Back to results
US 7,072,926 B2Granted
Blind transport format detection system and method with logarithm approximation for reliability figure
AssigneeTexas Instruments Incorporated
InventorsToshio Nagata, Mitsuhiko Yagyu
Life of this patent
Estimating the term…
Abstract
Blind transport format detection with sliding window trace-back for evaluating decodings to candidate block lengths together with piecewise linear approximation of the reliability figure (logarithm of ratio of maximum survivor path metric minus minimum survivor path metric divided by 0 state path metric minus minimum survivor path metric) with a small lookup table plus simple logic.
Claims3
A method of reliability figure computation for blind transport format detection, comprising:
- (a) providing N-bit numbers c and d where N a positive integer and d is less than or equal to c and where c=amax−amin and d=a0−amin with amax and amin are the maximum and minimum path metric values, respectively, among survivor paths at a possible block end, and a0 is the path metric value of the 0 state at said possible block end;
- (b) extracting M-bit number m from said c where M is a positive integer less than N, said m aligned to the most significant non-zero bit of c;
- (c) extracting M-bit number n from said d, said n aligned to said m;
- (d) piecewise linearly approximating a logarithm of said m;
- (e) adjusting the approximation of step (d) by a table entry;
- (f) piecewise linearly approximating a logarithm of said n;
- (g) adjusting the approximation of step (f) by a table entry;
- and
- (h) approximating a logarithm of the quotient d/c by the difference of results of step (g) and step (e) whereby a reliability figure is approximated.
6 more elements
A method of reliability figure computation for blind transport format detection, comprising:
- (a) providing N-bit positive integer c=x1x2 . . . xN with N a positive integer and x1 the most significant bit and xN the least significant bit and where c=amax−amin and d=a0−amin with amax and amin are the maximum and minimum path metric values, respectively, among survivor paths at a possible block end, and a0 is the path metric value of the 0 state at said possible block end;
- (b) providing N-bit positive integer d=y1y2 . . . yN with y1 the most significant bit and yN the least significant bit and with d less than or equal to c;
- (c) extracting M-bit number m from said c, said m with most significant bit aligned to xj of said c where x1, x2, . . . , xk−1 are all 0 and xk is 1 where k is a positive integer with 1≦k≦N;
- (d) extracting M-bit number n from said d, said n with most significant bit aligned to yk with said k from step (c);
- (e) when said m is in the range 2i to 2i+1−1 for a positive integer i, define a number t=m2M−1+(M−i)2M−1+table [m] where table [ ]is a lookup table;
- (f) when said n is in the range 2j to 2j+1−1 for a positive integer j, define a number u=n2M−1−j+(j−1)2M−1+table[n];
- and
- (g) taking t−u as an approximation of log (d/c) whereby a reliability figure is approximated.
5 more elements
Dependencies are inferred from the claim text.