40 International Journal of Communication Networks and Information Security (IJCNIS) Vol. 8, No. 1, April 2016 Adoption Features and Approach for UWB Wireless Sensor Network based on Pilot Signal assisted MAC Kamran Ayub 1, 2 , Valerijs Zagurskis 2 1 Technology Group, NYUAD Saadiyat Campus New York University. 2 Institute of Electronics and Computer Science, Riga Technical University, Latvia. Kamran.ayub@nyu.edu, valerijs.zagurskis@rtu.lv Abstract: In the field of wireless sensor network (WSN), Pilot Assisted Transmission (PAT) is a new concept. In our previous research, a mac layer algorithm called, “PA-MAC” was designed, which exclusively uses PAT technique for the medium access control. The performance of PA-MAC was evaluated under multi- hop and single hop WSNs. It was excellent under a single hop structure (i.e. network with a few nodes). But when it was evaluated for the dense network topology, the performance seriously declined. It was noted that the two main reasons of performance degradation are interference and transmission range. Technically there are two ways to tackle a dense network traffic problem. One is to use the multi-hop structure and the other one is clustering. In this research paper, clustering based adoption strategy is examined, and beside dynamic clustering approach multiple optimization features (i.e., clustering formation based on transmission range, dynamic cluster head selection and use of the Volterra code for the mitigation of interference) are added and tested. Collectively these adoption features have not only improved the media access performance but also optimized the network lifetime. Keywords: Clustering, Energy efficiency, Media Access Control, Ultra wide band, Wireless Sensor Network. 1. Introduction PAT is a new concept in the field of wireless sensor network communication, due to its unique signal transmission structure, it has shown tremendous results when used for the mac layer in wireless sensor network. Earlier we had proposed one of the first medium access control algorithm “PA-MAC” based on PAT technique. That is, a schedule based MAC algorithm that uses impulse radio at the physical layer. One of the main job of a sensor network is to securely and smoothly transfer the sensed data to the sink. This can be achieved only if the underneath network formation is correct (i.e., cluster is properly formed). The root cause of performance degradation in a PA-MAC architecture is its nodes formation in a heavy network topology. The traditional clustering and optimization procedures could not resolve the performance issues [2], because of Transmitted Reference/Delay Hopped Impulse Radio (TR/DH IR-UWB) at radio layer. In this research paper we have targeted these main performance degradation blockages and successfully optimized network performance by applying multiple adoption features. The improved architecture focuses the transmission range and node formation and uses (the same) pilot signal assisted mac with impulse radio at Physical layer. Due to the complexities involved in a multi-hop technique clustering approach for the network formation is used here. It is known that when the number of clients increases in a WSN cluster the whole burden comes on the MAC layer [3], as a result collision and interference issues occur. Similarly selection of Cluster Head based (only) on residual energy can save the power but can create transmission and formation issues. As a solution for these challenges, our cluster formation is based on a transmission range rule, where groups are formed based on transmission range from the base station. Additionally, a threshold level is fixed for the cluster membership and the number of members for a cluster never crosses that limit. Beside this cluster head selection is based on multiple parameters called cost function. That selects the strongest node as cluster head. These two major enhancements not only simplifies the network formation but also improves the overall network performance. The rest of the research paper is divided as follows. Section 2 gives a brief overview of PA-MAC media access control algorithm. In section 3, a brief explanation of radio layer (Delay Hopped Transmitted Reference Scheme) is defined. Section 4 covers the clustering and proposed adoption features. In section 5 the network performance & simulation results are evaluated. The summary and conclusion are explained in Section 6. 2. Media Access Control Layer Use of PAT in WSN saves receiver’s energy and avoids channel estimation that is very attractive for the wireless sensor network [1], [2]. The main design of PA-MAC is based on two phases. Phase-1 is an initial phase which remains active unless the media access requests cross the threshold level. Right after the 1st collision (due to media access requests) control transfers to Phase-2. Phase 2 deals with different bottlenecks through prioritization and scheduling. See table 1 based on main steps of PA-MAC algorithm [1]. Table 1. Main steps of PA-MAC algorithm. (Phase1) Step1 //FCFS- No Synchronization- low activity For ( i = 1 to n) //All nodes will set Tp to Tmax Tp(n(i))=Tmax; While( Tp≠0) //During Priority time Node State= Rx //{Listen only while Tp} Step2 // After Tp (Priority Time) Node State = Tx(Pilot) // If interested for Tx If Media≠ IDLE //If media is not idle - //Collision Go to Phase 2 //Synchronize and Prioritize //the communication Else //Continue till collision Node State= Tx(data) i++ ; // Next node