Performance Analysis for Bit Error Rate of DS- CDMA SensorNe

TELKOMNIKA, Vol.10, No.1, March 2012, pp. 165~170

ISSN: 1693-6930

accredited by DGHE (DIKTI), Decree No: 51/Dikti/Kep/2010 165 Performance Analysis for Bit-Error-Rate of DS-CDMA

Sensor Network Systems with Source Coding

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1Ali M. Fadhil, Haider M. AlSabbagh*

2Department of Computer Engineering, College of Engineering, University of Basra, Basra, Iraq Department of Electrical Engineering, College of Engineering, University of Basra, Basra, Iraq

e-mail: ali_muayed@, haidermaw@

Abstrak

Salah satu teknik terkenal yg digunakan dengan jaringan sensor nirkabel untuk mengakses jaringan adalah memanfaatkan akses jamak pembagian sandi runtun langsung. Jumlah energi yang dikonsumsi dan antar pengguna masih dianggap sebagai masalah utama dengan menggunakan jaringan tersebut. Energi yang dikonsumsi dan interferensi meningkat ketika jumlah pengguna (penerima) meningkat. Penelitian ini dilakukan untuk menyelidiki pengaruh faktor mitigasi melalui analisis penyandian energi minimum yang mengeksploitasi bit redundan untuk menghemat listrik, dengan menggunakan link radio frekuensi dan modulasi on-off-keying. Faktor-faktor ini dianalisis dan dibahas untuk beberapa level galat yang diharapkan dengan memanfaatkan saluran, melalui laju galat bit dan rasio sinyal dan derau pada beberapa pengguna yang berbeda.

Kata kunci: DS-CDMA, laju galat bit, sensor nirkabel

Abstract

One of the distinguished techniques used with wireless sensor networks to access the network is utilizing direct sequence-code division multiple access. However, amount of consumed energy and multiple access interference are still considered as the main problems with employing such networks. The consumed energy and interference are rising when number of users (receivers) increases. Therefore, this paper is conducted to investigate mitigating influence these factors through analyzing the minimum energy coding which exploits redundant bits for saving power with employing radio frequency link and on-off-keying modulation. These factors are analyzed and discussed for several levels of expected errors in the utilizing channel, through the bit error rates and amount of signal to noise ratio for different number of users.

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Keywords: bit error rate, DS-CDMA, wireless sensors

1. Introduction

Recently, wireless sensor network applications are gaining much interest in academia and industry areas. The wireless sensor network technologies have been chosen as one of the most important technologies in the 21th century [1]. Sensor networks consist of hundreds to thousands of tiny sensor nodes that can sense data, process, and communicate with each other nods or data sink [2]. Designing the wireless sensor network is challenging due to high node density, frequent topology changes, limited battery and computing power and requirement of very low cost nodes [3]. Nodes of the sensor networks communicate with each other through wireless media. The multiple access is a serious problem due to high node density, so, the code division multiple access (CDMA) is a promising multiple access scheme for sensor and ad hoc network to its interference averaging properties’ [4]. The minimum energy (ME) coding combined with direct sequenceCDMA (DS-CDMA) is proposed to address both power saving and multiple access interference (MAI) problems [5, 6]. ME coding reduces the number of high bit (1 bit) by inserting redundant bits, which results increase in codeword length (bandwidth) with less high bit. Power saving can be achieved by using On-Off-Keying (OOK) because only the high bit is transmitted through the channel. As most of bits in a codeword are zeros the multiple access interference (MAI) is also significantly reduced. Thus, it allows nearby users to co-exist and substantially enhances the bit error rate (BER) performance and specify the (SNR) to number of the receivers (users).

Received December 1, 2011; Revised January 22, 2012; Accepted February 15, 2012