Need of Power Allocation in Cooperative Mesh Netwrok

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1 Need of Power Allocation in Cooperative Mesh Netwrok 1 Shital G. Ramane, 2 Dattatray S. Bade 1 Electronics and Telecommunication Department, Alamuri Ratnamala Institute of Engineering and Technology Shahapur, India 2 Electronics and telecommunication Vidyalankar Institute of Technology Wadala, India. Abstract Wireless communication has emerged as one of the largest sectors of the telecommunications industry. The next generation wireless network calls for much complex interactions in network, where the involved nodes cooperate with one another in order to improve performance their own communication which ultimately strengthen to global network. It gives rise to Cooperative communication system which achieves diversity through spatially separated nodes referred as relays, which are battery power. Cooperation takes place when source to destination communication get improved with the assistance of relay. The objective of this paper is to design an efficient algorithm to minimize the total consumed power of the network while guaranteeing transmission reliability of multiple active transmission pairs through cooperative wireless communications. We present a novel energy allocation scheme for multiple relay nodes that results in efficient cooperative multiple-input multipleoutput (MIMO) communication. Keywords MIMO, cooperative communication, cooperative mesh network, power allocation. I. INTRODUCTION In recent decades, the world has going through big changes in Business area. As result of this wireless communication become one of the greatest sectors in Telecommunication Industry. Now in this industry point to point or point to multipoint communication is applied, for development in communication technology this paradigm of classical cellular networks has to be upgraded and new paradigms will be based on complex interactions with cooperating operation between nodes. It help to improve performance of own communication and also that of the global network. Cooperative Communication based on relaying nodes has promising approach to increase spectral and power efficiency, network coverage, and to reduce outage probability [2]. In cooperative communication system, by properly coordinating different spatially distributed nodes in a wireless system, one can effectively synthesize a virtual antenna array that emulates the operation of a multiantenna transceiver. Cooperative communications has many open problems. One of the major issues is to deal with quality assurance of given service, In order to provide a certain quality of service high bit rates with good performance is todays need. The objective of this special issue is: to advance in the understanding of cooperative transmission and to explore practical limitations of realistic cooperative systems. There are several ways to increase the bit rate of a digital communication system. One can go for a shorter symbol duration T. As the bandwidth is determine by the symbol rate 1/T there will be larger fraction of the frequency spectrum occupation. Such Bandwidth expansion is not beneficial because frequency spectrum is a valuable resource. Additionally shorter symbol duration also tends to increase degree of intersymbol interference which may affect to performance of the system. Another method to enhance the bit rate of a digital communication system is to use higher-order modulation schemes transmitting more than one bit per data symbol which results in a higher bit rate without bandwidth expansion. At the end of the 1990s, multipleantenna techniques were shown to provide a novel means to achieve both higher bit rates and smaller error rates. By using multiple antennas at transmitter and receiver, known as Multiple Input and Multiple out (MIMO), we can exploit diversity and multiplexing gain. [1]. The systems which get affected by slow fading and shadowing expected to get significantly improve by the application of cooperative diversity. Cooperative diversity is a cooperative multiple antenna technique for maximizing total network for any given sets of bandwidths. These diversity techniques can also be used to enhance bit rates, when employed in conjunction with an adaptive modulation/channel coding scheme. Single relay cooperative system is commonly used, through which source can transmit the information directly to destination and also information transmitted through relay node [1] In this paper we propose basic knowledge about cooperative mesh network and its features. Fig: 1 Single relay cooperative system 11

