The Sensor Proxy Mobile IPv6 (SPMIPv6) has been designed for IP-based wireless sensor networks mobility to potentially save energy consumption by relieving the sensor nodes from participating in the handoff process. However, SPMIPv6 is dependent on a single and central Local Mobility Anchor (LMA), and thus, it inherited most of the problems observed in the Proxy Mobile IPv6 (PMIPv6) protocol, including long handoff latency, non-optimized communication path, and bottleneck issues. In addition, SPMIPv6 extends the single point of failure to include both the authentication and network information. This study presents an enhanced architecture for SPMIPv6 called Clustered SPMIPv6 (CSPMIPv6) to overcome the problems above. In the proposed architecture, the Mobility Access Gateways (MAGs) are grouped into clusters, each with a distinguished cluster Head MAG (HMAG). The HMAG is mainly designed to reduce the load on LMA by performing intra-cluster handoff signaling and providing an optimized path for data communications. The proposed architecture is evaluated analytically, and the numerical results show that the proposed CSPMIPv6 outperforms both SPMIPv6 and PMIPv6 protocols in terms of LMA load, local handoff delay, and transmission cost performance metrics.

The provision of resources and services for scientific workflow applications using a multi-cloud architecture and a pay-per-use rule has recently gained popularity within the cloud computing research domain. This is because workflow applications are computation intensive. Most of the existing studies on workflow scheduling in the cloud mainly focus on finding an ideal makespan or cost. Nevertheless, there are other important quality of service metrics that are of critical concern in workflow scheduling such as reliability and resource utilization. In this respect, this paper proposes a new multi-objective scheduling algorithm with Fuzzy resource utilization (FR-MOS) for scheduling scientific workflow based on particle swarm optimization (PSO) method. The algorithm minimizes cost and makespan while considering reliability constraint. The coding scheme jointly considers task execution location and data transportation order. Simulation experiments reveal that FR-MOS outperforms the basic MOS over the PSO algorithm.

Cloud computing is an innovative technology that deploys networks of servers, located in wide remote areas, for performing operations on a large amount of data. In cloud computing, a workflow model is used to represent different scientific and web applications. One of the main issues in this context is scheduling large workflows of tasks with scientific standards on the heterogeneous cloud environment. Other issues are particular to public cloud computing. These include the need for the user to be satisfied with the quality of service (QoS) parameters, such as scalability and reliability, as well as maximize the end-users resource utilization rate. This paper surveys scheduling algorithms based on particle swarm optimization (PSO). This is aimed at assisting users to decide on the most suitable QoS consideration for large workflows in infrastructure as a service (IaaS) cloud applications and mapping tasks to resources. Besides, the scheduling schemes are categorized according to the variant of the PSO algorithm implemented. Their objectives, characteristics, limitations and testing tools have also been highlighted. Finally, further directions for future research are identified.

Transmission control protocol (TCP) performance over multi-hop wireless networks is currently attracting considerable interest from the research community. The characteristics of multi-hop wireless networks, such as mobility, link layer contention, high bit error rate, asymmetric path, network partition, hidden exposed nodes and dynamic routing, do not fit the requirements of TCP for a good reliable data delivery. Here we want to provide an overview of the research progress in applying TCP algorithms to the problem of multi-hop conditions and characteristics. The scope of this review will encompass core methods and protocols of TCP over multi-hop networks, including cross-layer, network layer protocols and medium access control (MAC) layer protocols. The research contributions in each field are systematically summarized and compared, allowing us to clearly define existing research challenges, and to highlight promising new research directions. The findings of this review should provide useful insight into current multi-hop networks literature and be a good source for anyone who is interested in "TCP in wireless" approaches or related fields.

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The main goal of the IEEE 802.11n standard is to achieve more than 100Mbps of throughput at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. A key enhancement is frame aggregation which reduces the overheads and increases the channel utilization efficiency. The MAC layer defines A-MSDU and A-MPDU frame aggregations in which MAC overheads are squeezed by aggregating multiple frames into a single large frame before being transmitted. As a consequence of the aggregation, new aggregation headers are introduced and become parts of the transmitted frame. The existence of such headers will have a negative impact on the performance, especially when aggregating frames of small payloads. In this paper, we have analysed the aggregation headers of the 802.11n aggregation schemes and introduced an MSDU frame aggregation that reduces the header's overhead and supports the applications that have a small frame size such as VoIP.

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