Novel modulation adaptation techniques for IEEE 802.15.4a UWB system

Wireless monitoring systems are envisioned to reduce healthcare costs and improve the efficiency of treatment of patients in future health care systems. Before transmissions of vital biomedical information over wireless channel can be fully exploited, effective and reliable solutions are required in the medium access control (MAC) and physical (PHY) layers. Furthermore, cross-layer operation of the above-mentioned layers should be optimized to maximize the overall system performance. In this paper, we introduce novel modulation adaptation techniques between MAC and PHY layers of a single sensor node and furthermore, between PHY layers of multiple sensor nodes. By utilizing the proposed techniques, modulation method of IEEE 802.15.4a UWB (ultra wideband) system can be dynamically changed based on, e.g., required Quality of Service (QoS) or channel information. A comparative performance analysis between the original IEEE 802.15.4a UWB system and a system utilizing the proposed methods is presented in a wireless hospital environment. Based on the analysis it can be stated that the overall system performance is increased in terms of throughput and packet delivery ratio and average data packet delay is halved, when the proposed techniques are utilized.