An adaption of IEEE 802.15.4a in an industrial Field Bus

Low data rate, IEEE 802.15.4a wireless personal area networks (WPANs) are introduced in industrial field level communication. The standard supports a carrier less baseband impulse radio-time hopping ultra wide band (IR-TH UWB) physical layer (PHY), which due to its small duty cycle and very short pulse widths is robust against dense multipath propagation and interferences. The medium access control (MAC) allows the use of slotted Aloha, carrier sense multiple access/collision avoidance (CSMA/CA) and guaranteed slots (GTS) mechanisms. However, for its efficient deployment in Field Bus systems, an adaption is required to improve reliability and real time performance. We propose a self configuring MAC to handle asynchronous alarm requests during ongoing synchronous transmissions. Addressable TH codes in fixed time slots of modified superframe structure are employed. On behalf of these amendments, expressions for accessing delays of synchronous and asynchronous data are derived with traffic modeling. In addition, the error performance of the selected PHY is evaluated over realistic IEEE 802.15.4a industrial non line of sight (NLOS) channel in comparison over additive white Gaussian noise (AWGN). Selective Rake (SRake) receiver is used to recover the signal in dense multipath propagated environment. Impulse response and the power delay profile (PDP) of the channel are generated and presented.