ontent Basics o UWB Technologies - Utilization o Wide Spectrum - What is UWB History and Recent Trend o UWB Principle o UWB Application o UWB Technical Issues or Antennas & RF ircuits Intererence Problem onclusion 1 UWB Ultra Wide Band (more than 25% relative bandwidth transmission) By Using Short Impulse or Monocycle Signals, ommunication/sensing/ Imaging technologies In 2002 F allowed an use o UWB spectrum Physical Layer Technologies adopted or IEEE 801.15 arrier-less: IF ircuits, Mixer, etc are not required Originally, Military Radar/ommunication Technology History and Recent Trend o UWB 1901 Marconi s rontier work on wireless communication is an Impulse transmission. 1998 Time Domain Inc. etc, asked F to use UWB. 1998 F started a technical review on UWB. 2002, 2 F allowed a commercial use or UWB. 2002, 5 First International onerence on UWB 2002, 9 UWB SG organized by MPT, Japan 2 3 1
UWB Technology Basics: Wide Band & Low Power Density Spectrum Mask by F 4 5 Equivalent Noise Temperature Multi-Band OFDM proposed by Intel -41.3dBm/MHz 0.742 10^-13 [Joule] kt:power Spectrum Density T=5.38 10^9 [ ] Too High Temperature!! 6 7 2
UWB s Application Imaging Systems Ground Penetrating Radar Wall-Imaging, Through-Wall Imaging Medical-Imaging Vehicular Radar Systems ollision Avoidance Radar ommunication Systems Short Range (~10m) ommunications WPAN (Wireless Personal Network) Xtreme Spectrum s View o Home Networking Nodes orm a mesh to extend range throughout house http://www.xtremespectrum.com/products/uwbwhitepaper.pd 8 9 Prototypes by Venture ompanies Time Domain (From 1989) Pulse On 200 Xtreme Spectrum Inc. Data Rate 100Mbps (High Speed) Transmission Power 200mW (Low Power) Broad Band Transmission hannel apacity S Where Upper Bound : signal power : noise power : bandwidth W 0 10 N W N 0 W log2 1 S N W log 21 S WN0 : noise power spectrum density S ln 2 N S lim ln 2 N 0 11 3
Low Power Transmission by Wide Band Principle o UWB Transmission hannel apacity is a monotonic increasing unction o bandwidth W or given S and N_0 But there is an upper bound For thermal noise N_0 ( Power spectrum density ) = kt k : Boltzmann constant,t : Temperature For T=300 K N_0= -174dBm/Hz And or =1Gbps S=-84dBm is enough Modulation PAM (Amplitude) OOK (ON/OFF) PPM (Time Position) Bi-Phase arrier-less Transmission Broad banding TM-UWB (Time-Modulated) DS-UWB (Direct Sequence Phase oding) 12 13 UWB Technology Basics: Transmitting Inormation UWB Transmitter 14 15 4
UWB Receiver Unbalance in TX and RX TX is simple, and low-cost. RX is complicated due to high-speed time domain processing. Template pulse waveorm should be adaptively modiied including channel characteristics or Matched Filtering. Frequency Domain Processing Time Domain Processing Amplitude/Phase ontrol Amplitude/Delay ontrol 16 17 Matched Filter oncept Transmitting Pulse Waveorm : s( Receiving Pulse Waveorm : r(=s(+n( Filtering : Sampling and decision Optimum Filtering or Maximizing SNR H(ω)=S(ω)*exp(-ωTs) Technical Issues on Antenna and RF ircuit Wide Band Antenna Low Eiciency, Diamond Dipole,OTAB High Precision Timer (Pico second order) High Speed Multipliers, orrelators Variable Delay Line Wide Band Front-end LNA, RF BPF 18 19 5
Broadband Multipliers/Ampliiers Gilbert ell (Dierential Multiplier) Si-Ge or MOS Devices are suitable or this application. Front-end Multipliers/Ampliiers are key components. 20 21 -V haracteristics o Step Recovery Diode Pulse Generator ircuit 22 23 6
Pulse Waveorm Broad Band BPF 24 25 Transmission/Relection haracteristics Group Delay haracteristics 26 27 7
