Method of and apparatus for reducing the complexitiy of a diversity combining and sequence estimation receiver

• US 5,481,572 A
• Filed: 08/02/1994
• Issued: 01/02/1996
• Est. Priority Date: 08/02/1994
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Skold, Johan, Eriksson, Per-Olof
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US08/284,761
• Time in Patent Office: 518 Days
• Field of Search: 375/232, 375/267, 375/340-341, 375/347, 371/43
• US Class Current: 375/347
• 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: H04L 1/02 by diversity reception

Abstract

Signals in synchronizing sequences and data sequences are transmitted over a fading channel to a sequence estimation receiver. The signals are received by a plurality of mutually separated antennas and sampled to produce received antenna signals (S_in,r (k)). Using the received antenna signals, part transmission channel estimates (h_est,r) are formed for each antenna. These part channel estimates are used to form precomputed metric values (f_a,r ((ΔT_ij),g_a (ΔT_ij)). For the sequence estimation algorithm, branch metric values (m(ΔT_ij,k)) are formed by combining the precomputed metric values with the received antenna signals for state transitions (ΔT_ij). For one state transition there is formed a metric value such as the sum of a metric value (M(T_j,k-1)) for an old state (T_j) at a preceeding sampling time point (k-1) with a branch metric value (m(ΔT_ij,k)). Corresponding metric values are formed for all state transitions to the new state (T_i) and the state corresponding to the smallest of these metric values is chosen in accordance with the sequence estimation algorithm.

Claims

1. A method for reducing the influence of signal fading and time dispersion in a radio communication system, comprising the steps of:

a) generating and transmitting a signal representing a transmitted symbol sequence;

b) receiving the signal on at least two mutually separated antennas;

c) sampling the signals received from the antennas to form received antenna signals;

d) determining channel estimates for each of said antennas using said received antenna signals;

e) processing said channel estimates to form precomputed metric values;

f) forming branch metrics using said precomputed metric values and said received antenna signals; and

g) estimating said transmitted symbol sequence using a sequence estimation algorithm employing said branch metrics.

2. The method of claim 1, wherein said sequence estimation algorithm is a Viterbi algorithm.

3. The method of claim 1, wherein said sampling is effected using log-polar signal processing.

4. A method for reducing the influence of signal fading and time dispersion in a radio communication system, comprising the steps of:

a) generating and transmitting a signal representing a transmitted symbol sequence;

b) receiving the signal on at least two mutually separated antennas;

c) sampling the signals received from the antennas to form received antenna signals;

d) determining channel estimates for each of said antennas using said received antenna signals;

e) generating symbol sequences and processing said channel estimates with said symbol sequences to produce assumed received signals;

f) processing said assumed received signals to form precomputed metric values;

g) forming branch metrics using .said precomputed metric values and said received antenna signals; and

h) estimating said transmitted symbol sequence using a sequence estimation algorithm employing said branch metrics.

5. The method of claim 4, wherein said sequence estimation algorithm is a Viterbi algorithm.

6. The method of claim 4, wherein said sampling is effected using log-polar signal processing.

7. An apparatus for reducing the influence of fading and time dispersion, comprising;

transmitter means for generating and transmitting a signal representing a transmitted symbol sequence;

receiving means for receiving the signal on at least two mutually separated antennas;

analog to digital converter means for sampling the signals received from said antennas to form received antenna signals;

channel estimation means coupled to the received antenna signals for determining channel estimates for each of said antennas using said received antenna signals;

metric calculating means for processing said channel estimates to form precomputed metric values; and

analyzer means for estimating said transmitted symbol sequence using a sequence estimation algorithm employing said received antenna signals and said precomputed metric values.

8. The apparatus of claim 7, wherein said sequence estimation algorithm is a Viterbi algorithm.

9. The apparatus of claim 7, wherein said sampling is effected using log-polar signal processing.

10. An apparatus for reducing the influence of signal fading and time dispersion in a radio communication system, comprising:

transmitter means for generating and transmitting a signal representing a transmitted symbol sequence;

receiver means for receiving the signal on at least two mutually separated antennas;

analog to digital conversion means for sampling the signal received from the antennas to form received antenna signals;

channel estimation means coupled to the received antenna signals for determining channel estimates for each of said antennas using said received antenna signals;

symbol sequence generation means for generating symbol sequences and processing said channel estimates with said symbol sequences to produce assumed received signals;

processor means for processing said assumed received signals to form precomputed metric values and forming branch metrics using said precomputed metric values and said received antenna signals; and

analyzer means for estimating said transmitted symbol sequences using a sequence estimation algorithm employing said branch metrics.

11. The apparatus of claim 10, wherein said sequence estimation algorithm is a Viterbi algorithm.

12. The apparatus of claim 10, wherein said sampling is effected using log-polar signal processing.