CHANNEL USAGE BEACON SIGNAL DESIGN FOR COOPERATIVE COMMUNICATION SYSTEMS

• US 20150110066A1
• Filed: 10/20/2014
• Published: 04/23/2015
• Est. Priority Date: 10/21/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gaal, Peter, Bhushan, Naga, Chen, Wanshi, Xu, Hao, Yerramalli, Srinivas, Damnjanovic, Aleksandar, Luo, Tao, Malladi, Durga Prasad, Wei, Yongbin, Ji, Tingfang
• Granted Patent: US 9,844,057 B2
• Time in Patent Office: Days
• US Class Current: 370/330
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

Design of channel usage beacon signals (CUBS) in cooperative networks is disclosed. After detecting a clear channel assessment (CCA), a transmitter selects a configuration of a CUBS associated with the transmitter based on the CCA opportunity assigned to the network. The configuration of the CUBS associated with the transmitter may include a set of frequency subcarriers for CUBS transmissions. The transmitter transmits the CUBS according to transmission characteristics based on the CCA opportunity. In additional aspects, randomization may be introduced into the frequency subcarrier allocations of CUBS configurations where the transmitter receives assignment of virtual frequency subcarriers for CUBS transmissions and maps the virtual subcarrier to physical frequency subcarriers for CUBS transmission. Additional aspects allow for pattern offset values to be determined independently from the transmitter cell identifier. In such aspects, the assigned pattern offsets may be cell identifier-independent, while others may be cell identifier-dependent.

Claims

1. A method of wireless communication, comprising:

detecting, by a transmitter in preparation for transmission of a set of data over an unlicensed band, a clear channel assessment (CCA) in a CCA opportunity assigned to a network of the transmitter;

selecting, by the transmitter, a configuration of a channel usage beacon signal (CUBS) associated with the transmitter based on the CCA opportunity assigned to the network of the transmitter, wherein the configuration of the CUBS associated with the transmitter includes a set of frequency subcarriers for CUBS transmissions; and

transmitting, by the transmitter, the CUBS according to transmission characteristics based on the CCA opportunity.

2. The method of claim 1, wherein the set of frequency subcarriers for CUBS transmission is a subset of all subcarriers available for CUBS transmission.

3. The method of claim 2, wherein the subset is one of a plurality of non-overlapping subsets.

4. The method of claim 3, wherein a number of the plurality of non-overlapping subsets is larger or equal to a number of a total number of available CCA opportunities.

5. The method of claim 4, wherein each CCA opportunity is associated with a unique non-overlapping subset of the plurality of non-overlapping subsets.

6. The method of claim 3, wherein the number of the plurality of non-overlapping subsets is smaller than the number of the total number of available CCA opportunities.

7. The method of claim 6, wherein the association between each CCA opportunity and the plurality of non-overlapping subsets is time slot dependent.

8. The method of claim 7, wherein there is a time slot for each CCA opportunity in which the CCA opportunity is mapped to a non-overlapping subset of the plurality of non-overlapping subsets to which no other CCA opportunity is mapped.

9. The method of claim 1, further including:

determining, by the transmitter in response to the clear CCA, an expected duration of transmission for the set of data; and

selecting, by the transmitter, the configuration of the CUBS associated with the transmitter based on the expected duration of the transmission.

10. The method of claim 9, wherein the selecting the configuration includes:

selecting a first configuration, when the duration fails to exceed a predetermined time; and

selecting a second configuration, when the duration exceeds the predetermined time.

11. The method of claim 9, wherein the selecting the configuration includes:

selecting a first configuration, when the duration fails to exceed a predetermined time; and

selecting a second configuration, when the duration exceeds the predetermined time.

12. The method of claim 9, wherein the transmitting according to transmission characteristics includes:

transmitting the CUBS in each of one or more symbols of a subframe associated with the CCA opportunity, wherein the transmitting begins in a first symbol of the one or more symbols related to the CCA opportunity.

13. The method of claim 9, wherein the transmitting according to transmission characteristics includes:

selecting an orthogonal channel from a plurality of orthogonal channels associated with a set of available CCA opportunities, wherein the selected orthogonal channel corresponds to the detected CCA opportunity.

14. The method of claim 9, wherein the transmitting according to transmission characteristics includes:

transmitting, by the transmitter, the CUBS over two or more antennas, wherein the CUBS transmitted over each of the two or more antennas is phase shifted from the CUBS transmitted over the other of the two or more antennas.

15. The method of claim 9, wherein the transmitting according to transmission characteristics includes:

transmitting, by the transmitter, the CUBS is transmitted over two or more antennas using a single port, wherein each CUBS transmitted is time offset from each other.

16. The method of claim 9, further including:

generating the CUBS by;

setting each odd-numbered resource elements of a frequency tone map of the CUBS to zero; and

transforming the frequency tone map of the CUBS into a time domain signal prior to the transmitting, wherein the time domain signal includes an lengthened cyclic prefix.

