Multiplexing Techniques Performance analysis and linking to OFDM and MIMO

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1 ISSN No: Journal of Computer Science and Engineering Research: 2014, 1 (1):1-5 Multiplexing Techniques Performance analysis and linking to OFDM and MIMO 1 P. Karthik and 2 G. Kumaran 1 Embedded System Technologies, SKP Engineering College, Tiruvannamalai, India 2 ECE, SKP Engineering College, Tiruvannamalai, India ABSTRACT The objective of this paper is to analyze the performances in various multiplexing techniques and compare to orthogonal frequency multiple access (OFDMA) and multiple input and multiple output (MIMO) schemes. Long term evolution (LTE) and LTE- Advanced (LTE-A) is mainly focus on high data rate, mobility, low latency, quality of service (QOS), mobile TV and virtual environment services. The OFDMA-MIMO systems to avoiding intercell interference (ICI), signal to noise ratio (SNR) and high performance achieved without any optimization techniques. The performance analysis of OFDMA-MIMO is done in simulation using MATLAB. Keywords:-OFDMA, MIMO, LTE, ICI, SNR INTRODUCTION The Next generation wireless cellular networks increasing the users and introduce the new features such as smart technologies. The fourth generation network (4G) called ass LTE and LTE-A [1], Bandwidth utilization is maximum and providing high mobility of service without any interference of data. OFDMA [2] is the opportunistic spectrum usage and the subcarrier allocation is easy and providing high security of the systems and frequency reuse, large coverage area, dynamic channel sharing, information transfer over the large bandwidth. The multiple access techniques [3] such as FDMA, TDMA, CDMA is providing the voice communication and not suitable for high data rate transmission of the systems, this problems are overcome to next generation cellular networks. MIMO [16], [19] is the large packets transmit same time and more channel are used.multiuser-ofdma and multiuser MIMO is used for 3GPP and LTE, its applicable for downlink transmission systems. The Uplink transmission [12], [18] single carrier FDMA is used. WiMax [17] technology is providing high data rate and the standard is IEEE frequency range is 10-66GHz. The interference cancellation and frequency reuse [11], [12], [14], its same frequency is used again another one cell and spectrum usage is reduced and minimizing the interference using recent multiplexing techniques such as OFDMA, MIMO, LTE-A. In this paper section-ii introduction of all multiple access technique and section III comparative analysis, finally section-iv conclusion is provides the next generation of scope. MULTIPLEXING TECHNIQUES FDMA This technique is used for advanced mobile phone system (AMPS), uses separate frequency for each user. The frequency range for uplink is MHz and Downlink frequency range is MHz, each frequency is 30 khz wide. Channel usage is maximum, its operates at data link layer and static system. The carrier frequency is temporary basis implement to users, the FDMA systems interference is occur transmission of data. The calculation of number of channels in FDMA systems is = Where, N Number of channels, B c Channel Bandwidth, B t Total spectrum allocation, B guard Guard band. TDMA Time division multiple access (TDMA) is an access to users separated in time. It s a digital system, continuous transmission is not required because users do not use the allocated bandwidth at all time. Entire bandwidth is available to the users but only used for finite period of time. The guard time is spacing between the TDM, the frequency separated for time slots. The TDMA systems number of channels as follows 1

