Increasing capacity in wireless broadcast systems using distributed transmission/directional reception (DTDR)

• US 5,345,599 A
• Filed: 02/21/1992
• Issued: 09/06/1994
• Est. Priority Date: 02/21/1992
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: Paulraj, Arogyaswami J., Kailath, Thomas
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): PHAM, CHI H
• Application Number:
  US07/839,624
• Time in Patent Office: 928 Days
• Field of Search: 455/49.1, 455/51.1, 455/51.2, 455/59, 455/60, 455/61, 455/101, 455/103, 455/105, 455/137, 455/273, 455/278.1, 375/38, 375/40, 342/367, 342/463-465, 358/133, 358/138, 358/141, 358/146, 370/59, 370/63, 370/64
• US Class Current: 455/500
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04H 20/18 Arrangements for synchronising broadcast or distribution via plural systems
• CPC Class Codes: H04H 20/33 by plural channels
• CPC Class Codes: H04N 7/015 High-definition television systems
• CPC Class Codes: H04N 7/127 Systems in which different parts of the picture signal frequency band are individually processed, e.g. suppressed, transposed

Abstract

A method and apparatus for increasing the capacity of wireless broadcast communications system from a central studio to a plurality of users in a service area is disclosed. Given a source signal whose high information rate exceeds the practical information carrying capacity of the available broadcast channel bandwidth, the invention increases the effective capacity of the broadcast system to effectively communicate such a source signal. The high-rate signal is split into several low-rate signals such that each can be accommodated within the allocated bandwidth. These low-rate signals are transmitted from spatially separated transmitters, all radiating into the service area in the same frequency channel. Each receiver uses a plurality of antennas to receive these multiple cochannel signals that arrive from different directions-of-arrival. The receiver exploits the directions-of-arrival differences of these cochannel signals to separate them into the individually transmitted signals. The separated signals are then demodulated to extract the information signals which are then combined to obtain the original high-rate source signal. Thus, the broadcast information capacity can be increased several-fold.

Claims

1. A wireless broadcast system for transmission of a source signal from a plurality of spatially separated transmitters on a common frequency channel to at least one receiver located in a service area, said system comprising in combination

demultiplexing means for splitting said source signal into a plurality of transmitted signals, one for each of said transmitters,

conveying means for sending said transmitted signals one each to said transmitters,

transmitting means including said transmitters for broadcasting said transmitted signals into said service area in said frequency channel so as to reach said receiver,

receiving means including said receiver and plural receiving antennas for making measurements of signals received by said receiver, said received signals resulting from signals transmitted by said transmitters, said measurements being composed of different combinations of said transmitted signals,

processing means for obtaining estimates of said transmitted signals from said measurements, reducing interference to acceptable levels,

multiplexing means for combining said estimates of said transmitted signals so as to estimate said source signal, reducing interference to acceptable levels,

whereby the information carrying capacity of the wireless broadcast system is increased.

2. A wireless broadcast system for transmission of a plurality of source signals from a plurality of spatially separated transmitters on a common frequency channel to at least one receiver located in a service area, said system comprising in combination

combining means for joining said source signals into a composite source signal,

demultiplexing means for splitting said composite source signal into a plurality of transmitted signals, one for each of said transmitters,

conveying means for sending said transmitted signals one each to said transmitters,

transmitting means including said transmitters for broadcasting said transmitted signals into said service area in said frequency channel so as to reach said receiver,

receiving means including said receiver and plural receiving antennas for making measurements of signals received by said receiver, said received signals resulting from signals transmitted by said transmitters, said measurements being composed of different combinations of said transmitted signals,

processing means for obtaining estimates of said transmitted signals from said measurements, reducing interference to acceptable levels,

multiplexing means for combining said estimates of said transmitted signals so as to estimate said composite source signal, reducing interference to acceptable levels,

separating means for decomposing said estimated composite source signal into said source signals,

whereby a plurality of independent source signals can be transmitted in the same frequency channel.

3. Apparatus for transmitting an information signal and for receiving said information signal in a frequency channel having a bandwidth less than the bandwidth of said information signal, said apparatus comprising:

means for splitting said information signal into a plurality of information sub-signals, each sub-signal having a bandwidth no greater than said bandwidth of said frequency channel,

transmitting means for transmitting in said frequency channel each of said sub-signals to a receiver, said transmitting means including a plurality of physically dispersed transmitters each transmitting one of said sub-signals,

receiving means for receiving and processing said information sub-signals wherein said information sub-signals are retrieved, and

means for combining said information sub-signals to reconstruct said information signal.

4. A method of transmitting an information signal to a receiver in a frequency channel having a bandwidth less than the bandwidth of said information signal and receiving said information signal at said receiver, said method comprising the steps of:

splitting said information signal into a plurality of information sub-signals, each sub-signal having a bandwidth no greater than said bandwidth of said frequency channel,

transmitting in said frequency channel each of said information sub-signals to said receiver from a plurality of dispersed transmitters with each transmitter transmitting one of said information sub-signals,

receiving and processing said information sub-signals with receiving means wherein said information sub-signals are retrieved, and

combining said information sub-signals to reconstruct said information signal.