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SDR and UWB

SDR and UWB. By : Ahmad Bakhtafrouz. What is UWB?. FCC Definitions. UWB Signaling. - Impulse Radio. UWB Advantages. UWB Challenges. UWB Applications. Modulation Types. - Single-carrier-based Modulation. - OFDM-based Modulation. Multiple Access. IEEE 802.15.3a.

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SDR and UWB

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  1. SDR and UWB By : Ahmad Bakhtafrouz

  2. What is UWB? • FCC Definitions • UWB Signaling - Impulse Radio • UWB Advantages • UWB Challenges • UWB Applications • Modulation Types - Single-carrier-based Modulation - OFDM-based Modulation • Multiple Access • IEEE 802.15.3a - Direct Sequence UWB - Multi-band OFDM • SDR and UWB • SDR UWB Solution

  3. What is UWB?

  4. The IEEEXplore History of UWB :

  5. FCC Definition :

  6. FCC Definition : UWB Spectral mask :

  7. FCC Definition :

  8. UWB Signaling :

  9. Impulse Radio : • Pulse shapes : • Gaussian , Hermetian families

  10. UWB Advantages : • Ability to share the frequency spectrum • coexistence of UWB signals with narrowband and wideband signals • in the RF spectrum • Large channel capacity

  11. UWB Advantages : • Ability to work with low SNRs • the shannon formula indicates that the channel capacity is only • logarithmically dependent on SNR. • Low probability of intercept or detection • because of their low average transmission power , UWB systems • have an inherent immunity to detection and interception. • Resistance to jamming • no jammer can jam every frequency in the UWB spectrum at once.

  12. UWB Advantages : • High performance in multipath channel

  13. UWB Advantages : • Superior penetration properties • the low frequencies included in the broad range of UWB frequency • spectrum have long wavelength, which allows UWB signals to • penetrate a variety of materials. • Simple tranceiver architecture

  14. UWB Challenges : • Pulse shape distortion • the received signal power will decrease quadratically. • Channel estimation • High-frequency synchronization • very fast ADCs required. • Short range • low transmission power.

  15. UWB Challenges : • Multiple access interference • detecting the desired user’s information is more challenging • than in narrowband communication.

  16. UWB Applications : • Wireless communication systems • Short range radios • Home networking / PAN • Roadside info-station • Military communications • Wireless sensor networks • High-resolution RADAR and sensing • vehicle RADAR • see-through-the-wall (police,fire,rescue) • Medical imaging • Ground penetrating RADAR • Surveillance • Location finding • Position location • RFID

  17. Modulation Types : • Single-carrier-Based Modulation : • Time-Hopping PPM • Amplitude Modulation • Orthogonal Pulse Modulation (OPM) • Pseudochaotic TH-PPM

  18. Modulation Types : • OFDM-Based Modulation : • The UWB frequency band is divided into multiple smaller bands • with bandwidths greater than 500 MHz.

  19. Multiple Access : • FDMA : • Smaller bands must be greater than 500 MHz. • TDMA : • Synchronization becomes more difficult and complicate. • CDMA • OPMA (Orthogonal Pulse Multiple Access) - The multiple access channel will achieve full user capacity when the number of users Nu< 15, and when the number of users is greater, user capacity will decrease.

  20. Multiple Access :

  21. IEEE 802.15 :

  22. IEEE 802.15 :

  23. IEEE 802.15.3a : • March 2003: more than 30 proposals were submitted to TG3a • 7 proposals was chosen initially • After “down selection procedure”, 2 merged proposals left: Direct Sequence Ultra Wideband (DS – UWB) & Multi-Band OFDM (MB-OFDM)

  24. DS-UWB :

  25. MB-OFDM :

  26. Overview of Proposals:

  27. SDR and UWB : • Benefits of SDR for UWB : 1 ) Reduce the development cycle and time-to-market • 2 ) As UWB aims at answering many needs, it may also be implemented in many flavors. Hence it would naturally gain a great benefit in supporting SDR features . 3 ) The SDR approach may also be a catalyst for new ideas and applications around UWB, thanks to its intrinsic scalability and mutability properties. At least could it permit to provide systems with adaptability features .

