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Optimal Receiver Pulse Shaping Filter Design for IS-2000 CDMA Systems

IP.com Disclosure Number: IPCOM000006770D
Original Publication Date: 2002-Jan-30
Included in the Prior Art Database: 2002-Jan-30
Document File: 9 page(s) / 254K

Publishing Venue

Motorola

Related People

Fan Wang: AUTHOR [+3]

Abstract

In CDMA systems (IS-95, IS-2000, etc.), the transmitter pulse shaping filter is a 48-tap FIR filter (known as IS-95 filter) defined in the standards. The received signal using the matched receiver filter has a signal to inter symbol interference ratio (SIR) around 16 dB. In 3G and beyond 3G CDMA systems (1XEV-DO, 1XEV-DV, etc.), higher SIR of the received signal is required so that high order modulation methods can be applied to achieve high data transmission speed. In this paper, we propose a method to design receiver pulse shaping filters for CDMA systems, such that the signal to interference plus noise ratio (SINR) of the received signal is maximized. Numerical examples show that the receiver filters designed using our method can significantly reduce the interference in comparing to the matched receiver filter. Moreover, receiver filters having less taps and higher SIR than the matched filter can be designed using our method. The shorter receiver filters will reduce the power consumption of the mobile units.

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Page 1 of 9

Optimal Receiver Pulse Shaping Filter Design for IS-2000 CDMA Systems

Fan Wang and Jason Chen and Gregory Agami

Advanced Radio Technology Group, GTSS Motorola Inc. IL27-3G6, 1421 W. Shure Dr.

Arlington Heights, IL 60004

September 30, 2000

Abstract

  In CDMA systems (IS-95, IS-2000, etc.), the transmitter pulse shaping lter is a 48-tap FIR lter (known as IS-95 lter) dened in the standards. The received signal using the matched receiver lter has a signal to inter symbol interference ratio (SIR) around 16 dB. In 3G and beyond3GCDMA systems (1XEV-DO, 1XEV-DV, etc.), higher SIR of the received signal is required so that high order modulation methods can be applied to achieve high data transmission speed. In this paper, we propose a method to design receiver pulse shaping lters for CDMA systems, such that the signal to interference plus noise ratio (SINR) of the received signal is maximized. Numerical examples show that the receiver lters designed using our method can signicantly reduce the interference in comparing to the matched receiver lter. Moreover, receiver lters having less taps and higher SIR than the matched lter can be designed using our method. The shorter receiver lters will reduce the power consumption of the mobile units.

1 Introduction

In wireless communication systems, digital information symbols are transmitted in a form of analog waveforms through the wireless channel. The analog waveforms are the output of transmitter lters, which include pulse shaping lter, phase equalizer, and RF lters. On the receiver side, the received waveforms are rst sampled at multiple chip rates, and then ltered by receiver pulse shaping lter. The output of the receiver pulse shaping lter is down sampled to chip rate, and then sent into demodulator to recover the transmitted information. This communication link is shown in Figure 1.

  When the channel is an AWGN channel, the root Nyquist transmitter pulse shaping lter and its matched receiver lter can transmit information symbols without any inter symbol interfer- ence. In [4, 7, 5, 10], methods based on convex optimization are proposed to design general FIR transmitter pulse shaping lters that have such orthogonality property as the root Nyquist lter.

  However in commercial CDMA systems, the transmitter pulse shaping lter has been dened by the standards. In CDMA standards and standard proposals (IS-95, IS-2000, 1XEV-DO, 1XEV- DV, etc.), the transmitter pulse shaping lter is a 48-tap FIR lter (known as IS-95 lter). The signal to inter symbol interference ratio (SIR) of the received signal using the matched receiver

Corresponding author. Email: fanw@cig.mot.com. Tel: (847)632-4493. Fax: (847)632-3630.

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Receiver Pulse Shaping Filter Design for CDMA Systems Wang{Chen{Agami

lter is 16.5532 dB. If we have other lters (for example phase equalizer, RF lter, etc.) in the communication link, the SIR can be even lower.

  In new CDMA standar...