

causing the plurality of sectors to transmit to a plurality of receivers during the at least one first period the carrier through the transmit antennae of the plurality of L transmit antenna sets so that transmit antennae of said each transmit antenna set transmit during the at least one first period the data stream assigned to said each transmit antenna set for the at least one first period.

8. The radio network controller of claim 7, wherein the plurality of L antenna sets comprises a first transmit antenna and a second transmit antenna, the first transmit antenna being in a first sector of the cellular communication system, the first antenna being the only transmit antenna of the cellular communication system in the first sector configured to transmit using the first frequency.

9. The radio network controller of claim 8, wherein the second antenna is in a second sector of the cellular communication system, the second antenna being the only transmit antenna of the cellular communication system in the second sector configured to transmit using the first frequency.

10. The radio network controller of claim 7, further configured to perform operations comprising:

assigning, for at least one second period, said each data stream to a different transmit antenna set of the L transmit antenna sets, resulting in a second distribution of data streams among transmit antenna sets, the second distribution being different from the first distribution;

for said each transmit antenna set of the plurality of L transmit antenna sets, causing the plurality of sectors to modulate, during the at least one second period, the carrier with the data stream assigned to said each transmit antenna set during the at least one second period; and

causing the plurality of sectors to transmit to a plurality of receivers during the at least one second period the carrier through the transmit antennae of the plurality of L transmit antenna sets so that transmit antennae of said each transmit antenna set transmit during the at least one second period the data stream assigned to said each transmit antenna set for the at least one second period.

11. A machine-readable medium comprising instructions, the instructions, when executed by at least one processor of a radio network controller for a cellular communication system comprising a plurality of sectors, each sector comprising at least one transmit antenna, configure the radio network controller to perform operations comprising:

assigning at least one transmit antenna from each sector of the plurality of sectors to a transmit antenna set of a plurality of L transmit antenna sets, L being an integer greater than 1, each transmit antenna set of the plurality of L transmit antenna sets comprising at least one transmit antenna of the cellular communication system;

arranging data into a plurality of L data streams;

assigning, for at least one first period, each data stream of the plurality of L data streams to a different transmit antenna set of the L transmit antenna sets, resulting in a first distribution of data streams among transmit antenna sets;

for said each transmit antenna set of the plurality of L transmit antenna sets, causing the plurality of sectors to modulate, during the at least one first period, a carrier of a first frequency with the data stream assigned to said each transmit antenna set during the at least one first period; and

causing the plurality of sectors to transmit to a plurality of receivers during the at least one first period the carrier through the transmit antennae of the plurality of L transmit antenna sets so that transmit antennae of said each transmit antenna set transmit during the at least one first period the data stream assigned to said each transmit antenna set for the at least one first period.

12. A method of transmitting data from a plurality of sectors in a cellular communication system, the method comprising:

assigning at least one transmit antenna of each sector of the plurality of sectors into a first transmit antenna set or a second transmit antenna set, each antenna set of the first and second transmit antenna sets comprising at least one transmit antenna;

arranging the data into a first data stream and a second data stream;

hierarchically modulating a carrier of a given frequency to obtain a first signal having a first base layer and a first enhancement layer;

hierarchically modulating the carrier to obtain a second signal having a second base layer and a second enhancement layer;

transmitting the first signal through each transmit antenna in the first transmit antenna set; and

transmitting the second signal through each antenna in the second transmit antenna set;

wherein the steps of hierarchically modulating are performed so that the first base layer carries information of the first data stream, the first enhancement layer carries information of the second data stream, the second base layer carries information of the second data stream, and the second enhancement layer carries information of the first data stream.

13. The method of claim 12, wherein the step of transmitting the one or more first hierarchically modulated carriers comprises broadcasting or multicasting.

14. A radio network controller for a cellular communication system comprising a plurality of sectors, each sector comprising at least one transmit antenna, wherein the radio network controller is configured to perform operations comprising:

assigning the at least one transmit antenna of each sector of the plurality of sectors into a first transmit antenna set or a second transmit antenna set, each antenna set of the first and second transmit antenna sets comprising at least one transmit antenna;

arranging data into a first data stream and a second data stream;

causing hierarchical modulation of a carrier of a given frequency to obtain a first signal having a first base layer and a first enhancement layer;

causing hierarchical modulation of the carrier to obtain a second signal having a second base layer and a second enhancement layer;

causing transmission of the first signal through each transmit antenna in the first transmit antenna set; and

causing transmission of the second signal through each transmit antenna the second transmit antenna set;

wherein the first base layer carries information of the first data stream, the first enhancement layer carries information of the second data stream, the second base layer carries information of the second data stream, and the second enhancement layer carries information of the first data stream.

