PR-QMF based codes for multipath/multiuser communications

Author

Hetling, Kenneth ; Saulnier, Gary ; Das, Pankaj

Author_Institution

Dept. of Electr. Comput. & Syst. Eng., Rensselaer Polytech. Inst., Troy, NY, USA

fYear

1995

fDate

13-17 Nov 1995

Firstpage

105

Lastpage

109

Abstract

One common type of interference in a mobile communications channel is multipath interference. Traditionally, the DSSS/CDMA systems utilize maximal length sequences (m-sequences) as the spreading codes. The m-sequences were chosen because they possess the desired randomness properties and are easily generated via shift registers. The perfect reconstruction quadrature mirror filter (PR-QMF) based spread spectrum codes were proposed as an alternative to the m-sequences. A class of spreading codes based on PR-QMF subband trees is examined. After developing the properties of these codes as they relate to the multipath and multiuser channels, objective and constraint functions are formulated which incorporate these properties. These functions are then used in a multivariable optimization problem to determine the PR-QMF coefficients for use in the subband tree structure. Once the subband tree is complete, the spreading codes can then be extracted for use. It is shown that in the limiting cases, the optimal solutions tend towards TDMA and FDMA like structures

Keywords

code division multiple access; filtering theory; land mobile radio; multipath channels; optimisation; pseudonoise codes; quadrature mirror filters; radiofrequency interference; signal reconstruction; spread spectrum communication; DSSS/CDMA systems; FDMA; PR-QMF based codes; PR-QMF coefficients; PR-QMF subband trees; TDMA; constraint functions; mobile communications channel; multipath channels; multipath interference; multiuser channels; multivariable optimization problem; objective functions; perfect reconstruction quadrature mirror filter; spread spectrum codes; spreading codes; subband tree structure; Code division multiaccess; Filtering; Land mobile radio interference; Multipath channels; Optimization methods; Pseudonoise coded communication; Quadrature mirror filters; Signal sampling/reconstruction;

fLanguage

English

Publisher

ieee

Conference_Titel

Global Telecommunications Conference, 1995. Conference record. Communication Theory Mini-Conference, GLOBECOM '95., IEEE

Print_ISBN

0-7803-2509-5

Type

conf

DOI

10.1109/CTMC.1995.502941

Filename

502941