  28. SDR and UWB : • Benefits of SDR for UWB : 4 ) DS-CDMA and OFDM are sources of strong oppositions and SDR is foreseen as a solution to accommodate the different proposals . It might not make those different systems compatible, but could at least make them co-exist on the same hardware. 5 ) Ad-hoc networking is also considered as one of UWB's great impacts. In this context, UWB systems could be adapted to support some network responsibilities through SDR techniques. Each corresponding configuration could be directly dimensioned depending on the context of ad-hoc networking really needed. This is more flexible than preinstalled general purpose configurations that are either overdimensioned or too weak.

  29. SDR and UWB : • Challenges of SDR for UWB : 1 ) Large bandwidths which demands very high sampling rates . 2 ) Power consumption 3 ) Cost

  30. SDR and UWB : • Necessity to reorient SDR for UWB : • Digitalizing the bandwidths of several GHz results extra cost . • Using the SDR analog front-end to do as much of the processing a • possible so a narrower bandwidth digitization becomes possible

  31. SDR and UWB : • Necessity to reorient SDR for UWB : - Passive analog front-end (low cost and low power consumption). - Easy-to-integrate. - Pre-processing that only extracts the necessary metrics. - Adequate bandwidth for low-cost ADCs and realistic digital processing speed. - Relaxed synchronization means. - Multiple usage of the same RF front-end output for several applications managed by SDR. - Multiband support for high data rates (each band having convenient characteristics for SDR capabilities) in a way that allows for parallelization of the subsequent digital processing.

  32. SDR and UWB : • Non-coherent elementary receiver : • thus a receiver working as an energy detector, information is preferably carried • by signal amplitude rather than its phase. • it leads us to consider pulse amplitude modulation (such as OOK). • Relaxed channel estimation • Suitable signal processing • Simple hardware architecture • Only approximate delay spread and energy levels are needed

  33. SDR UWB solution: • General points : • To increase the system capacity while preserving these properties, we propose • to duplicate this basic scheme on several separate subbands (in practice from • eight to 24 bands of 250 to 500 MHz each). • Each band must only keep sufficient wideband characteristics to provide the • receiver with enough multipath to benefit from the diversity offered by the • channel . • only a coarse synchronization is needed (an error of 2 ns << Ti = 40 ns is • acceptable), which makes the system robust against the clock jitter and every • triggering inaccuracy. • Because the processing is based on energy, the transceiver performances are • nearly insensitive to distortion and phase non-linearities of device. • low-power consumption is achieved, thanks to the use of mainly analog and passive • devices.

  34. SDR UWB solution: • Transmitter : • Bank of filter • Bank of local oscillator (coherence is not required) • An interesting feature to notice here is that the architecture permits a simple power control in each • sub-band. This kind of flexibility can be useful to fulfill a regional power spectral density mask.

  35. SDR UWB solution: • Transmitter : All the components requires are available on the shelves. We have two problems : 1- Wideband antenna 2- Insertion loss of switches

  36. SDR UWB solution: • Receiver : • The integrators have to be able to integrate these signals over a time period of 10 to 50 ns. • With advances in process technology, it is possible to integrate both these functions on • a single chip.

  37. SDR UWB solution: • Results : • As a conclusion, the proposed architecture for high data rates only requires a simultaneous • digitization on each sub-band (24 as an example) at a rate of a several tens of megahertz • with a resolution of one to a few bits. • Indeed, comparison with coherent systems show that, to compete with our on-off keying • scheme, a classical rake receiver for a coherent BPSK should collect up to 40% of the • whole available energy. This is challenging due to severe multipath characteristics for • typical UWB impulse radio signals and should hardly be achievable at the same cost of the • solution proposed in this article.

  38. References : 1 - “ RF Front-End Considerations For SDR Ultra-wideband Communications systems” By Stéphane Paquelet , Christophe Moy and Louis-Marie Aubert 2 - “ A SDR Ultra-Wideband Impulse Communication System For Low And High Data Rates “ Christophe Moy - Ph.D, Stéphane Paquelet,Alexis Bisiaux - Ph.D., Apostolos Kountouris - Ph.D 3 - Ultra wideband wireless communications and networksX. shen , M. Guizani , R.C. Qiu , T. Le-Ngoc 4 - Several slides from : • Ultra wideband communications past,present,future by : chris snow • Ultra wideband applications and technologies by : nathania august • Ultra wideband radio design by : lawrenc williams

  39. Thank you for your attention! Questions?

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