OTAB Diamond Dipole (2001, APS) 28 29 Small-size Broad Band Antenna TR Receivers 30 31 8
a t b Square (Power) Detector Multiplier? t 2 : 2 a t b t at bt 4 :SquareDetection Linear Processing 2 Intererence Problem UWB Narrow Band ommunication Systems (including GPS) 41.3dBm/MHz Allowable Radiation Power rom Electronics Equipments, e.g. P Narrow Band ommunication Systems UWB? oding Technique over Frequency Domain 32 33 hannel Modeling or UWB hannel characteristics LEAN Algorithm or lustering and Modeling Measured propagation characteristics are to be de-convolved into antennas and channel characteristics. Broad band/ High speed measurement systems are also to be developed in Frequency/ Time Domain. Fading or Shadowing? Not Frequency Flat but Frequency Selective Pulse distortion Increase o BER 34 35 9
MIMO or UWB Time Domain beam/null orming should be developed or UWB-MIMO. Delay ontrol onventional beam/null orming has been done in Frequency Domain. Phase ontrol Prototype o IR UWB Millimeter-wave Region 10 Gps Data Rate OOK Modulation 36 37 38 39 10
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48 49 onclusion UWB is a challenging theme or device/communication/signal processing researchers and engineers. High-speed and precise signal processing devices and algorithms are necessary in time domain. Nonlinearity due to large peak value should be considered. Narrow Band transmission arrier-less transmission. Frequency Domain Time Domain Processing Multiple Access Perormance o TR-UWB System Using a ombined PPM and DMPM 50 51 13
ontent Background Motivation Multi-user system or PPM-DMPM TR-UWB Receiver Simulation result and Discussion onclusion Background Ultra wide-band (UWB) technology has recently emerged as a promising candidate or high throughput short range wireless communication system. UWB system is characterized by low emission, high data rates and spectrum reuse. Frame period TR-UWB Signal T p Wireless Design Microwave engineering, March 2005 Later, Transmit-Reerence UWB (TR-UWB) approach has been envisioned as a promising eective method to avoid channel estimation. However, at least two pulses are necessary or transmitting one data bit that lead to decrease data rate o the system. Time (ns) 52 53 Motivation Other research Our research 1 st Pulse Gen Input data d(i) 2 nd Pulse Gen DTR UWB MPM TR-UWB... Switching L th Pulse Gen p 1 ( p 2 ( p L ( M bits s( X Modulation BPF N bits Delay Variable step delay By using the orthogonal pulses, the system can transmit more data during the same number o pulses. PPM DMPM PPM-DMPM or DPM More data bits can be transmitted by modulating the type, polarity and position. tr( Multi-user system or TR-UWB Time Hopping (TH) is one technique to randomizing the pulse train o UWB system. Each element o the hopping T sequence { (k) } is uniormly distributed on {0,1,2,,N u -1} in order to provide the multiple access capability T Single user Multiple access t T d p t T Td p ( ) ( s ( ) is the chip period 54 2,3, 4,1,... TR k k k k t T c d p t T c Td p ( ) ( ) ( ) ( ) ( ) ( ( k) s ( ) TR Where k c ) ( is the hopping sequence T T 55 14
