Systems and methods for improving range for multicast wireless communication

• US 6,862,456 B2
• Filed: 06/19/2002
• Issued: 03/01/2005
• Est. Priority Date: 03/01/2002
• Status: Expired due to Fees

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: Cognio, Inc. (Cisco Systems, Inc.)
• Inventors: Sugar, Gary L., Vaidyanathan, Chandra
• Primary Examiner(s): Gesesse, Tilahun
• Application Number:
  US10/174,690
• Publication Number:
  US 20030181165A1
• Time in Patent Office: 986 Days
• Field of Search: 455/503, 455/502, 455/517, 455/518, 455/521, 455/561, 455/562.1, 370/445, 370/328, 370/349
• US Class Current: 455/503
• 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 multicast signals from a first communication device to a plurality of other communication device, comprising transmitting a signal intended for reception by the plurality of other communication devices up to N times 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 i^th transmission of the signal.

2. The method of claim 1, wherein N=4, and the transmit weight vectors are (1000)^T, (0100)^T, (0010)^T and (0001)^T.

3. The method of claim 1, wherein the step of transmitting comprises transmitting the signal with the transmit weight vector v_mod(i,N), for the i^th transmission of the signal, where mod(m,n) denotes the remainder of m divided by n, where i is not bounded by N.

4. The method of claim 3, wherein the signal includes information containing at least one of an identifier of a wireless network, data rates supported by the wireless network, and contention-free parameters and traffic information of data to be transmitted by the first communication device.

5. The method of claim 1, and further comprising the step of determining whether the first communication device is operating in an extended range mode, and if so, executing the step of transmitting.

6. The method of claim 5, and further comprising the step of transmitting the signal once from one of the plurality of antennas if the first communication device is not operating in the extended range mode.

7. The method of claim 1, wherein the signal includes information which informs the plurality of other communication devices not to transmit on a radio frequency medium for a time interval.

8. The method of claim 7, wherein the signal further includes information that informs the plurality of other communication devices the amount of time before the radio frequency medium will become available.

9. The method of claim 8, after transmission of the signal, further comprising the step of transmitting a first signal containing information including at least one of an identifier of a wireless network, rates supported by the wireless network, and contention-free parameters followed by a second signal containing information about frames that are buffered at the first communication device for certain ones of the plurality of other communication devices.

10. The method of claim 9, wherein the step of transmitting the first signal comprises transmitting the first signal via one of the plurality of antennas of the first communication device.

11. 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 the plurality of other communication devices 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 i^th transmission of the signal.

12. The method of claim 11, wherein the step of transmitting comprises transmitting the signal intended for a plurality of communication devices with the transmit weight vector v_mod(i,N), for the i^th transmission of the signal, where mod(m,n) denotes the remainder of m divided by n. where number transmissions i is not bounded by N−

1.

13. A medium encoded with instructions that, when executed, perform a method comprising a step of processing a signal intended for reception by a plurality of communication devices for transmission up to N times with 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 i^th transmission of the signal.

14. The medium of claim 13, and further encoded with instructions that, when executed, process a signal intended for a particular communication device via the N plurality of antennas using antenna processing techniques to maximize the range of communication of the signal to the particular communication device.

15. The medium of claim 14, wherein the instructions to process a signal intended for a particular communication device comprise instructions to process the signal with transmit antenna weights, corresponding to the N plurality of antennas that optimize reception of the signal by the particular communication device.

16. The medium of claim 13, and further encoded with instructions that, when executed, generate the signal to contain information including at least one of an identifier of a wireless network, data rates supported by the wireless network, and contention-free parameters and traffic information of data to be transmitted by the first wireless communication device.

17. The medium of claim 13, and further encoded with instructions that, when executed, generate the signal to include information that informs the plurality of the other communication devices of an impending transmission on a radio communication medium.

18. The medium of claim 13, and further encoded with instructions that, when executed, process the signal with the transmit weight vector v_mod(i,N), for the i^th transmission of the signal, where mod(m,n) denotes the remainder of m divided by n, where number transmissions i is not bounded by N−

1.

19. The medium of claim 13, wherein instructions are implemented by field programmable gates.

20. An integrated circuit comprising the medium of claim 13.