Multi Carrier Frequency Hopping Spread Spectrum Techniques With Quasi-Cyclic Low Density Parity Check Codes Channel Coding

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dc.contributor.authorYahya, Abid
dc.date.accessioned2016-09-30T02:39:57Z
dc.date.available2016-09-30T02:39:57Z
dc.date.issued2010-04
dc.description.abstractThis work presents a new proposed Multicarrier Frequency Hopping Spread Spectrum (MCFH-SS) system employing Quasi-Cyclic Low Density Parity Check (QC-LDPC) codes instead of the conventional LDPC codes. A new technique for constructing thc QC-LDPC codcs bascd on row division method is proposed. The new codes offer more flexibility in terms of high girth, multiple code rates and block length. Moreover, a new scheme for channel prediction in MCFH-SS system is proposed. The technique adaptively estimates the channel conditions and eliminates the need for the system to transmit a request message prior to transmitting the packet data. The ready-to-use channel will be occupied with a Pseudonoise (PN) code and use for transmission or else, it will be banned. The new QC-LDPC codes are compared with other well established LDPC codes. The Bit Error Rate (BER) performance of the proposed QC-LDPC codes is evaluated and compared for short to longer block lengths with different code rates and fractional bandwidth, p. The new QC-LDPC codes show good BER performance as compared to the renowned Mackay and PEG codes for given values of Eb / No by 0.15 dB and 0.1 dB at a BER oflO-7 respectively. The proposed QC-LDPC codes are implemented on FPGA chip using Xilinx Spartan-3E development board. The results obtained for the hardware implementation of the proposed QC-LDPC codes with partial-parallel architecture accomplishes a throughput of 111.6 Mbps. Analysis of the hardware implemented QC-LDPC codes reveals that the new codes require less memory space, thus decreases the hardware complexity. The new QCLDPC codes are employed in the proposed MCFH-SS system as forward error correction (FEC) codes. The perfonnance of the proposed MCFH-SS system at diversity level 4, outperfonns MCFH-SS system (without channel prediction scheme) with 0.5 dB gain at p =1, when both systems are coupled with the proposed QC-LDPC codes. It is shown from simulation results that for 40 users at Eb / Jo of 5 dB, the proposed MCFH-SS system and fast frequency hopping spread spectrum (FFH-SS) system have BER of 10-6 and 10-4 respectively. The significant perfonnance enhancement has been observed for the same number of users (40) at high Eb / Jo of 50 dB that the proposed MCFH-SS system has BER of 10-7 while FFH-SS system with BER oflO-3 • Simulation results show that the proposed MCFHSS system achieves considerable advantage over the FFH-SS system when the systems are used under similar conditions. The overall proposed system is implemented on a hardware platfonn comprised of a communication development kit that is interfaced with Xilinx development board.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/2652
dc.subjectTransmit a request message prioren_US
dc.subjectTo transmitting the packet dataen_US
dc.titleMulti Carrier Frequency Hopping Spread Spectrum Techniques With Quasi-Cyclic Low Density Parity Check Codes Channel Codingen_US
dc.typeThesisen_US
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