Joint demodulation using spatial maximum likelihood

• US 6,148,041 A
• Filed: 05/07/1998
• Issued: 11/14/2000
• Est. Priority Date: 01/11/1994
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Dent, Paul W.
• Primary Examiner(s): Le, Amanda T.
• Application Number:
  US09/073,867
• Time in Patent Office: 922 Days
• Field of Search: 375/260, 375/262, 375/340, 375/341, 375/349, 375/347, 714/794, 714/796
• US Class Current: 375/340
• CPC Class Codes: G08B 3/1008 Personal calling arrangements or devices, i.e. paging systems selective calling systems and call receivers H04W84/00, H04W68/00
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/08 the units being spaced along or adjacent to a rectilinear path waveguide fed H01Q21/0037
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 1/126 having multiple inputs, e.g. auxiliary antenna for receiving interfering signal aerials in general H01Q
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: H04B 7/18567 Arrangements for providing additional services to the basic mobile satellite telephony service
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/021 Estimation of channel covariance
• CPC Class Codes: H04L 25/03203 Trellis search techniques
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 25/03299 with noise-whitening circuitry
• CPC Class Codes: H04L 25/03331 : Arrangements for the joint estimation of multiple sequences
• CPC Class Codes: H04W 16/02 : Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/14 : Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 74/08 : Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/025 : with acknowledge back capability
• CPC Class Codes: H04W 84/042 : Public Land Mobile systems, e.g. cellular systems
• CPC Class Codes: H04W 84/06 : Airborne or Satellite Networks space-based or airborne stations H04B7/185
• CPC Class Codes: H04W 88/022 : Selective call receivers
• CPC Class Codes: H04W 88/185 : Selective call encoders for paging networks, e.g. paging centre devices

Abstract

Methods and systems for processing signals in radio communication systems are described which include processes for handling co-channel interference while reducing the number of Viterbi states being processed. A spatial analogy to the Viterbi MLSE process is provided. Both the uplink and downlink cases are described.

Claims

1. A method for receiving a plurality of signals via a plurality of paths in which each path comprises an independent signal mixing process giving rise to an independent mixture of said signals, comprising the steps of:

applying said independent mixing processes to hypotheses of said signals to produce predictions of said independent mixtures;

comparing each of said predicted mixtures with a mixture received via a corresponding path and generating a mismatch indication; and

processing said mismatch indications to decode said signals.

2. A system according to claim 1 in which said processing step further comprises the step of determining the hypothesis which gives the lowest sum of said mismatches.

3. A system according to claim 1 in which said mismatch indications are the magnitude squared differences between predicted and received signal mixtures.

4. A system according to claim 1 in which said mismatches are a function of the magnitude squared of the difference between predicted and received signal mixtures and said processing determines which of said hypotheses maximizes the sum of said mismatches.

5. The system according to claim 4 in which said function is a negative exponential function.

6. A demodulator for a multi-channel receiver comprising:

means for receiving signals on each of a plurality of channels;

means for making sets of symbol hypotheses for signals received on each of said plurality of adjacent channels;

means for predicting said received signals using said sets of symbol hypotheses;

means for comparing said predicted signals with respective, actually-received, signals and calculating mismatches therebetween; and

means for accumulating said mismatches for each set of hypotheses for each signal and selecting a set having a lowest cumulative mismatch after processing signals received on each of said plurality of adjacent channels.