Bandwidth-efficient wireless network modem

• US 20030026356A1
• Filed: 04/18/2002
• Published: 02/06/2003
• Est. Priority Date: 04/18/2001
• Status: Active Grant

• Current Assignee: Collision Communications, Inc. (Concert Technology Corporation)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Brommer, Karl D.
• Granted Patent: US 7,233,620 B2
• Time in Patent Office: Days
• US Class Current: 375/324
• CPC Class Codes: H04B 1/7105 Joint detection techniques, e.g. linear detectors
• CPC Class Codes: H04B 1/71057 using maximum-likelihood sequence estimation [MLSE]
• CPC Class Codes: H04B 2201/709709 Methods of preventing interference

Abstract

Wireless communication network dynamically assigning communicators to allocated channels by considering the interference and noise environment to maximize the number of communicators and effective bandwidth of the channel. The present invention provides a digital wireless modem capable of measuring interference and noise in a channel, signaling the information on a control channel, accepting dynamic channel assignments from a controlling element and demodulating signals in the presence of interference and noise. The modem uses a demodulator capable of recovering information from data signals in the presence of noise and interference stronger than the primary signal, and there is a controlling element for transmitting noise and interference measurements to a central network controller and a controlling element for determining channel assignments with the central network controller and setting the modem to the correct transmission and reception channel.

Claims

1. A bandwidth efficient modem in a multi-user environment for determining whether additional users can be added to a system, comprising:

a front end unit for processing input received signals into a baseband waveform;

a baseband waveform processor performing parameter estimation and demodulation of said baseband waveform;

a digital signal processor for reconstructing an estimate of each said interfering signal and calculating a noise power, wherein said noise power is used to determine whether there is a sufficient noise margin to add said additional users, and wherein said reconstructing requires data from said parameter estimation and demodulation; and

a waveform generator for processing channel communications, wherein said channel communications consist of message and signal information, communicated to said system.

2. The bandwidth efficient modem according to claim 1, further comprising a single antenna with diplexer coupled to said front end unit for transmission and reception.

3. The bandwidth efficient modem according to claim 1, further comprising a reception antenna and a transmitter antenna coupled to said front end.

4. The bandwidth efficient modem according to claim 1, wherein said parameter estimation is performed by a parameter estimator that estimates amplitudes, carrier phases, carrier frequencies, symbol rates and symbol phases for each of said interfering signals.

5. The bandwidth efficient modem according to claim 1, wherein said demodulation is performed by a joint detector in said baseband waveform processor, wherein said joint detector demodulates said interfering signals and produces a set of bit values and bit error rates for each signal.

6. A bandwidth efficient modem according to claim 1, wherein said demodulation is a processing scheme selected from the group comprising:

optimal maximum likelihood multi user detection (MUD), maximum likelihood MUD, maximum likelihood sequence estimation, successive interference cancellation, TurboMUD, iterative MUD, and linear algebra based MUD.

7. The bandwidth efficient modem according to claim 1, wherein said demodulation processes said baseband waveform in the presence of noise and interference stronger than an information signal.

8. A bandwidth efficient system for a communications network, comprising:

a plurality of bandwidth efficient modems each interconnected to said network by a traffic channel and a signaling channel, wherein said modems process interference and noise levels in said traffic channel and recover information signals of said traffic channel; and

a central network controller coupled to said bandwidth efficient modems, wherein said controller monitors signal quality of each said traffic channel and dynamically allocates channel assignments to said bandwidth efficient modems according to said interference and noise levels.

9. The bandwidth efficient system according to claim 8, wherein said network is heterogeneous and further comprising one or more legacy modems coexisting on said network with said bandwidth efficient modems.

10. The bandwidth efficient system according to claim 8, wherein a means for connecting said modem on said network is selected from the group comprising:

bi-directional channels, indirect through a hub element, and directly via a hardwire connection.

11. The bandwidth efficient system according to claim 8, wherein said signaling channel transfers channel communications based upon conditions selected from the group comprising:

a request from said network controller;

a time interval, and a measured signal level.

12. The bandwidth efficient system according to claim 11, wherein said channel communication comprises channel status parameters, channel service request messages, and network messages.

13. The bandwidth efficient system according to claim 8, wherein said central network is coupled to said modems as selected from the group comprising:

a star network and a mesh network.

14. The bandwidth efficient system according to claim 13, further comprising redundancy wherein each of said bandwidth efficient modems is functional as a network controller.

15. A method of efficiently allocating channels on a communications network having a network controller coupled to a plurality of bandwidth efficient terminals, comprising the steps of:

processing a received signal into a baseband waveform in each of said terminals;

measuring interference and noise levels in a channel of said baseband waveform;

transmitting said interference and noise levels from said terminals to said network controller;

processing channel assignments in said network controller based on said interference and noise levels; and

sending transmission and reception channel assignments from said network controller to said terminals.

16. The method of efficiently allocating channels according to claim 15, further comprising the step of assigning bandwidth efficient modems to channels already occupied by other modems when there is sufficient signal-to-noise margin.

17. The method of efficiently allocating channels according to claim 15, further comprising the step of setting a signal level sufficiently low to fall within carrier-to-interfernece level requirements where a channel is occupied by a legacy terminal.

18. The method of efficiently allocating channels according to claim 15, further comprising the step of setting a signal level sufficiently high where a channel is occupied by a bandwidth efficient terminal.

19. The method of efficiently allocating channels according to claim 15, wherein said step of measuring comprises the steps of parameter estimation and demodulation.

20. The method of efficiently allocating channels according to claim 15, wherein said network controller is a bandwidth efficient terminal.