Ultra Wide Band And Its Applied Research In Ad Hoc Networks

Ultra wideband (UWB) communication is a novelshort-distance wireless communication technique, in which dataare transferred using impulses with very short duration. It hasmany advantages, such as high transmission rate, low powerconsumption, good security, highly accurate positioningcapability and low cost. With the approval of FCC, there areincreasing interests in studying UWB technologies in bothacademia and industry.An ad hoc network is a self-organization wireless networkwith no fixed infrastructure, therefore, each node has adistributed algorithm and it id essential to use multi-hoptransition. For ad hoc network, the UWB is particularlyattractive due to its highly accurate positioning capabilitieswhich can forecast the topology of network, low transmissionpower which can reduce node's battery power consumption, etc.In a word, UWB Ad Hoc network will have better networkcapability and better security capability.Firstly, the paper reviews the principles of impulse-basedUWB communication system, analyses DS-UWB transceivers' modeland power spectrum density. Introduces the key technologies ofUWB, such as channel model, pulse mode, medium access control(MAC), ranging and positioning. Secondly, some classic MACprotocols are introduced and an on-demand synchronization codedivision multiple access (ODS-CDMA) protocol for the mobile adhoc network is proposed. The protocol establish the temporarysynchronization between the sending node and receiving nodeonly when they are communicating, which combine the strong points of the synchronization and asynchronization MACprotocol. The slot reservation and power control are integratedwith CDMA to improve the network performance. Finally, usechaotic sequences and adjustment factor to reduce the multipleaccess interference (MAI), increase the system capacity.Finally, a DS-UWB communications system based on chaoticspread spectrum sequences is presented. Synchronization andsecurity is developed according to the characteristics of thecommunication system, and a SDR realization is given.