Wireless Communication

V. Venkataramanan ¹, M. Kavitha ¹

Affiliations
1 Electronics and Communication, Anna University, Arunai College of Engineering, Thiruvannamalai, IN

Abstract

Despite their tremendous success over the years, the wireless technologies are still confronted with some of the critical challenges such as, fading, multipath, and interference and spectrum limitations. To fulfill this, wireless communication industry worked hard and defined a new air interface for mobile communications. That is Long Term Evolution (LTE ), is the evolution of the Universal Mobile Telecommunication System describes standardization work by the 3rd Generation Partnership Project. It enhances the overall system performance by increasing the capacity of the system along with improving spectral efficiencies while reducing latencies. In order to achieve above requirements important changes have been required at the physical layer e.g. new modulation and coding schemes, reduced Transmission Time Interval (TTI) or advanced medium access techniques. In this paper, the main objective is to investigate a downlink and uplink physical layer performance of Long Term Evolution system.

Keywords

LTE, OFDM, SC-FDMA, 3GPP.

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P. Mayil Vel Kumar ¹, S. Annapoorani Mala ², M. Kavitha ³

Affiliations
1 Department of CSE, Karpagam Institute of Technology, Coimbatore, IN
2 Department of Information Technology, Karpagam Institute of Technology, Coimbatore, IN
3 Department of Computer Science and Engineering, Anna University Technology, Coimbatore, IN

Abstract

World Interoperability for Microwave Access (WiMax) is one of the leading technologies in the context of Broadband Wireless Access (BWA). The Bandwidth reservation allows IEEE 802.16 networks to provide QoS guaranteed services. The SS (Subscriber Stations) reserves the required bandwidth before any data transmissions. Due to the nature of VBR applications, it is very difficult for the SS to make the optimal bandwidth reservation. It is possible that the amount of reserved bandwidth is more than the demand. Therefore, the reserved bandwidth cannot be fully utilized. Although the reserved bandwidth can be adjusted via BRs, however, the updated reserved bandwidth is applied as early as to the next coming frame. The new scheme is ‘Bandwidth recycling’. In this scheme, the SS releases its unused bandwidth in the current frame and another SS pre-assigned by the BS has opportunities to utilize this unused bandwidth. This improves the bandwidth utilization. Moreover, since the existing bandwidth reservation is not changed, the same QoS guaranteed services are provided without introducing any extra delay. The three additional algorithms have been proposed to improve the recycling effectiveness.

Keywords

QoS, VBR, BS, SS, BR, WiMax.

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