INTERNATIONAL JOURNAL OF ELECTRONICS ANDInternational Journal of Electronics and Communication Engineering & Technology (I...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 097...
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Effect of relay location on two way df and af relay in lte-a cellular networks

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Effect of relay location on two way df and af relay in lte-a cellular networks

  1. 1. INTERNATIONAL JOURNAL OF ELECTRONICS ANDInternational Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)ISSN 0976 – 6464(Print)ISSN 0976 – 6472(Online)Volume 3, Issue 2, July- September (2012), pp. 385-399 IJECET© IAEME: www.iaeme.com/ijecet.htmlJournal Impact Factor (2012): 3.5930 (Calculated by GISI) ©IAEMEwww.jifactor.com EFFECT OF RELAY LOCATION ON TWO-WAY DF AND AF RELAY IN LTE-A CELLULAR NETWORKS Jaafar Adhab Aldhaibani1, A. Yahya2, R.B. Ahmad3, N. A. Al-Shareefi 4, M. K. Salman5 1 School of Computer and Communication Engineering, University Malaysia Perlis (UniMAP), 01000 Perlis, Malaysia 2 School of Computer and Communication Engineering, University Malaysia Perlis (UniMAP), 02000 Perlis, Malaysia 3 School of Computer and Communication Engineering, University Malaysia Perlis (UniMAP) 01000, Perlis, Malaysia 4,5 School of Computer and Communication Engineering, University Malaysia Perlis (UniMAP), Penang, Malaysia Email: Jaafar Adhab Aldaibani_- jaffar_athab@yahoo.com ; A.Yahya -abidusm@gmail.com; .R.B.Amad - badli@unimap.edu.my ;M.K.Salman- mohammedsalman03@yahoo.com ;ABSTRACTWireless multi-hop relay systems are important technologies in mobile communications. Thesesystems ensure high-speed data transfer and extended coverage area at a low cost. This paperinvestigates the position of a relay problem for the maximum capacity enhancement of a two-way Relay Node (RN) to achieve an efficient and scalable Long Term Evolution-Advanced(LTE-A) wireless network design. The performance of a multi-hop relay network at an optimumposition as well as a proposed half-duplex mode with two scenarios is investigated. A single RNfor Amplify and Forward (AF) relay is proposed in the first scenario, whereas a Decode andForward (DF) relay with a multi-hop LTE-A network is proposed in the second scenario. Theperformance of each scenario is analyzed. The optimum relay position that provides themaximum achievable rate with two-way performance is derived. The numerical results describethe optimum location of AF relay, which is 0.72 of the cell coverage radius, whereas the DFrelay achieves a maximum bit rate when the relay location is at 0.52 from the cell coverageradius.Keywords: LTE-A, AF relay, DF relay, UE, half-duplex 385
  2. 2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME1. INTRODUCTION Long-term evolution-advanced (LTE-A) is the successor of the third-generation partnershipproject (3GPP) LTE, which is expected to improve LTE features in terms of coverage andthroughput [1]. Relay is one of the primary innovations of LTE-A. This innovation increases thecell-edge coverage radius and throughput as well as enhances the usage efficiency of networkresources. The basic idea of relay is to forward signals through one or more relay nodes (RNs)before retransmitting to the destination node. This process is in contrast to traditional protocolswherein the base station (BS) directly sends signals to user equipment (UE). The relay structure adds RNs to the network architecture and enables trafficsignaling/forwarding between the UE and the BS to expand the coverage around cell edges,especially in high-shadowing environments. The relay structure also increases hotspot capacity,as shown in Figure 1. [2]. Fig. (1) Relaying scenariosResearchers are looking for ways to improve network throughput and coverage due to thedemand for mobile, Internet, and wireless multimedia