OFDM SYMBOL DIVERSITY COMBINER FOR BURST INTERFERENCE MITIGATION

• US 20120317465A1
• Filed: 06/01/2012
• Published: 12/13/2012
• Est. Priority Date: 06/08/2011
• Status: Active Grant

• Current Assignee: Vislink Technologies, Inc.
• Original Assignee: xG Technology, Inc.
• Inventors: ALAPURANEN, PERTTI
• Granted Patent: US 8,775,907 B2
• Time in Patent Office: Days
• US Class Current: 714/807
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit
• CPC Class Codes: H03M 13/1102 Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
• CPC Class Codes: H03M 13/2906 using block codes H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/2933 using a block and a convolutional code H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/41 using the Viterbi algorithm or Viterbi processors
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence

Abstract

The invention disclosed in this application describes a diversity combiner that operates as a maximal ratio combiner (MRC) when no interference is detected and as a selection combiner when OFDM symbol errors are detected with high probability.

Claims

1. A method of receiving and decoding a redundant OFDM transmission having packet A and packet B where both whole packets have failed decoding by using an interference mitigation selection combiner method wherein for each OFDM symbol the soft bits produced from the symbols are identified and combined according to the following method comprising:

first identifying both packet A'"'"'s and packet B'"'"'s individual OFDM symbols as packet A_n'"'"'s and packet B_n'"'"'s OFDM symbols with n indicating a symbol number from n=0 to n=N and where N=total number of symbols −

1;

next using an OFDM symbol error detection method to generate an OFDM symbol metric for interference burst errors for each OFDM symbol and comparing said OFDM symbol metric to a determined threshold to indicate if an OFDM symbol contains bit errors;

then if both packet A_n'"'"'s and packet B_n'"'"'s OFDM symbols have an OFDM symbol metric exceeding a threshold the soft bits produced from said packet A_n'"'"'s and packet B_n'"'"'s OFDM symbols are added together weighted by said OFDM symbol metric and selected to be decoded;

then if packet A_n'"'"'s OFDM symbol exceeds a threshold but packet B_n'"'"'s OFDM symbol does not exceed a threshold soft bits from packet B_n'"'"'s OFDM symbols are selected to be decoded;

then if packet B_n'"'"'s OFDM symbol exceeds a threshold but packet A_n'"'"'s OFCM symbol does not exceed a threshold packet soft bits from A_n'"'"'s OFDM symbol are selected to be decoded;

then if both packet A_n'"'"'s OFDM symbol and packet B_n'"'"'s OFDM symbol are below a threshold soft bits produced from both packet A_n'"'"'s OFDM symbol and packet B_n'"'"'s OFDM symbol are added as a function of the probability produced by the OFDM symbol estimation method and processed using a maximal ratio combiner and then selected to be decoded; and

,

final error decoding of said selected soft bits.

2. The method of claim 1 wherein if said final error decoding fails then said determined threshold level is increased in predetermined increments and repeating said increasing until a predetermined maximum threshold level is met or the decoding is successful.