doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: TG4a UWB-H-IR Modulation schemes and preliminary simulation results Date Submitted: 21 April 2005 Source: Philip Orlik, Andy Molisch (Mitsubishi Electric), Contact: Philip Orlik Voice: , Abstract: Yet another UWB waveform Purpose:To provide information for further investigation on and selection of the modulation /waveform for UWB Impulse Radio (low bit rate plus ranging) Notice:This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release:The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 2 IEEE a PHY: UWB-IR Modulation for multiple receiver types

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 3 Hybrid - Impulse Radio Modulation Scheme Rake Receiver Finger Np Rake Receiver Finger 2 Rake Receiver Finger 1 Summer TdTd Coherent Receiver Differentially Coherent Receiver Hybrid Transmitter ( ) 2 Non-Coherent Receiver Pulse Gen. TH Seq BPSK symbol mapper Delay Central Timing Control Multipl exer

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 4 Differential Encoding: Basics TsTs b0b0 b4b4 b3b3 b2b2 b1b1 b5b5 b -1 Tx Bits Reference Polarity

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 5 Pros/Cons of RX Architectures Coherent + : Sensitivity + : Use of polarity to carry data + : Optimal processing gain achievable - : Complexity of channel estimation and RAKE receiver - : Longer acquisition time Differentially-Coherent (or using Transmitted Reference) + : Gives a reference for faster channel estimation (coherent approach) + : No channel estimation (non-coherent approach) - : Asymptotic loss of 3dB for transmitted reference Non-coherent + : Low complexity + : Acquisition speed - : Sensitivity, robustness to SOP and interferers

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 6 Waveform Design (1/2) H-IR: Combination of BPPM with BPSK and TR Guarantee coexistence of coherent, non-coherent and differentially coherent receiver architectures: –Non-coherent receivers just look for energy in the early or late slots to decode the bit (BPPM) –Coherent and differentially-coherent receivers, in addition, understand the fine structure of the signal (BPSK or DBPSK) Principle: Non-coherent and differentially- coherent modes should not penalize coherent RX performance

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 7 Waveform Design (2/2) Two possible combinations of BPPM and H-IR: 1) The whole symbol (consisting of N f frames) is BPPM-modulated 2) Apply 2-ary time hopping code, so that each frame has BPPM according to TH code (Simulations carried out for this case) Coexistence coherent/non-coherent RX: - Special encoding and waveform shaping within each frame - Use of doublets with memory from previous bit (encoding of reference pulse with previous bit) - Proposed 10ns separation between pulses - Extensible to higher order TR for either reducing the penalty in transmitting the reference pulse or increasing the bit rate (see: a for detail) - Also possible the use of multi-doublets (see a)

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 8 Example Signal Waveforms for data modulation (1) b i-1 = 1, b i = 1 b i-1 = 0, b i = 1 b i-1 = 0, b i = 0 b i-1 = 1, b i = 0

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 9 Example Signal Waveforms for data modulation (2) Ts « 11 » « 01 » 2-PPM + TR base M = 2 One bit/symbol « 10 » « 00 » (coherent decoding possible) Divide each frame into two halves for inclusion of BPPM modulation. In either half transmit a doublet according to previous H-IR coding.

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 10 Design Parameters Pulse Repetition Period (PRP)  Proposed range between 18 – 28ns Channelization (In addition to FDM)  Coherent schemes: Use of TH codes and polarity codes  Non-coherent schemes: Use of TH codes (polarity codes for spectrum smoothing only) TH code length  TH code length: 8  TH code: Binary position, bi-phase

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 11 Coherent AWGN Performance 1.5 dB Coherent CM8 Performance 1 dB Hybrid modulation can be viewed as a form of TCM, we get some coding gain, albeit small.

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 12 Coherent Performance with Additional rate ½ FEC

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 13 Simulation Parameters UWB signal characteristics: Channel separation = 494 MHz Center frequency = GHz Pulse shape: root raised cosine (roll-off 0.25, 4ns width) Average Doublet Repetition Rate = 52.6 MHz Delay Between Reference and Data Pulse = 10ns Chip time (T c ) = 4 ns Frame levels (N f ) = 8 Guard time/frame (T g ) = 10 ns TH sequence length (L PN ) = 8 Symbol time N f * (2 * (T g + 2*T c + T d )) = 448 ns Packet length = 32*8 bits = 256 bits (uncoded) Channel coding: rate ½, K=5. Rate (R) = 1.11 Mbit/s

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 14 Waveforms Parameters Binary modulation approximately, 1Mbps with Rate ½ coding (500ns for symbol) Pulse shape: root raised cosine (roll-off 0.25, 4ns width) T d = 10ns (Doublet delay ) T c = (2* ) = 28ns (Chip Duration) T f = 2*T c = 56ns (Frame Duration ) TH code length 8. Tc TfTf

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 15 AWGN Comparisons

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 16 Packet Error rates in CM1 environment: Differential (TR), Coherent

doc.: IEEE a TG4a July 18th 2005 P.Orlik, A. Molisch, Z. SahinogluSlide 17 Advantages Coherent RX gets additional benefit from coding inherent in the modulation Waveform permits polarity scrambling to reduce required back-off A single waveform for all receiver types