BAN MAC protocol for optimization the ratio between CAP and CFP

Abstract

Recently, a micro or nano size wireless telecommunications device such as a wireless implant capsule endoscope has been researched and developed. These wearable and implanted wireless devices are quite useful to remotely monitor various vital information, for example ECG, EEG, etc. And we use manipulators for medical treatment. In order to connect several medical sensors and actuators in and on human body, wireless body area network (BAN) has been developed. However, wireless radio communications in BAN may occur a large variance of transmission delay due to complicated radio propagation in and on body. In addition, a lot of packets are coming with contention against each other. The large variance of delay may cause a serious problem in remote medical treatment. Therefore medical packets must be guaranteed about the delay and the authenticity. In particular, emergency access packets should be guaranteed a largest delay within a permissible range. On another front, communication efficiency of non-medical packets has to be guaranteed as much as possible. A MAC protocol using hybrid structure of super frame in IEEE802.15.6 has been proposed. However, a ratio between CFP and CAP in a super frame has not been determined in the standard yet. This paper investigates how to determine the ratio according to traffic of medical and non-medical packets. After calculating the best length of CFP by the medical traffic, non-medical information is allocated in CFP as much as possible. In so doing, the total throughput is improved after securing the delay of medical information. Moreover as for traffic monitoring, we proposed the slotted aloha plotocpl for using the different transmition timing as to the priority of packets. The utility of the method was evaluated by computer simulation. On the proposed method, throughput of medical packets is nearly equal to being allocated CFP to upper limit, and non-medical throughput is better than fixed slots method. Therefore, total throughput is improved. And the accuracy of traffic estimation is good performance for using proposed determining the ratio of CAP and CFP slots.