applications, and the requirements forfuture 4G systems Studies on relay location are important to achieve maximum bit rate.Establishing coverage areas with low-cost resources is the first step to meet these aims. As such,low-cost RNs are being deployed in each cell of next-generation cellular systems. The RN enhances the cell radius because it is closer to the cell-edge UE than to the BS.Furthermore, RN improves the received signal-to-noise ratio (SNR) to the UE. The infrastructurecost of distributing to more BSs is reduced because the cell radius is increased. The RN is wirelessly connected to the radio access network via a donor cell, which is connectedto the donor BS by a relay link. The UE is connected to the RN via the access link, as shown inFigure 1. The two-hop communication between the BS and the UE units through the RN can befacilitated by different relay transmission schemes. The relay can be categorized in two typesdepending on its function.Amplify and Forward (AF): This type of relay works as a repeater, wherein the RN receives thesignals from the BS or the UE and then amplifies this signal and forwards it to the UE or to theBS. AF relays are simple and have short delays. However, such relays are beneficial in most 386
  3. 3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEMEnoise-limited system deployments because they amplify the interference and the noise along withthe desired signal, as shown in Figure 2a. [3, 4].Decode and forward (DF): DF relays receive and encode the desired signal, and then forward anew signal [2]. The processing delay in DF relay is relatively long. However, this type of relay isemployed in interference-limited environments. In such environments, this class of relays doesnot amplify noise and interference, such as in the case of the AF relay shown in Figure 2b [3,4]. Transmitted signal BS Received signal RN Power UE Amplification (a) AF relay BS RN Demodulation Encoding Power UE /decoding /modulation Amplification (b) DF relay Fig. (1) Types of relay nodesIn this paper, we propose a half-duplex for two relay types to determine the optimum location ofAF and DF relays where all nodes are fixed.This paper analyzes two-way AF and DF relays with the optimum location problem to achieve ahigh rate of data transfer in an LTE-A network. The remainder of this paper is organized as follows: Section 2 presents the proposed systemmode. Section 3 describes the first scenario of two-way AF and DF relay performance. Section 4introduces the optimum relay location. Section 5 discusses the results of the proposed model, andSection 6 concludes this paper. 387
  4. 4. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME2 . System model Figure 3. shows that the proposed system contains three wireless nodes: a source BS, a relayRN, and a UE with the received signal Y = BX + n (1)where X is the transmitted symbol from BS, B is the coefficient channel between the source andthe destination, and n is the Additive White Gaussian Noise (AWGN) in the correspondingchannels with variance N Ο , i.e., n ~ CN (0, N Ο ) [5]. Fig (2) Three nodes relay scheme2.1. AF-Relay In the first scenario, the RN acts as an AF scheme. The suggested system operates in a half-duplex mode, where the relay cannot simultaneously transmit and receive, as shown in Figure 2.The relay receives information from the BS and the UE in time slot [ t1 ]. The received signal,yRN [t1 ] , can be written as yRN [t1 ] = Pt B BS −RN X [t1 ] + Pu B RN −UE X [t1 ] + n RN (2)where, Pt , Pu is the transmitted power for the BS and the UE, and n RN is the AWGN withvariance N Ο . The received signal at UE from BS via a direct link is given by 388