15. A machine-readable medium comprising instructions, the instructions, when executed by at least one processor of a radio network controller for a cellular communication system comprising a plurality of sectors, each sector comprising at least one transmit antenna, configure the radio network controller to perform operations comprising:

assigning the at least one transmit antenna of each sector of the plurality of sectors into a first transmit antenna set or a second transmit antenna set, each antenna set of the first and second transmit antenna sets comprising at least one transmit antenna;

arranging data into a first data stream and a second data stream;

causing hierarchical modulation of a carrier of a given frequency to obtain a first signal having a first base layer and a first enhancement layer;

causing hierarchical modulation of the carrier to obtain a second signal having a second base layer and a second enhancement layer;

causing transmission of the first signal through each transmit antenna in the first transmit antenna set; and

causing transmission of the second signal through each transmit antenna the second transmit antenna set;

wherein the first base layer carries information of the first data stream, the first enhancement layer carries information of the second data stream, the second base layer carries information of the second data stream, and the second enhancement layer carries information of the first data stream.

16. A method of transmitting data from a plurality of sectors in a cellular communication system, each of the sectors comprising at least one transmit antenna, the method comprising:

arranging the data into a plurality of data streams;

modulating a carrier of a given frequency with the plurality of data streams to obtain a first signal and a second signal for broadcasting the data from the plurality of sectors using a multiple in multiple out (MIMO) spatial diversity technique;

transmitting the first signal from each sector of a first set of sectors of the cellular communication system; and

transmitting the second signal from each sector of a second set of sectors of the cellular communication system.

17. The method of claim 16, wherein the step of modulating comprises time division multiplexing the streams with respect to the first and second sector sets of the cellular communication system.

18. The method of claim 16, wherein the step of modulating comprises hierarchically modulating.

19. A radio network controller of a cellular radio network comprising a plurality of cells, each cell comprising at least one transmit antenna, wherein the at least one radio network controller is configured to perform operations comprising:

arranging data into a plurality of data streams;

modulating a carrier of a given frequency with the plurality of data streams to obtain a first signal and a second signal for broadcasting the data from the plurality of cells using a multiple in multiple out (MIMO) spatial diversity technique;

causing the plurality of cells to transmit the first signal from each cell of a first set of cells of the cellular communication system; and

causing the plurality of cells to transmit the second signal from each cell of a second set of cells of the cellular communication system.

20. A machine-readable medium comprising instructions, the instructions, when executed by at least one processor of a radio network controller for cellular radio network comprising a plurality of cells, each cell comprising at least one transmit antenna, configure the radio network controller to perform operations comprising:

arranging data into a plurality of data streams;

causing the plurality of cells to modulate a carrier of a given frequency with the plurality of data streams to obtain a first signal and a second signal for broadcasting the data from the plurality of cells using a multiple in multiple out (MIMO) spatial diversity technique;

causing the plurality of cells to transmit the first signal from each cell of a first set of cells of the cellular communication system; and

causing the plurality of cells to transmit the second signal from each cell of a second set of cells of the cellular communication system.

21. A method of receiving data sent from a cellular communication system, the method comprising:

receiving at a first antenna a first signal during one or more first time periods, the first signal being carried on a first frequency, the first signal comprising a first data stream transmitted through a first physical channel and a second data stream transmitted through a second physical channel, the first data stream comprising first data during the one or more first time periods, the second data stream comprising second data during the one or more first time periods;

receiving at a second antenna a second signal during the one or more first time periods, the second signal being carried on the first frequency, the second signal comprising the first data stream transmitted through a third physical channel and the second data stream transmitted through a fourth physical channel;

estimating the first physical channel to obtain one or more first channel estimates;

estimating the second physical channel to obtain one or more second channel estimates;

estimating the third physical channel to obtain one or more third channel estimates;

estimating the fourth physical channel to obtain one or more fourth channel estimates; and

separating the first and second data streams from at least one of the first signal and the second signal using at least some of the one or more first, second, third, and fourth channel estimates, resulting in first separated data stream and second separated stream of the one or more first time periods.

22. The method of claim 21, further comprising:

first attempting to decode the first and the second data from the first and second separated data streams of the one or more first time periods.

