An Adaptive IEEE 802.15.4a TH-TDMA UWB Industrial Field Level Network

Abstract

We introduce the deployment of IEEE 802.15.4a in industrial field level communication, which is unexplored so far. Impulse radio-time hopping ultra wide band (IR-TH UWB) physical layer is robust against dense multipath fading and interferences. However, we propose an adaption in medium access control (MAC) to meet the major constraints of reliability and timeliness. The self configuring MAC overcomes the difficulties and limitations of specified carrier sense multiple access/collision avoidance (CSMA/CA), slotted Aloha and guaranteed time slots (GTS) mechanisms. Addressable TH codes in fixed time slots of modified superframe structure are used to handle asynchronous alarm requests during ongoing synchronous transmissions. Traffic modeling is presented and we derive the expressions for accessing delays of both the synchronous and asynchronous data traffics. The realistic industrial non line of sight (NLOS) channel environment of IEEE 802.15.4a is employed and the respective power delay profile (PDP) and cumulative density function (CDF) of instantaneous signal to noise ratio (SNR) are found. Moreover, for large number of resolvable multipath components (MPCs), we also propose a reduced complexity adaptive SRake receiver, which efficiently recovers the weak IR-TH UWB signals in dense multipath propagation and strong noise. In addition, we evaluate the error performance of the proposed receiver architecture in comparison with conventional SRake and additive white Gaussian noise (AWGN) correlation receivers. Our simulation results show a significant performance improvement with very less number of SRake fingers.