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Applications of wearable and implanted wireless sensor devices are hot research area. A specialized field called the body area networks (BAN) has emerged to support this area. Managing and controlling such a network is a challenging task. An efficient media access control (MAC) protocol to handle proper management of media access can considerably improve the performance of such a network. Power consumption and delay are major concerns for MAC protocols in a BAN. Low cost wakeup radio module attached with sensor devices can help reduce power consumption and prolong the network lifetime by reducing idle state power consumption and increasing sleep time of a BAN node. In this article, we propose a new MAC protocol for BAN using out of band (on-demand) wakeup radio through a centralized and coordinated external wakeup mechanism. We have compared our method against some existing MAC protocols. Our method is found to be efficient in terms of power consumption and delay.

The present study is conducted to analyze the potential of SMEs in the economy of Bangladesh. Data were collected from 100 SME units by using simple random technique. A structural questionnaire was developed to get the responses from different SME units in the country. For Bangladesh SMEs have assumed special significance for poverty reduction programmes and potential contribution to the overall industrial and economic growth. Some of the constraints related SME financing are identified and some pointers for the future are provided through the study.

SUMMARYThe IEEE 802.15.4K Task Group was formed recently to address the low energy critical infrastructure monitoring networks. The aim is to collect scheduled and event data from a large number of non-mains powered endpoints that are widely dispersed. The application requirements include reliable data transfer, energy efficiency, and long deployment lifetime. To meet the low energy critical infrastructure monitoring network requirements, we propose a multihop medium access control protocol where the scheduled or event data are routed to the coordinator through the cluster heads. The power consumption of the cluster heads is critical as they use more power than the normal endpoints. Our protocol uses the wake-up radio approach from cluster head to cluster head communication and an efficient guaranteed time slots allocation scheme to minimize the power consumption of the cluster heads. We derive analytical expressions for the average power consumption of cluster heads as well as ordinary endpoints. The results show that our proposed protocol outperforms the IEEE 802.15.4 MAC and SCP MAC in terms of power consumption. High power efficiency is achieved in both the cluster heads and normal endpoints.

The present study is conducted to analyze the potential of SMEs in the economy of Bangladesh. Data were collected from 100 SME units by using simple random technique. A structural questionnaire was developed to get the responses from different SME units in the country. For Bangladesh SMEs have assumed special significance for poverty reduction programmes and potential contribution to the overall industrial and economic growth. Some of the constraints related SME financing are identified and some pointers for the future are provided through the study.

The IEEE 802.15.4 standard is a short range wireless technology. As a revision to this standard, IEEE 802.15.4a introduces new options for PHY (physical layer) to enable ranging. In this paper, we investigate the theoretical maximum throughput and minimum delay of the un-slotted version of 802.15.4a using CSS (Chirp Spread Spectrum) PHY. The throughput and delay limits are derived for different frequency bands and data rates along with the formulae. Moreover, we calculate the bandwidth efficiency for both the standards. The comparative analysis concludes that the performance of 802.15.4a surpasses 802.15.4 in terms of throughput and delay.

SUMMARYRecently, the IEEE TG4k has been formed to amend the IEEE 802.15 family to address the low energy critical infrastructure monitoring networks. The purpose is to facilitate point to multi‐thousands of point communication to collect the scheduled and event data from a large number of nonmains powered endpoints that are widely dispersed. It should support low energy operation, which is necessary for multiyear battery life. Other major features are application data rate up to 40 Kb/s, thousands of endpoints per mains powered infrastructure, asymmetric application data flow, small and infrequent messages, tolerant to data latency, etc. In this paper, we present a discussion on low energy critical infrastructure monitoring networks. We propose a medium access control protocol based on framed slotted aloha for these networks. We investigated probable packet sizes, energy consumptions, battery lifetime and the success rate for our protocol. The proposed protocol is simple to implement. Simulation results show that it is efficient in terms of packet success rate, energy consumption, and battery lifetime.Copyright © 2012 John Wiley & Sons, Ltd.

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