Communication system and method with orthogonal block encoding

• US 6,963,532 B1
• Filed: 11/07/2000
• Issued: 11/08/2005
• Est. Priority Date: 07/22/1997
• 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): Pham, Chi
• Assistant Examiner(s): Boakye, Alexander O.
• Application Number:
  US09/707,590
• Time in Patent Office: 1,827 Days
• Field of Search: 370/208, 370/342, 370/203, 370/209, 370/320, 370/335, 375/130, 375/137
• US Class Current: 370/208
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

A communication system and method with orthogonal, block encoding is provided. Encoded signals are transmitted by repeating transmissions of symbol blocks with a phase or sign change selected for each block from a sequence of phase or sign changes. Different symbols are transmitted using orthogonal sequences. The decoding uses different orthogonal sequences for separating the received encoded signals into corresponding separate channels. The orthogonal encoding is removed from the encoded transmitted signals and corresponding ones of the repeated symbols are added in successively received repeated blocks after the orthogonal encoding is removed. A transmitter uses a digital source encoder to encode information into symbols, and each symbol is repeated a preselected number of times to successively produce groups of repeated bits. Each repeat bit is changed in phase or sing by application of a sign or phase change determined by a selected assigned orthogonal code associated with the transmitter. The sign changed bits are interleaved from a number of such groups to successively generate a number of blocks, each composed of the different sign or phase changed bits of the preselected number of repeated groups and having a collective sign or phase change corresponding to a common sign change or phase shared by all bits of the block. The interleaved blocks then modulate a radio signal for transmission.

Claims

1. A method for communicating between a plurality of transmitters and a receiver, said method comprising:

orthogonally encoding information signals at each transmitter, said orthogonally encoding comprising;

coding information signals at said transmitter to produce corresponding information blocks containing coded information symbols;

repeating each information block a predetermined number of times according to a predetermined spectrum-spreading factor;

orthogonally encoding said repeated information blocks by applying a modification factor to each repeat of said information blocks, the sequence of modification factors applied to successive repeats of said information blocks forming one of a set of mutually orthogonal coding sequences; and

transmitting said orthogonally encoded information signals from said plurality of transmitters.

2. The method according to claim 1 further comprising decoding said orthogonally encoded information signals by employing different orthogonal codes respectively for separating the information blocks corresponding to different information signals into corresponding separate channels.

3. The method of claim 2 wherein decoding said orthogonally encoded information signals comprises removing orthogonal encoding from said encoded information blocks and adding corresponding ones of said information symbols in repeated information blocks.

4. The method according to claim 3 wherein removing said orthogonal encoding form said encoded information blocks comprises forming a summed signal for each symbol within the repeated information blocks and processing the summed signal with an equalizer.

5. The method of claim 1 wherein applying a modification factor to each repeat of said information blocks comprises imposing a sequence of phase changes onto said repeated information blocks.

6. The method of claim 1 wherein applying a modification factor to each repeat of said information blocks comprises imposing a sign change on said repeated information blocks.

7. A receiver to receive a transmitted signal comprising repeated information blocks that have been orthogonally encoded, said receiver comprising:

a receiver circuit to receive an orthogonally encoded information signal comprising at least one repeated information block; and

a decoder to decode said orthogonally encoded repeated information block, said decoder comprising;

an orthogonal code remover for removing the orthogonal encoding from said repeated information blocks; and

an adder for adding corresponding ones of said symbols in said repeated information blocks after the orthogonal encoding is removed by said orthogonal code remover to form a summed signal for each symbol within said repeated information blocks.