  5. 5. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME y UE [t 1 ] = Pt B BS −UE X [t 1 ] + nUE [t 1 ] (3) The BS and UE at the second time slot [ t 2 ] receive the amplified signals transmitted from RN,X RN [t 2 ] , with amplification factor η [6]. The uplink (UL) and downlink (DL) transmittedsignals from the RN to the BS and to the UE can be represented as yBS[t 2 ] =ηB BS −RN yRN[t1] + nBS (4) y U E [t 2 ] = η B R N −U E y R N [t 1 ] + nU E (5) PRN (6) η = PBS | B BS −RN | + PUE | B RN −UE |2 + N Ο 2 The maximum radio combiner (MRC) at the UL from the RN and UE to the BS can then berepresented as y BS[t 2 ] = η  B BS − RN y RN [t1] + PUE B R N −UE X [t 1 ] + n R N  + n BS   (7)   By substituting (2) into (7), we obtain yMRC[t 2 ] = PUE B BS −UE X [t1 ] + n BS + (η B BS −RN B BS −RN X [t1 ]) + η B BS −RN B RN −UE X [t1 ] +η B BS −RN n RN BC Direct link Relay link The MRC at the DL from the relay and direct links to the UE can be represented as y MRC [t 2 ] = Pt B BS −UE X [t 2 ] + η B RN −UE y RN [t 1 ] + nUE UE (8)By substituting (2) into (8), we obtain y MRC [t 2 ] = UE Pt B BS −UE X [t 2 ] + η B BS − R N B RN −UE X [t 2 ] + (η B RN −UE B R N −UE X [t 2 ] ) + η B RN −UE n R N + nUEwhere n BS and n UE are the AWGNs with variance N Ο at the BS and UE, respectively. 389
  6. 6. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME Each source node processes and then cancels the self-interface term from the received signal[7,8]. Therefore, the resulting signals at the BS and UE after self-interface cancelation can berewritten as ) MRC y BS [t 2 ] = PUE B BS −UE X [t 1 ] + η B BS − RN B RN −UE X [t 1 ] + η B BS −RN n RN + n BS (9) ) y [t 2 ] = Pt B BS −UE X [t 2 ] +ηB BS −RN B RN −UE X [t 2 ] +η B RN −UE nRN + nUE MRC UE (10)Assuming that the AWGNs at all sources are equal (n RN =n BS =nUEq = N o ) , the instantaneousSNR can be evaluated in two ways AF PBS | B BS −UE |2 η 2 | B BS −RN |2| B RN −UE |2 (11) ρBS 2UE = + 2 NΟ ( η | B RN −UE |2 +1 N Ο ) PUE | B BS −UE |2 η 2 | B BS −RN |2| B RN −UE |2 (12) AF ρUE 2BS = + NΟ ( ) η 2 | B BS −RN |2 +1 N Ο Direct link Relay linkThe achievable bit rates of the multi-hop node at each DL and UL is represented as R DL = 1 log 2 (1 + ρ BS 2UE ) AF 2 (13) RUL = 1 log 2 (1 + ρUE 2BS ) AF 2 (14)2.2 . DF relayA DF relay with a half-duplex mode is proposed in the second scenario. In time slot [ t1 ], therelay receives signal the BS and the UE. The received signal, yRN [t1 ] , can be written as yDF [t1] = Pt B RN −UE X [t1] + n RN + PUE B BS −UE X [t1] + nUE (15) RNThe received signal at the UE from the BS via a direct link is 390
  7. 7. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME yDF[t1] = Pt B BS −UE X [t1] + nUE [t1] UE (16) At the second slot [ t 2 ] the relay broadcasts the received signal to the BS and UE after signalprocessing. The UE will combine the two signals from the direct and relay links as indicated inthe following: yDF [t1] = ξ PRN B RN −UE X [t 2 ] + n RN + Pt B BS −UE X [t 2 ] + nUE UE (17) The factor ξ in (17) enables the two received modes to be considered at the destination UE,where, if ξ =1, the MRC for signals at the UE are received with the second time slot. However,if ξ =0, only the UE receives the signal from the source with the first time slot. The SNR for each hop from Equations (15), (16), (17) can be clarified as Pt | B BS −UE |2 ρBS −UE = (18) No Pt | B BS −RN |2 ρBS −RN = (19) No PRN | B RN −UE |2 ρRN −UE = (20) No The SNR is affected by the channel environment including the distance between the transmitterand receiver, the fading state of the channel, and noise and interference [9]. Thus, as shown inTable I, the channel coefficient between the source (i) and the destination (j) can be defined as 2 B i − j = (d i − j )−α (21)where d i − j is the distance between the source and the destination. The the path-loss exponent isdenoted by α (typically ∈ {2 − 5}) , which is dependent on the environment [10, 12]. 391