2 In single relay cooperative system transmission of information between source node(s) and destination node (D) is not only by direct way but also through the relay node(r).the channel ĥij= hij / (PLij) 1/2 Where hij is an independent identically distributed complex Gaussian variable with zeo mean and unit variance. PLij = path loss factor = (4π) 2. (dij) 2 / Gt Gr λ 2 Power allocation scheme in single relay system can be given as mathimatically, Ώ=Received signal energy (S-R-D)/ Received signal energy(s-d) In [2] [3] it was shown significance of cooperative diversity and how it benefits in communication system, also researchers helps to describe cooperative ad hoc networks, cooperative mesh network. To the best of our knowledge, reference [6] is the first work discussed cooperative communication aware routing. In this work, the authors investigated the energy efficient routing which supports broadcast and cooperative communication. Cooperative diversity plays an important role to enhancing utility of cooperative communication system, papers [7-11] gives implementation and performance analysis of diversity and also researchers describe its outage behavior in wireless network with efficient protocols. MATLAB simulator tool is used for representing analytical results of the system. Brief explanation and knowledge about MATLAB software express in paper [18].The rest of this paper is organized as follows. Cooperative Diversity Protocols are given in section II. Problem definition of the system in section III. Methodology of the system is explained in section IV. Need of the tools for practical implementations are described in section V. II. COOPERATIVE DIVERSITY PROTOCOLS A. Cooperative diversity definition: Cooperative diversity is extension of spatial diversity which has aim to improve error performance. In spatial diversity, it may be possible for one user to receive the other signal, in this case it can forward some version of overheard information along with its own data. Cooperative diversity is a cooperative multiple antenna technique which improve total network for any given sets of bandwidths. Through these diversity techniques different sets of wireless terminals get benefits by relaying messages for each other to propagate redundant signals over multiple paths in the network. These diversity techniques can also be used to enhance bit rates, when employed in conjunction with an adaptive modulation/channel coding scheme. Equation shows a two-user multiple-access channel with cooperative diversity [7]. Although the model can be naturally extended to more than two cooperating terminals, we restrict our attention to the two-user cases for simplicity of exposition. Two sources generate independent messages w1 and w2. These messages are encoded into code words x1 and x2 that can also depend causally on the channel outputs (generalized feedback signals) y1 and y2, respectively. The decoder observes the channel output y0 and estimates the source messages as ŵ1 and ŵ2, respectively. In the complex Gaussian case, a discretetime, baseband equivalent channel model has, for each sample k Block diagram for a multiple-access channel with cooperative diversity This explains, why x1[k] (resp. x2[k]) a ects y1 [k] (resp. x2[k]) in above equation. y1 [k] = a1, 2 [k] x2[k] +z1 [k] And similarly for y2 [k]. And similarly for y2 [k]. Cooperative diversity transmission is performed by several numbers of protocols by which the information relayed to destination. Cooperative diversity protocols are described in detail by Leneman [13] and Aria Nosratinia and Ahmadreza Hedayat [14]. Cooperative diversity mainly uses fixed, selection and incremental relaying protocols Leneman [13] proposed all these protocols in 2004 and researches in this field are still going on to modify these protocols to obtain a better performance. Here we describe some of the basic relaying protocols, (i) fixed relaying protocol (ii) selection relaying protocol (iii) Incremental relaying protocol B. Cooperative protocols (I)Fixed Relaying The received signals will either be amplified, or re- encoded followed by decoding operation and retransmit the messages. It is classified into two parts. (i)amplify and Forward (AF): In AF, noisy versions of the transmitted signal from the partner users will be received at every user terminal. The user then amplifies and retransmits this noisy version. The base station proceeds the processing by combining the information sent by the user and partner users, and settles on a final decision about the transmitted bit. Even though the noise is amplified by cooperation, the base 12

3 station receives two independently faded forms of the signal and can make better decisions on the detection of data. The expression for probability of outage for amplify and forward scheme is given as [3] (ii) Decode and forward (DF): Aria Nosratinia and Ahmadreza Hedayat [14] describes decode and forward system as follows. In this decode and forward protocol user tries to decode the partner s data and then proceeds to retransmit the detected data. The base station then combines the data sent by the user and partner, and settles on a final decision about the transmitted bit. The decoding process at the relay terminal removes the noise unlike AF protocol. The expression for probability of outage for decode and forward scheme is given as (iii) Selection Relaying (SR) Selection relaying is performed by taking the fading coefficient into account. Optimum selection relaying protocols are discussed by Su and Xin Liu [15]. Fading coefficients [16] [17] can be measured accurately in cooperative terminals and they are known to the receivers. So in selection relaying, transmission is adapted in accordance with fading coefficients. Adaptation is done as stated below Measured fading coefficient falls below a certain threshold: The source progresses with its transmission to the destination, in the form of repetition or more powerful codes. Measured fading coefficient lies above the threshold: The relay progress with its transmission by either amplify and forward or decode and forward, in order to achieve diversity