Patent Number: 6,310,869

Title: Method and apparatus for reducing amplitude variations and interference in communication signals, such as in wireless communication signals employing inserted pilot symbols

Abstract: Several methods and corresponding apparatus reduce peak to average power in signals transmitted in a wireless communications system, particularly with respect to pilot symbols transmitted from a base station to several user stations. A large peak to average amplitude of inserted pilot symbols has been found to result from a common sign chip position that exists in orthogonal codes, such as Walsh codes. In a first embodiment, the Walsh codes are multiplied by a random value of .+-.1. Under a second embodiment, the common sign chip position is eliminated in each Walsh code. The user station then inserts the missing chip position to regain orthogonality. In a third embodiment, the base station transmits pilot symbols, on a separate pilot channel, in only symbol positions that user stations expect to find pilot symbols. Under a fourth embodiment, each Walsh code is randomly shifted.

Inventors: Holtzman; Jack (San Diego, CA), Terasawa; Daisuke (San Diego, CA), Razoumov; Leonid (San Diego, CA)

Assignee: Qualcomm Incorporated

International Classification: H04B 7/005 (20060101); H04J 11/00 (20060101); H04B 1/707 (20060101); H04J 013/00 ()

Expiration Date: 10/30/2018