Informatics Publishing Limited

V. Savarna ¹, B. Kaarthick ¹

Affiliations
1 Coimbatore Institute of Engineering and Technology, IN

Abstract

Wireless Networks have become the most effective and affordable option for connectivity, promoting the spirit of sharing bandwidth. The consequences encountered due to interference problem are getting prevalent because of their operation in the unlicensed frequency band and Orthogonal Frequency Division Multiplexing (OFDM) comes as an option to resolve this issue. OFDM is a multicarrier modulation technique employed mostly in IEEE 802.11a/g/n, IEEE 802.16 and LTE standards. One of its major shortcomings is its high PAPR value. Clipping and filtering is one of the simplest and promising approach to obtain a PAPR reduction. Various optimal algorithms achieve the required PAPR performance and recently Zhu, Hong, Tang and Wensheng investigated the clipped noise and proposed a modified algorithm called SOICF which can achieve minimum in band distortion. In this proposed algorithm a compression technique follows the technique used in SOICF, which assures less PAPR. It also ensures zero out of band radiation.

Keywords

PAPR, EVM, OFDM, Clipping and Filtering.

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B. Kaarthick ¹, V. J. Yeshwenth ², P. M. Sudarsan ², N. Nagarajan ³, Rajeev ⁴

Affiliations
1 Network System Design Center, Sri Krishna College of Engineering and Technology, Coimbatore, IN
2 University of Texas at Dallas, US
3 Coimbatore Institute of Eng. and Information Technology, Coimbatore, IN
4 Wipro Technologies, IN

Abstract

IEEE 802.16e, a broadband wireless access technology that provides high speed internet access and multimedia services has seen very significant growth in recent times. With the due rapid deployment of WiMAX, there would be a growing demand for efficient support of voice applications. The performance of Voice over IP services depends on a proper scheduling algorithm combined with a proper Voice encoder scheme. The contribution of this work is two fold. The first is that we present an efficient scheduling algorithm that can be used for VoIP services in IEEE 802.16e. We then implement the algorithm in various CODECS and compare the performance of the codec's i.e.G.728, G.711, G.723, G.729, G.726, GSM-EFR, GSM-HR under similar load conditions for Interactive voice over WiMAX by enabling the Speech Activity Detection (SAD). We analyze the system throughput and delay to evaluate the performance of our algorithm and the primary metrics that were used in the comparison for choosing the right vocoders for the algorithm were Jitter, MOS, and packet end to end delay.

Keywords

QoS, vocoders, Jitter, VoIP, MOS.

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