Method and arrangement for estimating data sequences transmsitted using Viterbi algorithm

• US 5,325,402 A
• Filed: 04/30/1992
• Issued: 06/28/1994
• Est. Priority Date: 04/30/1991
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ushirokawa, Akihisa
• Primary Examiner(s): Chin, Stephen
• Application Number:
  US07/876,326
• Time in Patent Office: 789 Days
• Field of Search: 375/38, 375/39, 375/42, 375/58, 375/67, 375/94, 375/99, 371/43, 371/44, 371/45, 341/51, 341/81, 329/304
• US Class Current: 375/341
• CPC Class Codes: H04L 25/03292 with channel estimation circuitry

Abstract

To reduce the number of operations required for estimating a transmitted data sequence using a Viterbi algorithm, a method and apparatus are provided for (a) storing a plurality of sampled values of an incoming signal in a shift register in a predetermined interval; (b) receiving a plurality of the sampled values from the shift register, and estimating channel responses, at a current time point, of a plurality of first signal sequences which are derived from the plurality of sampled values and each of the length of which is reduced by deleting at least one sampled data at the oldest time point; (c) receiving the channel responses estimated at (b) and checking to see if each of the estimated channel responses is determinate, producing a first signal sequence if an estimated channel response of a first signal sequence is found determinate, and producing an estimated channel response as a first signal sequence at a time point preceding the current time point in the event that the estimated channel response of the first signal sequence is found indeterminate; (d) storing the first signal sequences produced at (c), and producing an estimated channel response which has been stored at a time point preceding the current time point; and (e) determining a plurality of branch metrics using the estimated channel response obtained at (c) and an original first signal sequence before the original first signal sequence is reduced in length.

Claims

1. A method of estimating a transmitted data sequence using a Viterbi algorithm, comprising the steps of:

(a) storing, at a predetermined time interval, a plurality of sampled values of an incoming signal in a shift register;

(b) receiving a plurality of the sampled values from said shift register, and estimating channel responses, at a current time point, of a plurality of first signal sequences which are derived from said plurality of sampled values and each of the length of which is reduced by deleting at least one sampled data at the oldest time point;

(c) receiving the channel responses estimated in step (b) and checking to see if each of the estimated channel responses is determinate, producing a first signal sequence if an estimated channel response of a first signal sequence is found determinate, and producing an estimated channel response as a first signal sequence at a time point preceding the current time point in the event that the estimated channel response of the first signal sequence is found indeterminate;

(d) storing the first signal sequences produced at step (c), and producing an estimated channel response which has been storeds at a time point preceding the current time point; and

(e) determining a plurality of branch metrics using the estimated channel response obtained at step (c) and an original first signal sequence before the original first signal sequence is reduced in lenght.

2. A method of estimating a transmitted data sequence using a Viterbi algorithm, comprising the steps of:

(a) storing, at a predetermined time interval, a plurality of sampled values of an incoming signal in a shift register;

(b) receiving a plurality of the sampled values from said shift register, and estimating channel responses, at a current time point, of a plurality of first signal sequences which are derived from said plurality of sampled values, the length of each of the first signal sequences being reduced using phase-shifts between adjacent sampled values;

(c) receiving the channel responses estimated in step (b) and checking to see if each of the estimated channel responses is determinate, producing a first signal sequence if an estimated channel response of a first signal sequence is found determinate, and producing an estimated channel response as a first signal sequence at a time point preceding the current time point in the event that the estimated channel response of the first signal sequence is found indeterminate;

(d) storing the first signal sequences produced at step (c), and producing an estimated channel response which has been stored at a time point preceding the current time point; and

(e) determining a plurality of branch metrics using the estimated channel response obtained at step (c) and an original first signal sequence before the original first signal sequence is reduced in length.

3. An apparatus for estimating a transmitted data sequence using a Viterbi algorithm, comprising:

first means for storing, at a predetermined time interval, a plurality of sampled values of an incoming signal in a shift register;

second means for receiving a plurality of the sampled values from said shift register, and estimating channel responses, at a current time point, of a plurality of first signal sequences which are derived from said plurality of sampled values and a length of each of the first signal sequences being reduced by deleting at least one sampled data at the oldest time point;

third means for receiving the channel responses estimated by said second means and checking to see if each of the estimated channel responses is determinate, producing a first signal sequence if an estimated channel response of a first signal sequence is found determinate, and producing an estimated channel response as a first signal sequence at a time point preceding the current time point in the event that the estimated channel response of the first signal sequence is found indeterminate;

fourth means for storing the first signal sequences produced by said third means and producing an estimated channel response which has been stored at a time point preceding the current time point; and

fifth means for determining a plurality of branch metrics using the estimated channel response obtained from said third means and an original first signal sequence before the original first signal sequence is reduced in length.

4. An apparatus for estimating a transmitted data sequence using a Viterbi algorithm, comprising:

first means for storing, at a predetermined time interval, a plurality of sampled values of an incoming signal in a shift register;

second means for receiving a plurality of the sampled values from said shift register, and estimating channel responses, at a current time point, of a plurality of first signal sequences which are derived from said plurality of sampled values, the length of each of the first signal sequences being reduced using phase-shifts between adjacent sampled values;

third means for receiving the channel responses estimated in said second means and checking to see if each of the estimated channel responses is determinate, producing a first signal sequence if an estimated channel response of a first signal sequence is found determinate, and producing an estimated channel response as a first signal sequence at a time point preceding the current time point in the event that the estimated channel response of the first signal sequence is found indeterminate;

fourth means for storing the first signal sequences produced by said third means and producing an estimated channel response which has been stored at a time point preceding the current time point; and

fifth means for determining a plurality of branch metrics using the estimated channel response obtained from said third means and an original first signal sequence before the original first signal sequence is reduced in length.