A conflict-insensitive NATed roaming framework using NAToD for proxy mobile IPv4 in WLANs

Providing efficient mobility management in the current Internet is increasingly important due to the quick growth of wireless mobile users. The emerging Proxy Mobile IPv4 (PMIPv4) technique brings a possible solution for that purpose. Since NAT function is widely adopted in IPv4 environment nowadays because of lacking IPv4 addresses, the PMIPv4 interoperating with NAT must be considered. Unfortunately, owing to the possible conflict of private IP address, we encounter a problem in broadcasted point-to-multipoint wireless networks such as IEEE 802.11 networks. To address this issue, we proposed a novel Network Address Translation on Demand (NAToD) scheme, which can well interoperate with the PMIPv4 solution. With our scheme, single public IPv4 addresses can be shared by multiple mobile nodes in both home and foreign networks, low-latency handoff can be achieved, deployment cost can be reduced, and software upgrade can be avoided for mobile nodes in wireless LANs. Our work allows mobile users in WLAN to access Internet based on the advantages of both PMIPv4 and NAT.     

Vegas plus: improving the service fairness

TCP Vegas is a congestion avoidance scheme designed to prevent the periodic packet loss which occurs in traditional schemes. Since Vegas successfully avoids such packet loss, it achieves much higher throughput than TCP Reno. However, it does not concern the fairness among source-destination pairs with different round-trip times (RTTs). We propose a different mechanism to adjust the window size, this allows TCP to provide much better fairness regardless the large variation of RTTs     

A FIFO-based buffer management approach for the ATM GFR services

We investigate the TCP packet transmission over the ATM Guaranteed Frame Rate (GFR) service using a selective packet-discard with buffer vacancy tracking strategy and a packet-based push-out buffering scheme. Our approach is based on FIFO queueing discipline, it features fair sharing of available resources as well as feasibility in hardware implementation     

Challenge and solutions of NAT traversal for ubiquitous and pervasive applications on the Internet

Network Address Translator (NAT) has brought up many changes and opportunities to the Internet. How do the ubiquitous and pervasive applications coexist with NAT and interoperate with each other? In this article, we discuss the essence of NAT sensitive applications as well as the challenge and response for various NAT traversal solutions. All questions pointed to redesign a new NAT framework with a major change to accommodate NAT problems all at once. We introduce a novel next generation NAT (NATng) framework, which consists of a Bi-directional NAT (BNAT) and a Domain Name System Application Level Gateway (DNS_ALG) with a Border Network Address Translator Control Protocol (BNATCP) function to control all BNATs. The above components coordinate and provide bidirectional access capability between intranet and Internet, so all private hosts can be addressed via Fully Qualified Domain Name (FQDN). Logistically, NATng extends the IPv4 address space from or even more. It features high potential to solve the problems for ubiquitous and pervasive applications which may encounter IPv4 address exhaustion on the current Internet.     

An agent-based metric for quality of services over wireless networks

In a wireless LAN environment, clients tend to associate with the nearest access point (AP) which usually provides the strongest signal. However, this does not guarantee that users will receive the best quality of service (QoS) if the population sharing the network capacity were not considered. In other words, within the same access point, the more the population is, the less bandwidth each user will share, and the worse the quality of service will be. In this paper, we proposed an anticipative agent assistance (AAA) which is an agent-based metric for evaluating and managing the resource information of the wireless access points, computing the potential AP list, and providing clients with resource information of APs. We also propose a novel QoS feedback mechanism which allows users to promptly adjust the service quality with AAA according to the throughput and delay requirements. We evaluate the performance of our proposed method using the ns-2 simulator. Numerical results show that AAA achieves: (1) reduce the transmission delay, (2) increase the throughput, (3) improve the network utilization, (4) accommodate more users to access the networks, and (5) achieve load-balancing. Our metric is implementation feasible in various IEEE WLAN environments.     

Performance enhancement of IP forwarding by reducing routing tableconstruction time

In previous work, Lampson et al. (1999) proposed an IP lookup algorithm which performs binary searches on prefixes (BSP). The algorithm is attractive for IPv6 because of its bounded worst-case memory requirement. Although for the sake of fast forwarding, the cost paid for the slowing down insertion is reasonable, the performance of routing-table reconstruction in BGP is too time-consuming to handle the frequent route updates. In this letter, we propose a fast forwarding-table construction algorithm which can handle more than 3600 route updates per second. Moreover, it is simple enough to fulfill the need of fast packet forwarding     

A cross-layer approach for real-time multimedia streaming on wireless peer-to-peer ad hoc network

Peer-to-peer (P2P) live streaming over mobile ad hoc network (MANET) is a state-of-the-art technique for wireless multimedia applications, such as entertainments and disaster recovery. The peers share the live streaming over MANET via multi-hop wireless link, so an efficient data delivery scheme must be required. However, the high churn rate and the frequent mobility baffle the P2P membership management and overlay maintenance. The unreliable wireless connection of MANET leads to the difficulties of large-scale and real-time streaming distribution, and a lack of overlay proximity leads to the inefficient streaming delivery. We present a cross-layer design for P2P over MANET to manage and maintain the overlay, and select efficient routing path to multicast media streams. Our proposed scheme (COME-P2P) integrates both P2P DHT-based lookup and IPv6 routing header to improve the delivery efficiency. Through the cross-layer design, the low layer detects mobility for informing high layer to refine the finger table, and high layer maintains the efficient multicast path for informing low layer to refine the routing table. How to keep stable routing paths for live streaming via IPv6 routing is the main contribution of this paper. The overlay proximity can shorten routing propagation delay, and the hop-by-hop routing can avoid the traffic bottleneck. Through the mathematical analysis and simulation results, COME-P2P can be demonstrated to achieve high smoothness and reduce signaling overhead for live streaming.     

A cross-layer error correction scheme based on multiple-CRC in OFDM/OFDMA wireless networks

The orthogonal frequency division multiplexing access (OFDM/OFDMA) based wireless transmission technology has been widely deployed in recent years. The frame check sequence (FCS) scheme is employed to enhance the reliability of OFDM/OFDMA systems. Since the padding overhead cannot be effectively avoided in OFDM/OFDMA when medium access control frames are encapsulated, we propose a novel cyclic redundancy check based error correction scheme by utilizing the padding space to carry extra segmented FCS information as much as possible; compared with the legacy FCS scheme, our approach greatly enhance the error detection and correction upon the first retransmission (second transmission). A significant performance improvement based on the simulation results is also demonstrated.     

An enhanced congestion avoidance mechanism for TCP Vegas

TCP Vegas detects network congestion in the early stage and successfully prevents periodic packet loss that usually occurs in traditional schemes. It has been demonstrated that TCP Vegas achieves much higher throughput than TCP Reno. However, TCP Vegas cannot prevent unnecessary throughput degradation when congestion occurs in the backward path. In this letter, we propose an enhanced congestion avoidance mechanism for TCP Vegas. By distinguishing whether congestion occurs in the forward path or not, it significantly improves the connection throughput when the backward path is congested.     

A fast IP routing lookup scheme

A major issue in router design for the next generation Internet is the fast IP address lookup mechanism. The existing scheme by Huang et al. (see Proc. IEEE INFOCOM'99, New York, NY, 1999) performs the IP address lookup in hardware in which the forwarding table can be compressed to fit into a reasonable-size SRAM, and a lookup can be accomplished in three memory accesses. We claim that with a little extra memory, it is able to further reduce the lookup time to two memory accesses