Ultra Wideband Radio Channel Resource Allocation Strategies

With the characteristics of simple system architecture, low cost and small power consuming, Impulse Radio (IR) Ultra Wideband (UWB) technology becomes popular in recent years. IR-UWB is the same with very short distance wireless network. But existing UWB networks and studies always adopt center-controlled architecture. However, the studies on UWB network with distributive architecture are rarely, so more studies need to be taken on the wireless access control and channel resources sharing of distributive architecture network. All the existing MAC protocols, neither IEEE 802.11 which applied to WLAN nor IEEE 802.15 which applied to WPAN, can not use wireless channel resources efficiently. Based on the physical characteristics of UWB, it's important to design a more optimum UWB distributive architecture MAC protocols, which can optimize channel resources allocation and improve throughput with low cost.In view of above issues, this paper point out the differences between IR-UWB, DS-UWB and MB-OFDM UWB, and analyses their advantages and disadvantages. Finally, based on the IR-UWB of simple architecture, low cost, Analyzing the UWB MAC designing principle and functions, and including multi channels access, resource sharing, and access control administration and so on. In order to distinguish the multi user channels, using the Time-Hopping sequence to control the transmission of pulse. And this paper proposed common-private time-hopping allocation method which adopts handshake protocol. Based on the different links (DB link or RB link), this paper proposed a series of resources allocation algorithm to improve and perfect the resources allocation policies.Based on the resources allocation algorithm, this paper proposes a TH-IR based Rate-Adaptive Time Hopping (RATH) MAC protocol with a guarantee of bit error rate and transmission rate provision. The RATH protocol uses common-private method to allocate time hopping code, and finally form multi-users channel access mechanism. According to Signal-to-Interference-and-Noise ratio (SINR) of receiver, RATH determines establishment of each link, which has a variable transmission rate adjusted by the Rate-Adaptive algorithm. And use efficient ACK mechanism to transmit data. Simulation experiments via NS2 show that RATH is able to significantly enhance performance of the network effective throughputs and transmission delay, with respect to TH-IRUWB MAC protocols.