Publisher's Synopsis
Two important topics of information theory are compression and error correction codes. These
are known as source and channel coding techniques. Source coding helps to compress the data
and improves bandwidth utilization. Channel coding adds redundancy to make data more reliable.
Error correction coding is the means whereby errors can be detected and corrected using
redundant bits. Error correction codes are of two types, forward error correction and automatic
repeat request.
Mobile communications have seminal importance in present telecommunication systems.
Wireless transmission is used to convey data between user end and base stations. The
communication errors are caused due to noise, interference and poor signal strength. Mobile
communication system presently uses Turbo channel code to detect and correct errors.
Presently, there is a high demand for mobile services and its applications. Usage of smart
phones has increased largely and that is demanding higher data rate and large network capacity to
meet intensive service requirements. This demands large bandwidth which is limited and valuable
resource. The requirements to support real time voice communication in mobile system with
different available standards are Bit Error Rate and Latency. Further, the capacity to scale up in
channels, coverage area and seamless integration of Polar-code based systems with minimum
design efforts are thrust areas.
Shannon, pioneer of information theory expressed in year 1948, that data can be
transmitted reliably through the channel at maximal possible rate. The prime goal of coding
theory since 1948 till date is to design a practical error correcting coding scheme that can be
implemented in real time communication. The work focuses on developing such practical Polarcode
based system. Polar-codes was introduced by Erdal Arikan in 2009. The application
considered in present work is voice and data for mobile communication. Polar-code is used along
with spectrum efficient MPSK modulation techniques in the presence of additive white Gaussian
noise. The main objective is to increase the number of users with same bandwidth. Simulation is
carried out to optimize the Power, Bandwidth and Latency parameters for acceptable Bit Error
Rate of 10-4. Taguchi and Response Surface Methodology techniques are used for performance
optimization using Polar-code.
A single transmission time interval mechanism is used for circuit switching technique.
Based on this, a Polar-code based OFDM system is simulated with 12 subcarriers. It is observed
that the SNR required to achieve BER of 10-4 is 5.84 dB, 12.62 dB, 18.84 dB for QPSK, 8 PSK
and 16 PSK modulations respectively. To extend the applicability to packet switching technique
with BER of 10-4, three transmission time intervals mechanism is simulated with Polar-code
OFDM system. The SNR of 2.84 dB, 9.62 dB, 15.84 dB is obtained for QPSK, 8 PSK and 16
PSK modulations respectively.
The experimentation has been carried on a frame of length 528 bits with QPSK and 16
PSK OFDM system. Here Polar-code is used for bit error correction and CRC of 8-bit, for frame
error detection. The frame error rate considered is of 10-3 and 10-4. This system provides link
utilization of 32.43% and 32.46 % for data rate of 100 Mbps. With 10 Mbps data rate, link
utilization achieved is 75% and 83.32 %.
