Performance analysis of low rate wireless technologies for medical applications
Computer Communications
Bluetooth and WLAN coexistence: challenges and solutions
IEEE Wireless Communications
IEEE Transactions on Information Technology in Biomedicine
Prevailing over wires in healthcare environments: benefits and challenges
IEEE Communications Magazine
IEEE Communications Magazine
FSA: a fast coordination scheme for opportunistic routing
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Hi-index | 0.00 |
Complementary WLAN and WPAN technologies as well as other wireless technologies will play a fundamental role in the medical environments to support ubiquitous healthcare delivery. This paper investigates clear channel assessment (CCA) and its impact on the coexistence of WLAN (IEEE 802.11 high rate direct sequence spread spectrum (HR/DSSS) PHY) andWPAN (IEEE 802.15.4b) in the 2.4 GHz industrial, scientific, and medical (ISM) band.We derived closed-form expressions of both energy-based CCA and feature-based CCA. We qualified unequal sensing abilities between them and termed this inequality asymmetric CCA, which is different from the traditional "hidden node" or "exposed node" issues in the homogeneous network. The energy-based CCA was considered in the considered integratedmedical environment because the 2.4 GHz ISM band is too crowded to apply feature-based CCA. The WPAN is oversensitive to the 802.11 HR/DSSS signals and the WLAN is insensitive to the 802.15.4b signals. Choosing an optimal CCA threshold requires some prior knowledge of the underlying signals. In the integrated medical environment we considered here, energy-based CCA can effectively avoid possible packet collisions when they are close within the "heterogeneous exclusive CCA range" (HECR). However, when they are separated beyond the HECR, WPAN can still sense the 802.11 HR/DSSS signals, but WLAN loses its sense to the 802.15.4b signals. The asymmetric CCA leads to WPAN traffic in a position secondary to WLAN traffic.