gain. (iv) Incremental Relaying (IR): According to this protocol relay retransmits only if the reception of the packet fails in first phase. IR can be of either IAF (Incremental Amplify and Forward) or IDF (Incremental Decode and Forward) based on the action that is performed by the relay. Amplify and Forward cooperative protocol transmission is the most simple and practical protocol. It is easy to implement but a major drawback is associated with it i.e. along with the signal amplification perpendicular noise amplification also takes place, which is unwanted. This problem is overcome by decode and forward relaying as this relaying scheme inherently eliminates the perpendicular noise. In coded cooperation, two mobile device affiliate with one another to collectively transmit the data. They use their resources collectively to achieve this. Since, the data is received via independent fading paths spatial diversity is achieved. III. PROBLEM DEFINITION The cooperative communication assumes that the base station can separately receive the original and relayed transmissions by transmitting the two parts orthogonally so that they can be separated. The most straightforward method is separation in time, the user s data and relayed data are transmitted in non-overlapping time intervals. In the example of Sendonaris et al [10, 11], orthogonality was achieved by spreading codes. In principle, it is also possible to achieve separation in frequency. Separation of signals is closely related to the issue of hardware requirements on the mobiles. In cellular systems, even time-division multiple access (TDMA) ones, the uplink and downlink transmissions are performed on separate frequency bands. Ordinary mobiles receive only in the downlink band, but cooperative mobiles need to also receive in the uplink band, thus requiring additional input filters and frequency conversion. In ad hoc wireless networks where users may transmit and receive on the same frequency band, this is less of an issue. Another technological issue is transmit and receive requirements on the mobiles. The performance of cooperative communications depends on careful resource allocation such as relay assignment and power allocation. The ever increasing demands of spectrum efficiency and link reliability are challenged by the impairments in wireless channel as well as resource constraints. These challenges can be overcome by the use of multiple antennas at the transmitter and receiver, commonly known as multipleinput multiple-output (MIMO) scheme. Fig: Cooperative Mesh Network The energy consumption must be minimized without compromising the quality of service (QOS). In this context, we present a novel energy allocation scheme for multiple relay nodes that results in efficient cooperative multiple-input multiple-output (MIMO) communication. The project objectives are mentioned below. Study and analysis of cooperative mesh networks Study of multiple-input multiple-output (MIMO) communication Study and analysis of power allocation for the MIMO cooperative network 13

4 Implementation of the approach using Mat lab software IV. METHODOLOGY The methodology we chose for this research is presented in this chapter. There are two types of methodology present which are qualitative and quantitative methodology. Research methodology is combination of qualitative and quantitative methodology which gives the idea about the power allocation scheme in cooperative system. The purpose of this qualitative study will be to understand and develop power allocation scheme for Cooperative communication system. A. Qualitative Research Methodology Qualitative approach is used when one is interested to explore any activity. For this research, we used qualitative research methodology in the following way; (i) Communication Background With the continuously growing demands for high data rate and reliable connection in wireless communication, the mobile telecommunication system also known as cellular network. The first generation (IG) cellular network is frequency division multiple access (FDMA) analog system. First system was takes place in NEW YORK, USA IN 1960 where a two way analog mobile phone system operated by high power base station (BS). At that time only user equipment s (UE s) were able to access the system simultaneously.in order to increase system capacity Bell Labs proposed a ground-breaking concept of cell (MacDonald 1979), it consist three novel ideas, frequency reuse, sectorization, and intercell handover. This idea help to system to allow more UE s to access the system simultaneously. In the following decade, some improvements was made on the 1G system. Improvements from 2G to 4G system is can be expressed by following figure. Though 4th generation network gives much advance facility to user but the most important work has to be done in this field. It has to develop in such way that systems should become more user friendly, energy efficient and economically efficient systems. Deep market penetration of powerful mobile communication devices such as laptops, smartphones, and tablets largely boosts the growth of wireless data traffic. In recent years, the worldwide wireless data traffic has been steadily increasing by more than 100% per year, so it is expected that after 10 years, the wireless communication system should be upgraded to generate 1000 times of data traffic