  8. 8. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME Table I Two-way transmission /reception link Transmitter (i) Receiver (j) BS UE RN RN UE BS UE RN BS Tx. Time Rx. TimeThe achievable rate for the destination node with DF relay is DF { DF R UE = min R UE (1), R UE (2) DF } (22) DF 1 RUE (1) = log 2 (1 + θρBS −UE ) (23) 2   RUE (2) = 1 log 2  ρ B S −UE + ρ R N −UE + 2 (1 − θ ) ρ B S −UE ρ R N −UE DF  2  No    (24) The power allocation ratio at the source node is allocated by θ , which controls the amount ofcorrelation between the signals X [t1 ] and X [t 2 ] , where θ ∈ (0,1) [11,13]. By using Equations(18), (19), (20), we can rewrite (24) as DF 1 RUE (2) = log 2 ( A + B ) (25) 2 Pt PRN 2 Pt PRN A= −α + −α ; B = (1 − θ ) −α −α N o d BS −UE N o d RN −UE No d BS −UE d BS −UE 392
  9. 9. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME3. OPTIMUM POSITION OF RELAY This section formulates the optimization problem of a single RN location for multi-hopnetwork. Figure 3. shows that the system is formulated as a simple three-node relay model witha single source and destination. Fig.(3) Scheme of optimal relay locationGiven the location of the source and destination, along with the transmission power of thesource and the relay, the objective is to determine the optimal position of the relay to achieve themaximum data rate at the destination using a specific cooperative relay scheme (i.e., AF or DF).The received power decreases as the distance between the transmitter and the receiver increases.Thus, the optimal position of the relay must be on the line that passes through the source anddestination, as shown in Figure. 4 [14].Assuming that the reference distance between the source and the destination is a fixed value andthat the relay is located between the source and the destination, d BS −RN = qd BS −UE , q ∈ (0,1) . Then,d RN −UE = (1 − q )d BS −UE . The process of determining the optimal position of relay for AF and DFrelays based on (11) and (12) is as follows: −α −α AF P d −α η 2 (qd BS −UE ) ( (1 − q )d BS −UE ) (26) ρ BS 2UE = BS BS −UE + NΟ η 2 (1 − q )d −α   ( BS −UE ) + 1 N Ο   −α −α PUE d BS −UE η (qd BS −UE ) ( (1 − q )d BS −UE ) −α 2 AF (27) ρ UE 2 BS = + NΟ  2 −α  η qd   ( BS −UE ) +1 N Ο The procedure is the same for the DF relay in (25) 393
  10. 10. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME DF 1 ˆ ˆ RUE (2) = log 2 A + B 2 ( ) Pt PRN ,B= 2 ˆ Pt PRN ˆ A= −α + −α (1 − θ ) −α −α N o d BS −UE N o ( (1 − q )d BS −UE ) No d BS −UE ( (1 − q )d BS −UE )4. RESULTS AND DISCUSSIONThis section presents the numerical results of the two scenarios of the AF and DF relays.These performances are analyzed and derived in Section (3). Figure 5. shows the bit rate atthe DL versus the SNR at the direct and multi-hop links. The multi-hop link enhanced andincreased the bit rate and SNR at the Dl. For example, the bit rate was enhanced to 0.33 at40 dB SNR. The comparison between two scenarios shows that the amplification signal for AF relayprovides better bit rate enhancement than the DF relay for the same RN-transmitted powerregardless of interference. All results in this paper change with the relay location of the BS.Figure 6. shows that change in the distances between the nodes facilitates changes in thepath-loss effect and in the channel environment. Figure 7. explains the performance of the AF relay with a two-way UL and DL. Relaylocation is affected by two-way bit rate, wherein the power of the UE is smaller than thepowers of the RN and BS, and the RN and BS have numerous and larger antennas than theUE. The optimum location for AF relay in this case is 0.72 from the coverage radius of thecell at the DL and UL. The optimum location for DF relay is 0.52 from the coverage cellradius because the AF relay amplifies the received signal. Figure 7. shows that the locationsfor the two relay strategies provide the maximum achievable rate.The DF relay behavior changes at the relay link when the power allocation is increased from θto (0, 1), where θ controls the correlation between the power signals at the relay link (Figure 8.). 394