17. A method of wireless communication, comprising:

detecting, by a receiver, a channel usage beacon signal (CUBS) in a clear channel assessment (CCA) opportunity assigned to a network of the receiver, wherein a configuration of the CUBS identifies a transmitter in communication with the receiver;

setting an automatic gain control (AGC) by the receiver based on the CUBS;

determining, by the receiver, an expected transmission time from the transmitter based on the configuration;

receiving, by the receiver, data transmissions from the transmitter within the expected transmission time using the AGC; and

deactivating the receiving after the expected transmission time.

18. The method of claim 17, wherein the determining includes one of:

detecting a first configuration of the CUBs, wherein the first configuration indicates the expected transmission time of a half-length frame and further indicates one or more system signals are located within the half-length frame;

or

detecting a second configuration of the CUBs, wherein the second configuration indicates the expected transmission time of a full-length frame and further indicates one or more system signals are located within the full-length frame.

19. The method of claim 17, further including:

searching a plurality of resource elements of the CCA opportunity for the CUBS identifying the, wherein the searching includes;

searching for a pattern indicative of the CUBS every three resource elements from a first resource element in the plurality of resource elements;

searching for the pattern indicative of the CUBS every three resource elements from a second resource element shifted from the first resource element by one resource element; and

searching for the pattern indicative of the CUBS every three resource elements from a third resource element shifted from the second resource element by one resource element.

20. The method of claim 17, further including:

detecting a neighbor network CUBS in a neighbor network CCA opportunity;

determining an observed power difference between the CUBS and the neighbor network CUBS;

performing, by the transmitter, no interference cancelation when the observed power difference fails to exceed a predetermined threshold; and

performing, by the transmitter, interference cancellation when the observed power difference exceeds the predetermined threshold.

21. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code for causing a computer to detect, by a transmitter in preparation for transmission of a set of data over an unlicensed band, a clear channel assessment (CCA) in a CCA opportunity assigned to a network of the transmitter;

program code for causing the computer to select, by the transmitter, a configuration of a channel usage beacon signal (CUBS) associated with the transmitter based on the CCA opportunity assigned to the network of the transmitter, wherein the configuration of the CUBS associated with the transmitter includes a set of frequency subcarriers for CUBS transmissions; and

program code for causing the computer to transmit, by the transmitter, the CUBS according to transmission characteristics based on the CCA opportunity.

22. An apparatus configured for wireless communication, the apparatus comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured;

to detect, by a transmitter in preparation for transmission of a set of data over an unlicensed band, a clear channel assessment (CCA) in a CCA opportunity assigned to a network of the transmitter;

to select, by the transmitter, a configuration of a channel usage beacon signal (CUBS) associated with the transmitter based on the CCA opportunity assigned to the network of the transmitter, wherein the configuration of the CUBS associated with the transmitter includes a set of frequency subcarriers for CUBS transmissions; and

to transmit, by the transmitter, the CUBS according to transmission characteristics based on the CCA opportunity.

23. The apparatus of claim 22, further including configuration of the at least one processor:

to determine, by the transmitter in response to the clear CCA, an expected duration of transmission for the set of data; and

to select, by the transmitter, the configuration of the CUBS associated with the transmitter based on the expected duration of the transmission.

24. The apparatus of claim 22, wherein the configuration of the at least one processor to select the configuration includes configuration of the at least one processor:

to select a first configuration, when the duration fails to exceed a predetermined time; and

to select a second configuration, when the duration exceeds the predetermined time.

25. The apparatus of claim 22, wherein the configuration of the at least one processor to select the configuration includes configuration of the at least one processor:

to select a first configuration, when the duration fails to exceed a predetermined time; and

to select a second configuration, when the duration exceeds the predetermined time.

26. The apparatus of claim 22, wherein the configuration of the at least one processor to transmitting according to transmission characteristics includes configuration to transmit the CUBS in each of one or more symbols of a subframe associated with the CCA opportunity, wherein the transmission begins in a first symbol of the one or more symbols related to the CCA opportunity.

27. The apparatus of claim 22, wherein the configuration of the at least one processor to transmit according to transmission characteristics includes configuration to select an orthogonal channel from a plurality of orthogonal channels associated with a set of available CCA opportunities, wherein the selected orthogonal channel corresponds to the detected CCA opportunity.

28. The apparatus of claim 22, wherein the configuration of the at least one processor to transmit according to transmission characteristics includes configuration to transmit, by the transmitter, the CUBS over two or more antennas, wherein the CUBS transmitted over each of the two or more antennas is phase shifted from the CUBS transmitted over the other of the two or more antennas.

29. The apparatus of claim 22, wherein the configuration of the at least one processor to transmit according to transmission characteristics includes configuration to transmit, by the transmitter, the CUBS is transmitted over two or more antennas using a single port, wherein each CUBS transmitted is time offset from each other.

30. The apparatus of claim 22, further including configuration of the at least one processor:

to generate the CUBS by;

setting each odd-numbered resource elements of a frequency tone map of the CUBS to zero; and

transforming the frequency tone map of the CUBS into a time domain signal prior to the transmitting, wherein the time domain signal includes an lengthened cyclic prefix.