Method and apparatus for transmission and reception within an OFDM communication system

• US 7,535,967 B2
• Filed: 05/02/2007
• Issued: 05/19/2009
• Est. Priority Date: 10/17/2003
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Baum, Kevin L., Nangia, Vijay, Krauss, Thomas P.
• Primary Examiner(s): Corrielus; Jean B
• Application Number:
  US11/743,186
• Publication Number:
  US 20070201572A1
• Time in Patent Office: 748 Days
• Field of Search: 375/130, 375/140, 375146-147, 375/224, 375/340, 375/297, 375/295, 375/260, 370/206, 370/491, 370/500, 455/69, 455/522
• US Class Current: 375/260
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0232 by interpolation between sounding signals
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26134 Pilot insertion in the transmitter chain, e.g. pilot overlapping with data, insertion in time or frequency domain
• CPC Class Codes: H04L 5/0021 in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions

Abstract

In an OFDM system the same Walsh code is used at the same time for a plurality of transmitters. The multiple transmitters can be from the same, or different devices (e.g., different base stations on the downlink, different terminals on the uplink). Each subcarrier/antenna combination will share a similar pilot Walsh code, except for the fact that the scrambled spread pilot signals will be phase shifted on some subcarriers of some antennas, based on the subcarrier/antenna combination.

Claims

1. A system comprising:

a first multicarrier transmitter outputting a first spread pilot signal to a receiver, the first spread pilot signal being spread over a first spreading block interval on a first plurality of subcarriers; and

a second multicarrier transmitter outputting a second spread pilot signal to the receiver on the first plurality of subcarriers within the spreading block interval, wherein for each of the plurality of subcarriers, the second spread pilot signal differs from the first pilot signal by a predetermined phase amount.

2. The system of claim 1 wherein the predetermined phase amount is equal to a constant value multiplied by an integer.

3. The system of claim 1 wherein the predetermined phase amount is equal to a constant value multiplied by a subcarrier index.