  11. 11. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME5. CONCLUSION The relay location problem that provides the maximum achievable capacity in LTE-A wirelessnetworks was determined in this paper. The contributions of this work are as follows: First, wederived the SNR and the bit rate for two-way UL and DL. A new route selection strategy issuggested. Second, we performed optimization design for relay location to maximize the bit rate.The correct design of relay location can significantly improve system capacity. However,deploying the RS at random locations may degrade the cell resource allocation for both AF andDF. The numerical results of this paper provide a data reference for network designers inobtaining the best bit rate when selecting relay locations. 6 Direct Link 5 Multi-hop Link AF Relay Bit Rate (bit/s/Hz) 4 3 2 1 0 0 10 20 30 40 50 60 70 SNR(dB) Figure 5. Bit rate and SNR enhancements between the direct and relay links 395
  12. 12. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME 6 DF Relay 5 W RN power AF Relay 5 W RN power 5.5 10 W RN Tx power 5 4.5 Rate bps/Hz 4 3.5 3 2.5 2 1.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Normalized q (d /R) rn Fig. (6) The optimum position for DF and AF relay 7.4 Down link 7.2 Up Link 7 6.8 Rate bps/Hz 6.6 6.4 6.2 6 5.8 5.6 5.4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Normalized q (d /R) rn Figure 7. The optimum position for DF and AF relay 396
  13. 13. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME 3.6 DF Relay 5 W O=0.2 3.4 DF Relay 5 W O=0.2 DF Rlay 5 W O=0.6 DF Rlay 5 W O=0.7 3.2 DF Rlay 5 W O=0.9 3 Rate bps/Hz 2.8 2.6 2.4 2.2 2 1.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Normalized q (d /R) rn Figure 8. The optimum position for DF with different power allocation ( θ )REFERENCES1. 3GPP TR 36.913 v8.0.0, (2008) “Requirements for Further Advancements for E-UTRA (LTE-Advanced)” Jun.2.Wantuan Luo, Ruiqiang Zhang and Xuming Fang (2012) “A CoMP soft handover scheme for LTE systems in high speed railway” EURASIP Journal on Wireless Communications and Networking,:1963. J. Parikh, A. Basu (2011) “LTE Advanced: The 4G Mobile Broadband Technology” International Journal of Computer Applications, January vol. 13– No.5, pp 0975 – 88874. J. A. AL-Dhaibani, A. Yahya, (2012) “Performance Enhancement of LTE-A, a Multi-Hop Relay Node, by Employing Half-Duplex Mode” IJCSI, May Vol. 9, Issue 3, No 35. R. U. Nabar (2004) “Fading Relay Channels: Performance Limits and Space–Time Signal Design” IEEE Journal On Selected Areas In Communications, August vol. 22, No. 66. M. Pischella, D. Le Ruyet (2011) “Optimal Power Allocation for the Two-Way Relay Channel with Data Rate Fairness” IEEE Communications Letters, September Vol. 15, No. 9.7. P. Rattanawichai and C. Pirak (2011) “ Implementation of Self Interference Cancellation for WCDMA Repeater” International Conference on Circuits, System and Simulation IPCSIT vol.7.8. E. Everett, D. Dash, C. Dick , A. Sabharwal (2011) “ Self-Interference Cancellation in Multi- hopFull-Duplex Networks via Structured Signaling” Forty-Ninth Annual Allerton Conference Allerton House, UIUC, Illinois, USA, September,9. J. Parikh, A. Basu (2011) “LTE Advanced: The 4G Mobile Broadband Technology” International Journal of Computer Applications, January vol. 13– No.5, pp 0975 – 8887. 397