23. The method of claim 22, wherein, if the step of first attempting to decode is not successful, the method further comprises:

receiving at the first antenna the first signal during one or more second time periods, the first signal comprising the second data stream transmitted through the first physical channel and the first data stream transmitted through the second physical channel, the first data stream comprising the first data during the one or more second time periods, the second data stream comprising the second data during the one or more second time periods;

receiving at the second antenna the second signal during the one or more second time periods, the second signal comprising the second data stream transmitted through the third physical channel and the first data stream transmitted through the fourth physical channel;

separating the first and second data streams from at least one of the first signal and the second signal using at least some of the one or more first, second, third, and fourth channel estimates, resulting in first separated data stream and second separated data stream of the one or more second time periods; and

second attempting to decode the first and the second data from the first and second separated data streams of the one or more first and second time periods.

24. The method of claim 21, wherein the step of receiving at the first antenna the first signal comprises receiving on a common channel.

25. The method of claim 21, wherein the step of receiving at the first antenna the first signal comprises receiving a broadcast or multicast transmission.

26. A wireless user equipment device for communicating with a base transceiver station of a cellular communication system, the wireless user equipment device comprising:

a first antenna and a second antenna;

a receiver coupled to the first and second antennae;

a memory storing program code; and

a processor coupled to the receiver and to the memory;

wherein;

the receiver is configured to;

receive at the first antenna a first signal during one or more first time periods, the first signal being carried on a first frequency, the first signal comprising a first data stream transmitted through a first physical channel and a second data stream transmitted through a second physical channel, the first data stream comprising first data during the one or more first time periods, the second data stream comprising second data during the one or more first time periods, and

receive at the second antenna a second signal during the one or more first time periods, the second signal being carried on the first frequency, the second signal comprising the first data stream transmitted through a third physical channel and the second data stream transmitted through a fourth physical channel; and

the processor is configured to perform operations comprising;

estimating the first physical channel to obtain one or more first channel estimates,

estimating the second physical channel to obtain one or more second channel estimates,

estimating the third physical channel to obtain one or more third channel estimates,

estimating the fourth physical channel to obtain one or more fourth channel estimates, and

separating the first and second data streams from at least one of the first signal and the second signal using at least some of the one or more first, second, third, and fourth channel estimates, resulting in first separated data stream and second separated stream of the one or more first time periods.

27. The wireless user equipment device of claim 26, wherein the processor is further configured to first attempt to decode the first and the second data from the first and second separated data streams of the one or more first time periods.

28. The wireless user equipment device of claim 27, wherein:

the receiver is further configured to;

receive at the first antenna the first signal during one or more second time periods, the first signal comprising the second data stream transmitted through the first physical channel and the first data stream transmitted through the second physical channel, the first data stream comprising the first data during the one or more second time periods, the second data stream comprising the second data during the one or more second time periods, and

receive at the second antenna the second signal during the one or more second time periods, the second signal comprising the second data stream transmitted through the third physical channel and the first data stream transmitted through the fourth physical channel; and

the processor is further configured, if the first attempting to decode is not successful, to perform operations comprising;

separating the first and second data streams from at least one of the first signal and the second signal using at least some of the one or more first, second, third, and fourth channel estimates, resulting in first separated data stream and second separated data stream of the one or more second time periods, and

second attempting to decode the first and the second data from the first and second separated data streams of the one or more first and second time periods.

29. A machine-readable medium comprising instructions, the instructions, when executed by at least one processor of a wireless user equipment device for communicating with a cellular communication system, cause the wireless user equipment device to perform operations comprising:

receiving from the cellular communication system at a first antenna a first signal during one or more first time periods, the first signal being carried on a first frequency, the first signal comprising a first data stream transmitted through a first physical channel and a second data stream transmitted through a second physical channel, the first data stream comprising first data during the one or more first time periods, the second data stream comprising second data during the one or more first time periods;

receiving from the cellular communication system at a second antenna a second signal during the one or more first time periods, the second signal being carried on the first frequency, the second signal comprising the first data stream transmitted through a third physical channel and the second data stream transmitted through a fourth physical channel;

estimating the first physical channel to obtain one or more first channel estimates;

estimating the second physical channel to obtain one or more second channel estimates;

estimating the third.;

physical channel to obtain one or more third channel estimates;

estimating the fourth physical channel to obtain one or more fourth channel estimates; and

separating the first and second data streams from at least one of the first signal and the second signal using at least some of the one or more first, second, third, and fourth channel estimates, resulting in first separated data stream and second separated stream of the one or more first time periods.

