We introduce distributed algorithms for the RFID coverage problem, which is defined as finding the minimum amount of RFID readers that cover every tag. The algorithms depends on rounds of writes and reads in/from the tags' memories. The first algorithm, called Greedy Distributed Elimination (GDE), is inspired of, and equivalent to, the greedy approximation algorithm of the set cover problem. Our second contribution is a randomized algorithm that can run in one or more write/read rounds (called RANDOM and RANDOM+). Using concepts concluded from these algorithms, we introduce algorithm GDE-RANDOM+ which improves further the number of non-redundant readers of GDE by integrating it with RAN-DOM+.

In this paper, we have proposed a dynamic IP address assignment architecture for wireless heterogeneous sensor networks. The assignment scheme and the architecture guarantee that communication channels can be assigned only between the registered devices ensuring the security. The dynamic IP address assignment scheme is based on the advertisement of the IP address utilization status at the base stations. Thus, each base station advertises its IP address utilization database when the ratio of the negative acknowledgement messages received from the DNS exceeds a certain threshold. By simulations, we have shown that the proposed assignment scheme introduces significant enhancement in terms of blocking probability when compared to an approach where each base station has its own IP address pool. Furthermore, we have defined three types of blocking, the real blocking, the unjustified acceptance and the unjustified rejections. We have seen that the proposed scheme can lead to lower blocking probability compared to the uniform IP assignment as long as the update threshold is kept below 1.5%.

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SUMMARYIn this article, we propose a dynamic Internet Protocol (IP) address assignment architecture for heterogeneous wireless IP devices network. The IP device could be a sensor device, a laptop, a cell phone, or any wireless device using IP communications. The proposed architecture introduces security and service reliability to the consumer while reducing the operational expenditure for the service providers. According to the proposed scheme, each node maintains an IP address pool storing the current occupancy of each IP address. Each node advertises its database whenever the ratio of negative acknowledgments from the domain name server to the total number of requests at a given node exceeds a certain threshold. We evaluate our IP assignment scheme under two traffic intensity scenarios, namely the uniform traffic intensity and the heterogeneous traffic intensity. Performance evaluation is carried out with respect to blocking probability and average IP list utilization. We define three types of blocking probability for the user requests as follows: The real blocking, the unjustified acceptance, and the unjustified rejection. We observe that the proposed scheme outperforms the uniform assignment as long as the threshold is below 1.5% for the uniform intensity scenario and 1% for the heterogeneous scenario. Furthermore, this architecture considers the security aspect of the wireless network by allowing only registered devices to communicate with other registered devices. Copyright

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