  14. 14. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME10. B. Lin, P. Han Ho, L. Liang Xie (2008) “ Relay Station Placement in IEEE 802.16j Dual- Relay MMR Networks” IEEE International Conference, pp 3437 - 3441.11. S. Sesia, I.Toufik, M. Baker (2011) “LTE – The UMTS Long Term Evolution from Theory to Practice” A John Wiley & Sons, Ltd., Publication, Second Edition pp. 68012. Z. Ding, Kin K. Leung, (2011) “Cross-Layer Routing Using Cooperative Transmission in Vehicular Ad-hoc Networks” IEEE Journal On Selected Areas In Communications, March, Vol. 29, No. 313. A. Høst-Madsen, J. Zhang, (2005) “Capacity Bounds and Power Allocation for Wireless Relay Channels”. IEEE Transactions on Information Theory, Vol. 51, No. 6, June.14. G. Joshi, A. Karandikar (2011) “Optimal relay placement for cellular coverage extension” International conference IEEEAUTHOR BIOGRAPHY Jaafar Adhab Al-Dhaibani earned his B.Sc. degree in Electrical and Electronic Engineering, major in Telecommunications, from the University of Technology, Baghdad, Iraq and earned his M.Sc. degree in Wireless Communications in 2002 from the University of Technology, Baghdad, Iraq. Engr. Adhab worked with the Motorola Company (AIEE)as a field engineer and a system engineer for communication from 2005 to 2011. He alsoworked with ATDI Company for RF planning communication sites (IC telecom software). Hisresearches interest is in wireless communication focusing on long term evolution (LTE-A),fourth generation (4G), Cooperative communications .Now, he is studying to earn his Ph.D.degree in the Computer and Communication School of Engineering, University Malaysia Perlis(UniMAP). Abid Yahya earned his B.Sc. degree in Electrical and Electronic Engineering, major in Telecommunications, from the University of Engineering and Technology. Peshawar, Pakistan. Dr. Yahya began his career on a path that is rare among other research executives. He earned his M.Sc. and Ph.D. degrees in Wireless and Mobile systems in 2007 and 2010, respectively, from the Universiti Sains Malaysia, Malaysia. Currently, he is working in the School of Computer and Communication Engineering, Universiti Malaysia Perlis (UniMAP). His professional career outside the academia includes writing for international magazines and 398
  15. 15. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 2, July-September (2012), © IAEME newspapers as a freelance journalist. He employed this combination of practical and academic experiences to a variety of consultancies for major corporations. R.B. Ahmed obtained his B. Eng in Electrical and Electronic Engineering from Glasgow University in 1994. He obtained his M.Sc and Ph.D. in 1995 and 2000, respectively, from the University of Strathclyde, UK. His research interests are on computer and telecommunication network modeling using discrete event simulators, optical networking, and coding and embedded system based on GNU/Linux for vision. He has five (5) years of teaching experience in Universiti Sains Malaysia. Since 2004, he has been working in Universiti Malaysia Perlis (UniMAP), where he is currently the Dean in the School of Computer and Communication Engineering and the Head of the Embedded Computing Research Cluster. Nael Ahmed Al-Shareefi received the B.Sc. degree in electronic and communications engineering and the M.Sc. degree in communications engineering from University of Technology, Baghdad, Iraq, in 1999 and 2001 respectively. He is currently a Ph.D. communication engineering studentat University Malaysia Perlis (UniMAP), school of computer and communicationengineering. He has working experience as a Microsoft System Engineer . His researchinterest’s are in radio-over-fiber systems, and computer networks communications. M. K. Salman, he received his MSc degrees in Electrical and Computer Engineering from University of Technology in 2004. He was working as project manager in IT Company. His research interests focus on network deployment and wireless communication with emphasis on WiMAX networks. Now, he is studying to earn his Ph.D. degree in the Computer andCommunication School of Engineering, University Malaysia Perlis (UniMAP). 399

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