Systems and methods for improving range for multicast wireless communication

• US 20040219937A1
• Filed: 05/27/2004
• Published: 11/04/2004
• Est. Priority Date: 03/01/2002
• Status: Active Grant

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Vaidyanathan, Chandra, Sugar, Gary L.
• Granted Patent: US 7,570,921 B2
• Time in Patent Office: Days
• US Class Current: 455/500
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03445 Time domain
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Methods to optimize range of multicast signal communication in wireless communication applications that use range-enhanced techniques for directed signal communication. A multicast signal may be sent multiple times through each of a plurality of independent omnidirectional transmit antennas of a communication device to a plurality of other communication devices to improve packet error rate (PER) at a given range (i.e., SNR). More generally, the multicast message can be transmitted up to N times using up to N times using any set of N complex linearly independent N-dimensional transmit weight vectors v₁, . . . ,v_N associated with N plurality of transmit antennas that meets the power constraint ∥v_i∥²=1, i=0, . . . ,N−1, where the vector v_i is used for the ith transmission of the multicast signal.

Claims

1. In a wireless communication system having a plurality of communication devices in which directed communication between two communication devices is performed using range-enhanced communication techniques, a method for enhancing the range of communication for a signal transmitted from a first communication device intended for reception by a plurality of other communication device, comprising transmitting a signal intended for reception by the plurality of other communication devices one or more times through the plurality antennas of the first communication device, each time using transmit delay diversity.

2. A method for wireless communication comprising steps of:

a. transmitting a signal intended for a particular communication device from a plurality of antennas of the first communication device using antenna processing techniques to maximize the range of communication with the particular communication device; and

b. transmitting a signal intended for reception by a plurality of communication devices from the first communication device one or more times through the plurality antennas of the first communication device, each time using transmit delay diversity.

3. A method for wireless communication comprising the steps of:

a. receiving at a first communication device a first request-to-send (RTS) signal transmitted by a second communication device, wherein the first RTS signal requests reservation of a radio communication medium for transmission of a signal from the second communication device to the first communication device;

b. at the first communication device, generating at least one clear-to-send (CTS) signal that is addressed to the first communication device and including information to inform communication devices of an impending transmission on the radio communication medium;

c. transmitting the CTS signal from the first communication device with antenna processing parameters so as to cause a null at the second communication device but not at a plurality of other communication devices.

4. The method of claim 3, wherein the step of transmitting comprises transmitting the CTS signal using a transmit weight vector that is in the null space of H, where H represents the channel response matrix between the first communication device and the second communication device.

5. The method of claim 4, wherein the step of generating comprises generating at least first and second CTS signals, each of which is addressed to the first communication device, and is transmitted using a transmit weight vector that is in the null space of H.

6. The method of claim 5, wherein the step of transmitting comprises transmitting the first and second CTS signals with transmit weight vectors that are linearly independent.

7. The method of claim 3, and further comprising the steps of receiving a second RTS signal from the second communication device at the first communication device;

and transmitting a CTS signal addressed to the second communication device.

8. The method of claim 7, wherein the step of transmitting the CTS signal addressed to the second communication device comprises processing the CTS signal with transmit antenna weights associated with the plurality of antennas of the first communication device that optimize reception of the CTS signal by the second communication device.

9. The method of claim 8, and further comprising the step of receiving data from the second communication device at the plurality of antennas of the first communication device.

10. The method of claim 9, and further comprising the step of transmitting an acknowledgment (ACK) signal from the first communication device to the second communication device via the plurality of antennas using transmit antenna weights associated with the plurality of antennas of the first communication device that optimize reception of the CTS signal by the second communication device.

11. A medium encoded with instructions, that when executed, perform the steps of:

a. in response to a first request-to-send (RTS) signal transmitted by a second communication device and received by a first communication device, generating at least one clear-to-send (CTS) signal that is addressed to the first communication device and including information to inform communication devices of an impending transmission on the radio communication medium; and

b. processing the CTS signal using a transmit weight vector that is in the null space of H, where H represents the channel response matrix between the first communication device and the second communication device.

12. The medium of claim 11, and further encoded with instructions that generate at least first and second CTS signals and process the first and second CTS signals with transmit weight vectors that are linearly independent.

13. The medium of claim 11, and further encoded with instructions that, in response to receiving a second RTS signal from the second communication device, generate a CTS signal addressed to the second communication device.

14. The medium of claim 13, and further encoded with instructions to process the CTS signal addressed to the second communication device with transmit antenna weights associated with the plurality of antennas of the first communication device that optimize reception of the CTS signal by the second communication device.

15. The medium of claim 14, and further encoded with instructions that, in response to receiving data from the first communication device, generate an acknowledgment (ACK) signal, and processing the ACK signal with transmit antenna weights associated with the plurality of antennas of the first communication device that optimize reception of the CTS signal by the second communication device.

16. A communication device comprising the medium of claim 11, and further comprising:

a. a receiver that downconverts signals received by the plurality of antennas;

b. a transmitter that upconverts signals to be transmitted; and

c. a processor coupled to the transmitter and the receiver that processes instructions encoded on the medium.

17. An integrated circuit comprising the medium of claim 11.