Page 1 Effective Synchronization Scheme for Impulse Radio Ultra Wideband Systems 適用於脈衝無線電超寬頻系統之有效率的同步 機制 東海大學．電機工程學系 溫志宏 教授
Page 2 Outline What’s Ultra Wideband? Symbol-Differential UWB System Frame-Differential UWB System Proposed Synchronization Scheme Performance Analysis Simulation Results Conclusion
Page 3 What is ultra-wideband? Ultra wideband (UWB) Bandwidth is wider than 500 MHz Fractional bandwidth is greater than 0.2 Time hopping impulse radio (TH-IR) UWB Based on transmitting very short and low power pulses Pulses are transmitted in the frames based on the specific pseudo random (PN) time hopping code ( ) assigned for each users
Page 4 Symbol-Differential UWB System
Page 5 Symbol-Differential UWB System The transmitted signal of the symbol differential scheme, with a is any M-ary PAM symbol. : the transmitted pulse energy. : the normalized pulse. : the number of frames in one symbol. : the frame duration : the time hopping code. : the chip duration
Page 6 Architecture of Symbol-Differential Receiver K: pair of symbol
Page 7 Synchronization algorithm (Timing with Dirty Template; TDT) K K-K K K-K K -K K-K -K K-K -K +1
Page 8 Symbol-differential 需花費的時間： Ex:
Page 9 Frame-Differential UWB System
Page 10 Signal Model Data symbol, where is the data symbol index. Each information bit is modulated by BPSK. A known random polarity sequence is differentially modulated on the monocycle pulses, where is the pulse index within a symbol. Each pulse is differentially modulated by both BPSK and random polarity sequence, the differentially modulated pulse- polarities are obtained as and.
Page 11 The time shifts between pulses are defined as and. Here, we let for. symbol Ex:
Page 12 The transmitted signal of this UWB system can be expressed as: : the symbol index : the frame index : the pulse-polarity : the frame duration : the chip duration : the transmitted pulse waveform
Page 13 Frame-Differential Receiver Delay Decision and Control Logic Delay Integrated & Dumped
Page 14 Frame-differential 需花費的時間： Ex:
Page 15 Proposed Synchronization Scheme Parallel signal acquisition with shared loop delay line (PS-SLD)
Page 16 Proposed Receiver Architecture Delay Decision and Control Logic
Page 17 : 開始積分時間 : 接收起始點 : 開始有值輸出 接地的時間接收資料的時間
Page 18 : 開始積分時間 : 接收起始點 : 開始有值輸出 接地的時間接收資料的時間
Page 19 : 開始積分時間 : 接收起始點 : 開始有值輸出 接地的時間接收資料的時間
Page 20 : 開始積分時間 : 接收起始點 : 開始有值輸出 接地的時間接收資料的時間
Page 21 接地的時間接收資料的時間接地的時間接收資料的時間接地的時間接收資料的時間接地的時間接收資料的時間 : 開始積分時間 : 接收起始點 : 開始有值輸出 積分器開始積的時間 : 開始接地的時間 : 開始接收資料的時間 :
Page 22 Proposed synchronization scheme 需花費的時間： Ex:
Page 23 Performance Analysis
Page 24 Signal Model Transmitted signal of the k-th user i : the symbol index j : the frame index : symbol duration
Page 25 The multipath channel corresponding to every user k is modeled as a tap delay line with taps : amplitudes of multipath signals : delays of multipath signals, and is defined : the propagation delay of the first arrival signal
Page 26 Received signal where
Page 27 Autocorrelation output
Page 28 the desired signal terms can be extracted with indexes,,,,
Page 29 Let, and Since, and
Page 30 Assuming If is neglected, then exhibits a maximum when The estimated propagation delay is given by
Page 31 Probability of detection (PD) The probability of detection is denoted as Assuming and are target indexes, and represents the inaccuracy between the declared symbol boundary and the true symbol boundary The pdf of based on each determined is given as The probability of detection (PD) for every and based on a determined is given as
Page 32 Let,where and satisfy Assuming that is uniformly distributed over interval of
Page 33 Lower bound of PD Through the central limit theorem, can be treated as Gaussian distributed where
Page 34 Simulation results
Page 35 Parameters Under UWB CM1 with (1/ , 1/, , )=(42.9, 0.4, 7.1, 4.3)
Page 36 Theoretical results For the simulation result,
Page 37 Probability of Detection (PD) Shift step size:
Page 38 Normalized Mean Square Error (MSE) Shift step size:
Page 39 Normalized MSE Shift step size:
Page 40 Conclusion PS-SLD has a higher hardware complexity than the TDT scheme The performance of PS-SLD in both PD and MSE is better than that of TDT, especially in multi-user environments The synchronization speed of PS-SLD is also faster than that of TDT algorithm Uncertain region is bounded within one frame duration, and is only of that of the TDT
Page 41 Appendix Proof of Eq. 3