UWB (Ultra Wideband) Communication System 長庚電機通訊組 碩一 張晉銓 指導教授 : 黃文傑博士

Outline Overview UWB Spectrum Single-Band and Multiband Spectral Keying™ Modulation Conclusion

Overview UWB Spectrum 1/2 FCC ruling permits UWB spectrum overlay Bluetooth, b Cordless Phones Microwave Ovens GPS PCS a -41 dBm/Mhz “Part 15 Limit” UWB Spectrum Frequency (Ghz) Emitted Signal Power

High speed with low SNR (Shannon-Hartley law) Example: B = 7 GHz, SNR = 0.1, C = 0.96 GHz (UWB) B = 80 MHz, SNR = 10 3, C = 0.83 GHz (NB for music & VDO) Lower power consumption than NB (100x lower) Suitable for short-range wireless applications Overview UWB Spectrum 2/2

IEEE a

Single-Band and Multiband

Bandwidth and number of available band generate difference performance Singleband is more sensitive to ISI generated by delay spread Switching circuits problems Low duty cycle allows power saving features Minimizes collisions between colocated piconets??

UWB Multi-Band Technology UWB spectrum divided into multiple bands One symbol will be composed of subpulses from multiple bands Excellent performance in multipath Scalability − Bit rate − Power consumption − Range − Complexity / Cost Coexistence − IEEE a Regulatory − Compliant with US FCC − Flexibility for world-wide regulatory action

Multiband

Transmit 2 or more subpulses using different bands Order of bands defines symbol Transmit 2 or more subpulses using different bands Order of bands defines symbol Spectral Keying™ Modulation UWB Symbol in Time Voltage Time (ns)

Data encoded with –Sequence of bands in the pulse –Phase information on the subpulses SK Definitions

Spectral Keying General Case An SK symbol X, where can be defined in terms of the location in a M x T matrix, B and P where 0 means no transmission ±1 allows Binary Phase Shift Keying (BPSK) ± i allows Quadrature Phase Shift Keying (QPSK) M is # of frequency bands T is # of time slots B is # of non-zero entries P is # of polarity bits N is # of available bits For Optimum BER Performance in SK use M=T=B where

SK Rate Scalability Examples 2 bands no polarity 5 bands, with BPSK 8 bands with QPSK Sequence bits/sym. 1 ~6.5 ~15 Phase bits/sym Total bits/sym For sequence bits, the set of allowable symbols increases with the factorial of the number of bands

Multiband & Spectral Keying Multiband by QPSKSpectral Keying by BPSK

Conclusions A UWB system based on Spectral Keying TM will meet or exceed all selection criteria Spectral Keying TM is a Multi-Band scheme Good multipath performance Flexibility in assigning bands for regulatory and interference avoidance Unique high order modulation allows low symbol rate with long guard time between symbols Minimizes ISI - At maximum data rate no equalizer needed Off period is 75% at 13 MHz symbol rate - Allows power conservation Efficient spectrum utilization allows frequency based channels Provides scalability for power consumption, rate, range and complexity Technology proven with demonstrations Letter of assurance for essential patents submitted to the IEEE a leadership The May 2003 presentation will focus on analysis and simulation