2 = ( 2 ) Where, N Number of channels, M Number of TDMA users ratio channel, B tot Total spectrum allocation, B c channel bandwidth, B guard Guard Band. CDMA In code division multiple access is all users occupy the same bandwidth, however they are assigned separate codes. The Receiver known the code to separate the original information to be received, in between cross connection of other user is lesser possible and encoding and decoding process is followed. The CDMA scheme is the transmission information receiver side arrival is different time periods, the encoding scheme is adding ideal orthogonal codes, Gold code (or) Kasami code, Pseudo random (or) pseudo noise (PN) to the original data. The modulation scheme is original data added to the code and perform X-OR operation, all users occupy same channel by only users to associated with a particular code to communicate with each other. Bandwidth of the CDMA is propositional to the 1/T, where T Bit time. OFDMA The OFDMA systems available frequency is dividing to many subcarriers and separated to non-overlapping subnets. The block diagram (fig: 5) shows the information modulation and transmission to the channel and reverse operation perform receiver side. The scheme is transmission of information at multipath propagation so avoiding loss to adding cyclic prefix, the modulation scheme is used for DFT and IDFT using FFT and IFFT. All modulated subcarriers are transmitted in parallel. It s the bandwidth options are 1.25, 5, 10 and 20MHz. Entire bandwidth separated by 128, 512, 1024 sub carrier, OFDMA is the large amplitude variation and the interference is minimum. The synchronization required for TDMA and FDMA, next generation systems not needed for the synchronization technique. Fig: 1 General OFDMA subcarrier allocation The subcarrier or frequency carrier 1024 in 720 carriers only used for transfer the information and remaining is reserved for pilots and guard interval, cyclic prefix. It s allocated for the downlink frequency selection. The OFDM systems subcarrier are large amplitude variation with other carrier channel, the integration signal and adding value in zero. The retransmission of information specific data only transmitted to the user. Fig: 2 OFDMA symbol packing subcarrier allocation Out of 720 subcarriers are divided to 30 sub channels (each sub channel contain 24-sub carriers).the OFDMA systems dynamic sub channel allocation in Mobile station, for example consider MS1 and MS2,..first (0-5) sub channel allocated to MS1 and (6-25) sub carrier allocated to MS2,(1-6) sub carriers are allocated another MS etc respectively allocated the number of users 2

3 Fig: 3 OFDMA sub channel allocation SC FDMA Single carrier OFDMA is multiple users to share the communication resources, it s used for the uplink data transmission such as mobile station to base station. In order to peak to average power ratio (PAPR) is reduced for using SC-FDMA. Fig: 4 SC FDMA sub channel allocation Fig: 5 OFDMA Block diagram The multicarrier signal are merged to the subcarrier signals at the uplink transmission. The system is increased by 2 3 db power to compensate the noise. MIMO Multiple input multiple output systems used for transmitted information and received information in multiple antennas for improve the communication performance, its additional bandwidth and improve the power in transmitter coverage area and achieve high diversity gain, reduced the normal ratio transmission causes the interference but MIMO systems provide maximum gain archived at the receiver coverage area. 3

4 Diversity (Transmitter &Receiver) The transmit diversity is the technique to the receiver coverage area effect of the fading reduced over a communication link, multiple antennas at the transmitter and receiver side. Fig: 6 Transmit Vs Receiver diversity The fig:6 shows the [1*1 notational] antenna archived is maximum bit error rate and transmission side number of antennas increasing [2*1 notational] and transmit diversity is increased. The BER is increased through the increase transmitter in base station. Fig: 7 orthogonal diversity The desired performance achieved in receiver coverage area and reduce the BER using multiple antenna at the receiver side. Table 1: Performance analysis of various multiplexing techniques Parameter FDMA TDMA CDMA OFDMA MIMO Single Channel used scenario Frequency Time slot Signature sequence Orthogonal frequency Orthogonal frequency Modulation Scheme FSK QPSK,GFSK Spread spectrum QAM Spatial modulation ISI elimination Guard Equalization Rake receiver Cyclic prefix Cyclic prefix interval Intra cell interference Not necessary Not necessary MUD Not necessary Not necessary cancellation Inter cell interference Sensitive Sensitive Mitigated Sensitive Mitigated Synchronization required Yes Yes No Yes Yes Bandwidth (Hz) 30k 200k 5M 20M 20M Data rate 28-56kbps kbps 200kbps-sevaral Mbps Up to 1Gbps Up to 1Gbps 4

