Adaptive Communications for Noisy Signals in Low Rate Wireless Personal Area Networks
Thesis Type: Postgraduate
Institution Of The Thesis: Erciyes University, Mühendislik Fakültesi, Bilgisayar Mühendisliği, Turkey
Thesis Supervisor: Selçuk Ökdem
Approval Date: 2014
Thesis Language: Turkish
Abstract:
Wireless Personal Area Networks (WPANs) are computer networks used for data transmission among devices such as computers, telephones and industrial devices. These networks are operated in short ranges using low date rates and low-power radio signals. In wireless networks, it is importat to deliver data to the receiver with minimal error. It is referred as "data transfer rate" that gives amount of data transmitted/received without error in a time unit, which is an important measure in wireless communications. Data transfer rate is directly related to the amount of corrupted data in the transmitted data. The corruption on the data is dependent on the parameter of "bit error rate". Bit error rate of sent/received packets varies depending on data format. It is important to decrease negative effects of bit error rate in communications, and decide how to organize the format of the frame. Wireless Personal Area Networks for the IEEE 802.15.4 protocol is a used standard. IEEE 802.15.4 protocol defines two OSI layers called as Physical (PHY) layer and Media Access Control (MAC) layer. IEEE 802.15.4 PHY layer transfers data at 250 Kb/s using O-QPSK (Offset Quadrature Phase Shift Keying) modulation technique. Each packet is spitted into symbols including four data bits, and each of these symbols is translated to thirty-two bits Pseudo Noise(PN) chip sequences. In this thesis, it is aimed to find the best data chip sequences to obtain maximum data transfer in a time unit for different wireless channel types. To accomplish this, an adaptive data sequence generator mechanism is proposed. Performance analyses of IEEE 802.15.4 protocol with traditional and proposed PN sequences are made. The success of the proposal is illustrated in tables and graphs showing comparative performance results.