30. A method of receiving data sent from a cellular communication system, the method comprising:

receiving at a first antenna a first signal, the first signal comprising a first signal component transmitted through a first physical channel and a second signal component transmitted through a second physical channel, the first signal component comprising a first base layer carrying a first data stream and a first enhancement layer carrying a second data stream, the second signal component comprising a second base layer carrying the second data stream and a second enhancement layer carrying the first data stream;

receiving at a second antenna a second signal, the second signal comprising a third signal component transmitted through a third physical channel and a fourth signal component transmitted through a fourth physical channel, the third signal component comprising a third base layer carrying the first data stream and a third enhancement layer carrying the second data stream, the fourth signal component comprising a fourth base layer carrying the second data stream and a fourth enhancement layer carrying the first data stream;

estimating the first, second, third, and fourth physical channels to obtain one or more channel estimates;

separating the first and second signal components using the one or more channel estimates;

decoding the first data stream from the first base layer after the step of separating; and

decoding the second data stream from at least one layer selected from the first enhancement layer and the second base layer, after the step of separating;

wherein the first, second, third, and fourth signal components are hierarchically modulated using the same carrier frequency.

31. The method of claim 30, wherein the step of decoding the second data stream comprises decoding the second data stream from both the first enhancement layer and the second base layer.

32. The method of claim 30, wherein the step of receiving at the first antenna comprises receiving on a common channel.

33. The method of claim 30, wherein the step of receiving at the first antenna comprises receiving a broadcast or a multicast.

34. A wireless user equipment device for communicating with a base transceiver station of a radio network, the wireless user equipment device comprising:

a first antenna and a second antenna;

a receiver;

a memory storing program code; and

a processor coupled to the receiver and to the memory;

wherein;

the receiver is configured to;

receive at the first antenna a first signal, the first signal comprising a first signal component transmitted through a first physical channel and a second signal component transmitted through a second physical channel, the first signal component comprising a first base layer carrying a first data stream and a first enhancement layer carrying a second data stream, the second signal component comprising a second base layer carrying the second data stream and a second enhancement layer carrying the first data stream, and

receive at the second antenna a second signal, the second signal comprising a third signal component transmitted through a third physical channel and a fourth signal component transmitted through a fourth physical channel, the third signal component comprising a third base layer carrying the first data stream and a third enhancement layer carrying the second data stream, the fourth signal component comprising a fourth base layer carrying the second data stream and a fourth enhancement layer carrying the first data stream;

the processor is configured to;

estimate the first, second, third, and fourth physical channels to obtain one or more channel estimates,

separate the first and second signal components using the one or more channel estimates,

after separating, decode the first data stream from the first base layer, and

after separating, decode the second data stream from at least one layer selected from the first enhancement layer and the second base layer; and

the first, second, third, and fourth signal components are hierarchically modulated using the same carrier frequency.

35. A machine-readable medium comprising instructions, the instructions, when executed by at least one processor of a wireless user equipment device, cause the wireless user equipment device to perform operations comprising:

receiving at a first antenna a first signal, the first signal comprising a first signal component transmitted through a first physical channel and a second signal component transmitted through a second physical channel, the first signal component comprising a first base layer carrying a first data stream and a first enhancement layer carrying a second data stream, the second signal component comprising a second base layer carrying the second data stream and a second enhancement layer carrying the first data stream;

receiving at a second antenna a second signal, the second signal comprising a third signal component transmitted through a third physical channel and a fourth signal component transmitted through a fourth physical channel, the third signal component comprising a third base layer carrying the first data stream and a third enhancement layer carrying the second data stream, the fourth signal component comprising a fourth base layer carrying the second data stream and a fourth enhancement layer carrying the first data stream;

estimating the first, second, third, and fourth physical channels to obtain one or more channel estimates;

separating the first and second signal components using the one or more channel estimates;

decoding the first data stream from the first base layer after the step of separating; and

decoding the second data stream from at least one layer selected from the first enhancement layer and the second base layer, after the step of separating;

wherein the first, second, third, and fourth signal components are hierarchically modulated using the same carrier frequency.

36. A method of operating a cellular radio network comprising a first cell, the first cell comprising a first transmit antenna and a second transmit antenna, the first and second transmit antennae being spatially diverse, the method comprising:

transmitting a first data stream on a first frequency through the first antenna to a plurality of user equipment devices; and

transmitting a second data stream on the first frequency through the second antenna to the plurality of user equipment devices.