Channel Estimation/Equalization with Adaptive Modulation and Coding over Multipath Faded Channels for WiMAX

Different order modulations combined with different
coding schemes, allow sending more bits per symbol, thus achieving
higher throughputs and better spectral efficiencies. However, it must
also be noted that when using a modulation technique such as 64-
QAM with less overhead bits, better signal-to-noise ratios (SNRs) are
needed to overcome any Inter symbol Interference (ISI) and maintain
a certain bit error ratio (BER). The use of adaptive modulation allows
wireless technologies to yielding higher throughputs while also
covering long distances. The aim of this paper is to implement an
Adaptive Modulation and Coding (AMC) features of the WiMAX
PHY in MATLAB and to analyze the performance of the system in
different channel conditions (AWGN, Rayleigh and Rician fading
channel) with channel estimation and blind equalization. Simulation
results have demonstrated that the increment in modulation order
causes to increment in throughput and BER values. These results
derived a trade-off among modulation order, FFT length, throughput,
BER value and spectral efficiency. The BER changes gradually for
AWGN channel and arbitrarily for Rayleigh and Rician fade
channels.

• B. Siva Kumar Reddy
• B. Lakshmi

• AMC
• CSI
• CMA
• OFDM
• OFDMA
• WiMAX.

[1] Andrews, Jeffrey G and Ghosh, Arunabha and Muhamed, Rias,
"Fundamentals of WiMAX: understanding broad band wireless
networking", Prentice Hall PTR, 2007.
[2] Kyro, Mikko, et al, "Measurement based path loss and delay spread
modeling in hospital environments at 60 GHz", IEEE Transactions on
Wireless Communications, Vol. 10, No. 8, pp. 2423-2427, 2011.
[3] Nee, Richard van and Prasad, Ramjee, "OFDM for wireless multimedia
communications", Artech House, 2000.
[4] B. Siva Kumar Reddy, B. Lakshmi, "Channel Estimation and
Equalization in OFDM Receiver for WiMAX with Rayleigh Distribution,” International Conference on Advanced Electronic systems
(ICAES), Rajasthan, 2013.
[5] Fantacci, Romano, et al. "Adaptive modulation and coding techniques
for OFDMA systems", IEEE Transactions on Wireless Communications,
Vol. 8, No.9, pp. 4876-4883 2009.
[6] Ibraheem Shayea, M. Ismail, Jamil Sultan, N. Misran, "Spectral
Efficiency of Mobile WiMAX Networks Employing Adaptive
Modulation and Coding", IEEE 10th Malaysia International conference
on Communications, 2011.
[7] Saleem, Saqib. "Performance and Complexity Comparison of Channel
Estimation Algorithms for OFDM System", International Journal of
Electrical & Computer Sciences, Vol. 11, No. 2, 2011.
[8] Panayirci, Erdal, Hakan Dogan, and H. Vincent Poor. "Low-complexity
MAP-based successive data detection for coded OFDM systems over
highly mobile wireless channels", IEEE Transactions on vehicular
Technology, Vol. 60, No.6, pp. 2849-2857, 2011.
[9] Ravindran, Niranjay, and Nihar Jindal. "Multi-user diversity vs. accurate
channel state information in MIMO downlink channels", IEEE
Transactions on Wireless Communications, Vol. 11, No.9, pp. 3037-
3046, 2012.
[10] Peng, Dezhong, et al. "CM-based blind equalization of time-varying
SIMO-FIR channel with single pulsation estimation", IEEE Transactions
on Vehicular Technology, Vol. 60, No.5, pp. 2410-2415, 2011.
[11] B. Siva Kumar Reddy, B. Lakshmi, "Adaptive Modulation and Coding
in COFDM for WiMAX Using LMS Channel Estimator,” Conference on
Advances in Communication and Control Systems (CACCS), Dehradun,
pp. 23-29, 2013.
[12] Yuan, Jenq-Tay, and Tzu-Chao Lin "Equalization and carrier phase
recovery of CMA and MMA in blind adaptive receivers", IEEE
Transactions on Signal Processing, Vol. 58, No.6, pp. 3206-3217, 2010.