Multiple access or TH-PPM-DMPM TR-UWB system Receiver r( s( h( n( T T s DMPM s DPM ( ( dd,1 p ( t T c T dd dd dd c ) (, 2,,3,...,, m1 ) dd,1 p ( t T c ( dd dd dd dd, m2,..., dd, mn1)) (,,..., ) In order to prevent interrame intererence and inter chip intererence u TH-TR UWB TH-DMPM TH-PPM-DMPM ( N 1) T T max P ( k) ( k) p( t T c ) d p( t T c T d ( k) s ( ) TR P T max T d Tmds, 2,3 T d Tmds, m1 ( N 1) T T T u Tmds P mds ( N 1) T T max u P max Tmds Tmds r( r( Auto-correlation Receiver Shit orrelation Receiver opt T delay T + delay Integrator T - opt delay Integrator For TR and PPM DTR-UWB Integrator Data decision d (i) For MPM and DMPM TR-UWB I Data decision d (i) ( i) r( t T ) r( dt ( i) I ( i) d ( i) sign ( ( i)) r( t T ) r( dt d( i) Table( I, ) c r( t T ) r( dt c c opt opt 56 57 Receiver (2) For DPM TR-UWB The number o shit correlation receiver have been used as the number o position (P) that used or modulation. ci T T T d orr corr c 1, I ( i) r( t 1 opt ) r( dt ( i) D 11 Int r( t Td ) r( dt Multi-user ( i) r( t Td ) r( dt ci Td 1,I DD 1 Int 1, ( i) r( t 1 opt ) r( dt 1, d ( i) sign ( ( i)) D 22 Int D T 2,I d(i) c A p, I ( i) r( t p opt ) r( dt Shit correlation Receiver r( DD 2 Int T ci orr 2, T c orr A ( i, ) p, ( i) r( t p opt ) r( dt I ( i, ) r ( t ) r ( t T ) dt, r ( t ) r ( t T I ci 1 ci T ) dt, ci Multi-user T ci orr corr D Pp Int ( i, ) r ( r ( t T ) dt ( i, ) r ( t ) r ( t T c i 1 c i T ) dt P,I ci DD P Int d( i,1,..., N M 1) p P, Table( 1, I, 1,,..., p, I, p, ) d ( i) Table ( I, ) 58 59...... Multi-user system or PPM-DMPM The hopping sequence and chip period have to be considered in the receiver. Auto-correlation Receiver 15
Simulation Speciication Pulse Modulation Gaussian and Rayleigh monocycle PPM and DPM Pulse period 0.5 ns hip period 1-20 ns Frame period 10-400 ns Number chips per rame (Nc) 10, 20 Filter Bandpass (3.1-10.3 GHz) hannel S-V model with NLOS 1-4 m (M2) BER 10 0 10-1 10-2 Simulation result and Discussion (1) BER when rame period = 100 ns TR, 1user 10-3 PPM PPM DMPM 5 users 10-4 TR, 5 users PPM PPM DMPM 10-5 TR, 10 users PPM 1 user PPM DMPM 10-6 10 12 14 16 18 20 22 24 26 28 E b /N o (db) 10 users By using PPM-DMPM, the system The error loor has occurred in all o the decrease the required E b /N 0 by 4-6 db. system when the number o user increased. For 5 users case, the error loor has MAI (Multiple Access Intererence) dominates occurred in case o short rame period, 100 the perormance as the number o user ns (let graph). increase. 60 BER 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 BER when rame period = 300 ns TR,1 user PPM MPM PPM DMPM TR,5 users PPM MPM PPM DMPM TR,10 users PPM MPM PPM DMPM 1 user 6 8 10 12 14 16 18 20 22 24 E b /N 0 (db) 10 users 5 users 61 Throughput (Mbps) 10 9 8 7 6 5 4 3 2 1 Simulation result and Discussion (2) Throughput perormance when rame period = 300 ns TR, 1 user PPM PPM MPM PPM DMPM TR, 10 users PPM PPM MPM PPM DMPM 0 2 4 6 8 10 12 14 16 18 20 E b /N o (db) PPM-MPM and PPM-DMPM can achieve its maximum throughput at E b /N 0 o about 16-18 db. PPM-MPM and PPM-DMPM can provide better throughput perormance than conventional system. Especially, PPM-DMPM needs the lower required E b /N 0 than PPM- MPM about 2 db. Simulation result and Discussion (3) This result shows the system capacity with BER (error loor) = 10-3. Total throughput perormance in both case o proposed systems are better than conventional system. Throughput characteristic o all system are similar to each other because o using the PPM-DMPM can provide more system capacity than other TR-UWB in both o single user and multiple access system because o more transmitted data bits per rame. same multiple access. 62 63 16
onclusion By using SR, the proposed system can achieve the excellent error and total throughput perormance o the system. When rame period has become longer, although the error perormance has been improved, the maximum data rate o the system will be decreased. By using the proposed system, PPM-DMPM TR-UWB, more total throughput has been achieved, e.g. TR-UWB PPM PPM-DMPM For single user 70 Mbps 115 Mbps 240 Mbps For multi-users 40 Mbps 85 Mbps 185 Mbps 64 17