5 COMPARATIVE ANALYSIS All Multiplexing techniques main features are compare to OFDMA and MIMO systems is suitable for next generation wireless networks, the inter cell interference is minimum and no inter symbol interference. The frame transmission and reception is efficient for LTE systems, BER is minimum. The Wi-max is high performance like multimedia services of without any interference. CONCLUSION This paper performance analysis of various multiplexing technique and compare to OFDMA and MIMO, the schemes all features are supported like all multimedia applications. All base station coordinate with each other, so interference is not occur. The future wireless cellular network like LTE and LTE-A systems high performance achieved anywhere. REFERENCES [1] Jayanthiladevi, A. ; Premlatha, H.M. ; Nawaz, G.M.K. Analysis study of seamless integration and intelligent solution in any situation by the future advanced mobile universal systems 4G - (FAMOUS4G), 2013 International Conference on Emerging Trends in VLSI, Embedded System, Nano Electronics and Telecommunication System (ICEVENT), Publication Year: 2013, Page(s): 1 5 [2] Jihoon Park; Pawelczak, P.; Gronsund, P. ; Cabric, D. Analysis Framework for Opportunistic Spectrum OFDMA and Its Application to the IEEE Standard IEEE Transactions on Vehicular Technology, Volume: 61, Issue: 5 [3] Pingzhi Fan, Multiple Access Technologies for Next Generation Mobile Communications, 6thInternational Conference on ITS Telecommunications Proceedings, 2006 [4] S. Haykin, Digital Communication, John Wiley & Sons, Inc., Replika Press Pvt. Ltd., N. Delhi, India, [5] A.B. Carlson, P.B. Crilly, J.C. Rutledge, Communication Systems, McGraw-Hill, Singapore, International Edition, 2002, (4 th Ed.). [6] K.S. Shanmugam, Digital & Analog Communication, John Wiley &Sons, Inc., Replika Press Pvt. Ltd., N. Delhi, India, [7] B.P. LATHI, Modern Digital and Analog Communication Systems, Oxford University Press, New Delhi, India, (3rd Ed.). [8] N. Sarkar, elements of Digital Communication Systems, Oxford University Press, New Delhi, India, 203 (Ist Ed.).Eli Sofer, Yossi Segal Tutorial on multi access OFDM (OFDMA) technology, IEEE Jan, 2005 [9] A.C. Mc Cormick and E.A. Al-Susa, Multicarrier for future generation Mobile Communication, IEEE, April [10] X. Huang,Yu, E. Dutkiewicz, and M. Mueck, Load distribution aware soft frequency reuse for inter-cell interference mitigation and throughput maximization in LTE networks, in Proc IEEE International Conference on Communications, pp [11] M. Necker, Interference coordination in cellular OFDMA networks, IEEE Network, vol. 22, no. 6, pp , [12] X. Mao, A. Maaref, and K. Teo, Adaptive soft frequency reuse for intercell interference coordination in SC-FDMA based 3GPP LTE uplinks, in Proc IEEE Global Telecommunications Conference, pp.1 6. [13] Ramjee Prasad and Tero O Janepera, A Survey on CDMA: A Evolution towards Wideband CDMA in proc. of IEEE, 1998 [14] Suzuki, T. ; Tanaka, T. Study on canceling inter symbol interference of inverse-gps, th International Conference on Signal Processing,Volume: 2 Publication Year: 2002, Page(s): vol.2 [15] D. Astely, E. Dahlman, A. Furuskar, Y. Jading, M. Lindstrom, and S. Parkvall, LTE: the evolution of mobile broadband [LTE part II: 3GPP release 8], IEEE Commun. Mag., vol. 47, no. 4, pp , 2009 [16] Torlak, M.; Duman, T.M. MIMO communication theory, algorithms, and prototyping, 20th Signal Processing and Communications Applications Conference (SIU), 2012 Pub Year: 2012, Page(s): 1-2 [17] K. Etemad, Overview of mobile WiMAX technology and evolution, IEEE Commun. Mag., vol. 46, no. 10, pp , 2008 [18] Ng, B.K.; Chan Tong Lam On maximizing the performance of SC-FDMAsystems with rotated constellation th International on Wireless Communications and Mobile Computing Conference (IWCMC), Publication Year: 2013, Page(s): [19] Ebrahim karami Performance analysis of decision directed likelihood mimo channel tracking algorithm, vol 26,pp [20] Kusume, K.; Dietl, G.; Abe, T. ; Taoka, H.; Nagata, S. System Level Performance of Downlink MU-MIMOTransmission for 3GPP LTE- Advanced 2010 IEEE 71st Vehicular Technology Conference (VTC2010-Spring), Publication Year: 2010, Page(s): 1 5 5