provided by the current system to satisfy the basic requirement of communication service. Another challenge in front of next decade is rise of mobile internet communication. (iii) Development Requirements Considering challenges in next decade, some following requirements has to be taken into account to feature wireless communication: To achieve high wireless broadband capacity and focus on the optimization for the local area cell. Higher frequency spectrums should be put into use to obtain larger communication bandwidths. To enhance the system to support large amount of M2M communications. To strive for flexible, smart, and cost- efficiency network planning and deployment. Below flowchart DF relays pick up with SNR values greater than threshold,then proceeded for AF relay selection scheme, where inappropriate AF relays removed[19]. (ii) Challenges in the Next Decade The fourth generation wireless communication network included LTE-A (LONG TERM EVALUATION) and Wi Max systems, they are able to provide communication services for high transmission rate. Flow chart of dyanamic optimal combination strategy for the hybrid AF/DF cooperation uantitative Quantitative research is the systematic investigation of observable phenomena via statistical, mathematical or computational techniques. The objective of quantitative 14

5 research is to develop and employ mathematical models, theories and/or hypotheses pertaining to phenomena. B Figure: creation of user interfaces, and interfacing with programs written in other languages which include C, C++, Java, and Python. MATLAB tool box is based on communication and statistics. RAM is needed 2 GB. VI. CONCLUSION Fig: Block Diagram for Cooperative cooperative communication system with power allocation. The design steps based on research methodology can be explained in brief as below. The simulation parameters are defined as per MIMO wireless network. The project can be partition in two parts transmitter and receiver. The 2x2 MIMO transmitter with QPSK as modulation is used. A random signal is generated and made as QPSK signal and then used for power allocation. The power allocation is applied as per the allocation method. The signal is passed with noise in wireless channel. The signal is demodulated and received. The signal SNR and BER are calculated. In conventional AF, the transmission energy is equally distributed between the direct and the relayed link. This can lead to high energy consumption to achieve a particular performance. By varying the energy ratio between the direct and relayed link, a considerable amount of energy can be saved without affecting the quality of transmission. Thus the network life-time can be considerably increased. A. Software Requirement V. TOOLS USED The software used in this project for representing analytical results is a MATLAB Simulator Tool. MATLAB (matrix laboratory) is a computing environment and fourth generation programming language. It is widely used as a computational tool in science and engineering encompassing the fields of physics, chemistry, math and all engineering streams. It is used in a range of applications including: signal processing and Communications image and video Processing control systems test and measurement computational finance computational biology MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, Cooperative communication with single relay selection is a simple yet effective communication scheme for energy constrained networks. In this context we present basic idea about cooperative mesh network relaying protocols. Decode and forward relaying protocol is used to overcome from the drawback of amplify and forward relaying protocol. Here we show benefits of single relay cooperative network and also drawback of single relay network. We conclude the advantages of cooperative mesh network, which will provide direction to extend power allocation scheme for cooperative mesh network instead of single relay cooperative communication system. REFERENCES [1] Sarmad Sohaib, Daniel K. C. So and Junaid Ahmed Power Allocation For Efficient Cooperative Communiation, IEEE Transactions on Communication, 2009,pp [2] A.F.M Shahen Shah, Md. Shariful Islam A Survey on Cooperative Communication in Wireless Networks, I.J. Intelligent Systems and Applications, 2014, 07, Published Online June 2014 in MECS [3] Rinu Titus, Unnikrishnan M, Premkumar C.V A Survey On Incremental Relaying Protocols In Cooperative Communication, International Journal of Research in Engineering and Technology eissn: pissn: [4] Elza Erkip, Andrew Sendonaris, Andrej Stefanov,and Behnaam Aazhang Cooprative Communication In Wireless System DIMACS Series in Discrete Mathematics and Theoretical Computer Science,2009 [5] Jie Xu, Ling Qiu, and Chengwen Yu Improving Energy Efficiency Through Multimode Transmission in the Downlink MIMO Systems Eurasip Journal On Wireless Communications And Networking (2nd Revision) [6] Amir Khandani, Jinane Aboundi, Eytan Modiano, Lizhong Zheng, Cooperative Routing in Static Wireless Networks, IEEE Transactions on Communications, to appear, [7] J. Nicholas Laneman, Cooperative Diversity in Wireless Networks: Algorithms and Architectures Massachusetts Institute Of Technology, September 2002 [8] A. Sendonaris, E. Erkip, and B. Aazhang, User Cooperation Diversity Part I and Part II, IEEE 15

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