Power line data transmission using an OFDM system

number: 
1777
English
Degree: 
Author: 
Shams Ayad Abd-Aljabbar Al-Aloosh
Supervisor: 
Dr. Nasser N. Khamiss
year: 
2008

Abstract : Ubiquitous high-speed communication is desirable, may be even essential for acceptable quality of life, productivity of business and so on. According to this demand, Power-Line Communication (PLC) arises in this field as a feasible broadband connection. The backbone of this system is of course the PLC modem which its design is a challenging task, as it covers several layers of the Open System Interconnection (OSI) standard. The Data Link layer comprises the security related investigations and the (MAC) layer problems while the Physical layer has to deal with all the modulation and hardware implementation problems, which is the concern of this thesis. The PLC modem here was designed to build the power-line network uses Orthogonal Frequency Division Multiplexing (OFDM), channel encoding techniques as well as a suitable Error Handling mechanism. This mechanism includes an error detection system followed by Forward Error Correction (FEC) which redundantly encodes the data to compensate for harsh channel characteristics using Reed Solomon codes. The encoded data was mapped onto a set of tones each with a different capacity and according to the spectral mask. OFDM modulation was generated using a Fast Fourier Transform (FFT) process. After mirroring the data, to get real time domain samples, the Inverse FFT was applied at the transmitter to produce an OFDM symbol. The orthogonal symbols then submitted to the addition of the Cyclic Prefix (CP) to mitigate Inter-Symbol-Interference (ISI) and Inter-Carrier- Interference (ICI), then these operations were reversed at the receiver. In the part of the Mirroring process as well as in the Cyclic Prefix, a proposed idea was applied that divides the data stream into three parallel substreams where each one can be processed independently at the same time. This idea will be useful as it consumes time to be 1/3 of the processing time needed in the real time design in spite of raising the cost as a disadvantage. The PLC modem design was implemented using matlab V 7.0 and the obtained results showed the importance of the FEC and the channel effects related to the SNR where it is tested on both AWGN channel and the simulated PLC channel. Then a colored image was transmitted using the proposed design and the obtained data rate was about 100 Mbps which is sufficient to fulfill the broadband services.