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Mobile commerce is considered an excellent alternative for enterprises to reach new customers. However, many mobile commerce websites have a short life because they donpsilat meet the userspsila requirements. This paper presented the consumer-oriented criteria for mobile commerce website evaluation and developed a model, including four dimensions: mobile web site quality, enjoyable shopping experience, service quality, and trading risk. This study utilized an evaluation approach based on fuzzy set theory and the technique for order performance by similarity to ideal solution (TOPSIS) to determine overall performance value and rank of the mobile commerce websites, using triangular fuzzy numbers to express linguistic variables that consider the subjective judgments of evaluators and applying fuzzy multiple criteria decision-making approach to synthesize the group decision. Finally, several suggestion and future research are discussed.

Former Media Access Control (MAC) protocols for Wireless Sensor Networks (WSNs) are mainly for static networks. In the networks where mobile nodes exist, the performance will degrade greatly. In this paper the performance of MAC in mobile WSNs (mWSNs) is analyzed and improved algorithms are presented. Simulations validate the effects. A new MAC protocol also is presented for the scenario with more mobile nodes.

Many media access control (MAC) protocols for wireless sensor networks (WSNs) such as sensor MAC (S-MAC) and carrier sense multiple access with minimum preamble sampling (CSMA-MPS) exploit listen/sleep cycles to conserve energy. The cycles of nodes influence the network performances such as energy efficiency, packet latency and throughput in WSNs. In this paper, an adaptive schedule medium access control (AS-MAC) for WSNs is presented. AS-MAC introduces the adaptation of the cycles in MAC layer to the data traffic. The effect of the protocol is that it can decrease the latency, improve the throughput and energy efficiency when traffic is dynamic. We also compare AS-MAC with S-MAC and CSMA-MPS through simulations and the results show it has better performances than the former protocols.

This paper presents a contention-based Medium Access Control (MAC) protocol, Synchronized Sensor Medium Access Control (SS-MAC), for wireless sensor networks (WSNs). To solve the high energy consumption problem in boundary nodes between virtual clusters in Sensor-MAC (S-MAC), SS-MAC introduces the global synchronization of schedules in WSNs. The novelty of our protocol is that it can improve the connectivity of WSNs compared with S-MAC. We illustrate the efficiency and scalability of the scheme via simulation

In this paper, the influence of correlated data from different sensors on the location of the sensors and the consumed energy of wireless sensor network are introduced, and the performance of a joint entropy encoding strategy which compresses the correlated data along routing is analyzed. During transmission, relay sensors jointly encode their own sampled data and the data received from upward sensors. The consumed energy of the network is minimized through optimally choosing the location of sensors. For the sake of prolonging network lifetime, a scheme to balance the consumed energy between different sensors is proposed, which combines the correlation between data and the amounts of data transmitted by different sensors, to make the transmitted energy consumed by different sensors tend to be uniform by adjusting the distance between sensors. The applications of the schemes in one-dimensional wireless sensor network are presented and the numerical results show that these schemes have excellent performance.

In a multi-service network in which multiple classes with different priorities and different QoS requirements exist, preemption is an efficient mechanism for bandwidth allocation and management. By considering preemption-related information in the path selection procedure, we can minimize rerouting and improve network stability. In this paper, we propose a preemption-aware bandwidth-constrained path selection algorithm for DiffServ-enabled MPLS networks. The basic idea is that the available resource reservation information of lower priority LSPs, i.e. the bandwidth to be preempted and the affected highest priority level, is introduced in the path selection. Simulations show that our proposed algorithm can achieve preemption minimization as well as load balancing, and efficiently improve overall network performance.

This paper introduces three hierarchical mobile IP schemes, i.e. hierarchical mobile IP (HMIP), dynamic HMIP, and distributed and dynamic HMIP to improve the handoff performance, and develops a model for cost analysis based on one-dimensional random walk of mobile host. Then the paper compares signaling transmission cost, packet delivery cost and total cost of the three schemes respectively, and discusses the effects of different home handoff thresholds and directional walk probabilities on these costs. Numerical results show that the DHMIP scheme has best performance among the three under small home handoff threshold.

The issue of TCP performance over wireless link and the related work are introduced. A new scheme is proposed to improve TCP performance over wireless link in the direction from mobile host to wired network. It deploys a TCP agent at the base station to monitor the segments related to the mobile host, and then triggers TCP fast retransmission on mobile host side by replicating and forwarding specific ACKs, which can effectively avoid timeout retransmission. Simulation results show that the new scheme has favorable performance.

