tailieunhanh - Advanced Transmission Techniques in WiMAX Part 9

Tham khảo tài liệu 'advanced transmission techniques in wimax part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 10 On PAPR Reduction Techniques in Mobile WiMAX Imran Baig and Varun Jeoti Universiti Teknologi PETRONAS Malaysia 1. Introduction The mobile Worldwide Interoperability for Microwave Access Mobile WiMAX air interface adopts orthogonal frequency division multiple access OFDMA as multiple access technique for its uplink UL and downlink DL to improve the multipath performance. All OFDMA based networks including mobile WiMAX experience the problem of high peak-to-average power ratio PAPR . The literature is replete with a large number of PAPR reduction techniques. Among them schemes like constellation shaping phase optimization nonlinear companding transforms tone reservation TR and tone injection TI clipping and filtering partial transmit sequence PTS precoding based techniques selective mapping SLM precoding based selective mapping PSLM and phase modulation transform are popular. The precoding based techniques however show great promise as they are simple linear techniques to implement without the need of any complex optimizations. This chapter reviews these PAPR reduction techniques and presents a Zadoff-Chu matrix transform ZCMT based precoding technique for PAPR reduction in mobile WiMAX systems. The mobile WiMAX systems employing random-interleaved OFDMA uplink system has been used for determining the improvement in PAPR performance of the technique. It has been further used in selective mapping SLM based ZCMT precoded random-interleaved OFDMA uplink system. PAPR of these systems are analyzed with the root-raised-cosine RRC pulse shaping to keep out-of-band radiation low and to meet the transmission spectrum mask requirement. Simulation results show that the proposed systems have low PAPR than the Walsh-Hadamard transform WHT precoded random-interleaved OFDMA uplink systems and the conventional random-interleaved OFDMA uplink systems. The symbol-error-rate SER performance of these uplink systems is also better than the conventional random-interleaved OFDMA uplink