The TCP performance issues in bandwidth asymmetric network are investigated. Some related works to improve TCP performance are introduced and analyzed. A scheme using SACK filtering to enhance the TCP performance in bandwidth asymmetric network is proposed. An advanced SACK filtering scheme is introduced, which can further improve TCP performance by decreasing the size of block information in SACK option. Simulation results show that the new schemes have better performance.

This paper introduces RSVP, MRSVP and the QoS guarantee mechanism in mobile IP by utilizing the MRSVP. Three HMRSVP schemes are described and compared in detail, especially the HMRSVP with pointer forwarding. A modified one is proposed. In this scheme, MH in a hierarchical region uses pointer forwarding scheme, which can utilize the feature of movement locality. When it moves into a new region, it is required to update the RSVP path and begin the new pointer forwarding process. Also, the feature of locality is discussed thoroughly. The modified scheme is modeled and analyzed in two different cases. The results show that it has better performance. Finally, future work is illustrated.

In this paper the mobile IP and its handoff issues are introduced. Three main factors that affect mobile IP's handoff performance, mobility detection, re-registration, interaction with higher layer protocols, are analyzed thoroughly. Some new schemes are proposed. A new option is proposed and is added into foreign agent advertisement message. The option contains the link layer identifiers of all the links managed by that foreign agent. Then mobile host can determine whether a mobile IP handoff is required or not soon after the link's layer handoff. So the mobile IP handoff can be accelerated and unnecessary handoffs can be avoided. When mobile host is the TCP sender, it is proposed to send all the unacknowledged segments soon after the handoff, so as to prevent TCP timeout retransmission; when mobile host is the TCP receiver, it sends several TCP SACKs to trigger the senders fast retransmission of lost segments. The implementations of the new proposals are also outlined. At last, all the new schemes are simulated and the results show that through these schemes, the performances of mobile IP handoff are improved significantly.

The mobile host's mobility has much influence on the implementation of multicast in Mobile IP. At first two basic schemes, i.e. bi-directional tunneling and remote subscription are introduced. Then two related schemes are introduced and analyzed. After that a new scheme is proposed. It introduces mobile multicast gateway (MMG) to manage mobile multicast. MMG can obtain the multicast packets by adding itself onto the multicast distribution tree, or through the tunnel from some mobile host's home network. This scheme can eliminate the "tunnel convergence" problem. According to different situations, MMG use multicast distribution tree in its region, or the tunnel to forward multicast packets to mobile host. The performance of each scheme is analyzed and the numerical results show that the new proposal has better performance.

Future mobile data networks will consist of several tiers, which overlap each other. We introduce two of the main technologies, GPRS network and IEEE 802.11 WLAN, which are likely to be widely deployed. We propose schemes to support mobility between these two networks. We also analyze the Mobile IP handoff between hybrid networks and propose our handoff scheme, which reduces handoff delay and packet loss, and prevents the ping-pong effect by utilizing a dwell timer and multi-tunnel technology.

We discuss the Mobile IP handoff and analyze the performance of several existing Mobile IP movement detection algorithms in detail. We then propose our new algorithm, which decreases the handoff delay and improves the handoff performance of a mobile host by actively sending an agent solicitation message after link layer handoff. Computer simulation results prove that our algorithm can effectively improve the performance of TCP/UDP during Mobile IP handoffs.

The key issue at a merging point switch for multipoint-to-point available bit rate (ABR) connections is how to define fairness within a multicast group, and among multicast groups and unicast connections. Another problem lies in the handling of RM cells so that heterogeneous sources can send cells at different data rates while the defined fairness of bandwidth allocation can be achieved. In this paper, we extend the max-min fairness to multipoint-to-point environment and propose a new efficient multipoint-to-point switch algorithm at merging point to solve the problem and allocate bandwidth fairly among multicast sources. The simulation results show that our mechanism provides fair bandwidth allocation and short queue length at switch node, while the convergence time is limited.

A crucial concern in ABR (available bit rate) traffic management for multipoint-to-point connections is how to define fairness within a multicast group, and among multicast groups and unicast connections. Another problem is that AAL5 (ATM adaptation layer 5) does not have any provision within its cell format for the interleaving of cells. In this paper, we extend the max-min fairness to the multipoint-to-point environment and propose a new efficient multipoint-to-point switch algorithm at the merging point to solve the interleaving problem and allocate bandwidth fairly among multicast sources. The simulation results show that our mechanism provides fair bandwidth allocation and short queue length at the switch node, while the convergence time is limited.