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Hierarchical Mobile IPv6 (HMIPv6) has been proposed to accommodate frequent mobility of an MN and reduce the signaling load in the Internet. In this paper, we propose hierarchical management scheme for Mobile IPv6 where MAP (Mobility Anchor Point) has priority queues for faster processing location update procedure in HMIPv6 system. The performance analysis and the numerical results presented in this paper show that our proposal has superior performance to the hierarchical Mobile IPv6.

In Mobile IPv6, a handover latency is an important issue. To reduce the handover latency, mipshop working group in IETF has studied the fast handovers for Mobile IPv6 (FMIPv6) which creates and verifies a new care-of address (NCoA) in advance before a layer 2 handover resulting in reduced handover latency. Then the paper which reduces delay of a binding update to a home agent (HA) is emerged, called the TEBU (Tentative and Early Binding Update) scheme. This scheme can reduce handover latency, since the NCoA is registered to the HA during the layer 2 handover of FMIPv6. Additionally, if Return Routability (RR) procedure which introduces long delay is performed in advance like the TEBU scheme, the handover latency may be reduced significantly. Therefore, we propose an enhanced TEBU (eTEBU) scheme that the binding update (BU) and RR procedure are started during the layer 2 handover. The BU message and the messages for RR procedure are transferred through a fast binding update message (FBU) of FMIPv6. We perform analysis of handover latency for the performance evaluation. As a result, we found that the eTEBU scheme guarantees lower handover latency than the TEBU scheme and FMIPv6.

The wireless networking is embedded into a wide variety of common devices. In many embedded networking situations, there have been increasing demands on the embedded wireless system for video streaming. However, it is inherently vulnerable to loss from dynamic wireless channel. In order to alleviate the effect of losses in the transport layer, the error control schemes are used. However, since each error control scheme shows different performance, a suitable scheme should be selected and applied. In this paper, we propose and implement a network-adaptive selection of transport error control (NASTE). To verify the feasibility of the proposed NASTE, we have implemented it in the embedded system which includes IEEE 802.11g WLAN environment. The experimental results indicate that the proposed mechanism can enhance the overall transport performance by recovering packet losses.

In this paper, we propose an energy-efficient and traffic-aware CSMA/CA algorithm, referred to as ETCA, that aims to reduce redundant transmission of IEEE 802.15.4 Standard for Low-Rate Wireless Personal Area Networks (LR-WPAN). In Wireless Sensor Networks (WSNs), reducing energy consumption is one of the most important issues because it makes the network life-time longer. Sensor nodes consume most of energy for computing and transmitting operations [1]. Unlike IEEE 802.11, IEEE 802.15.4 MAC doesn’t use Request To Send (RTS) and Clear To Send (CTS) frames, and it still has hidden terminal problems. Thus, if there are some hidden nodes, there are many collisions and retransmissions [2]. To reduce retransmission, we improve the carrier sensing features in MAC layer of IEEE 802.15.4. When the network is busy, the MAC detects it and adaptively chooses parameters of CSMA/CA mechanism to minimize collisions and the number of retransmission based on ETCA. We evaluated the proposed scheme with original 802.15.4 MAC on the ns-2 simulator. The results showed that our scheme outperforms the original by 15% in average when there is a retransmission activity.

In a ubiquitous environment, various sensors and wireless devices communicate with each other. Recently, the number of wireless devices using Bluetooth technology operating in the unlicensed 2.4GHz ISM band is increasing rapidly. Interference among communicating devices sharing the ISM band can cause significant throughput degradation. In this paper, we present an analytical model of packet interference with multi-path fading channel in a cluster of piconets. Through analysis, we obtain the packet collision probability and aggregated throughput assuming capture effect. Numerical examples are given to demonstrate the effect of various parameters such as capture ratio, Rice factor and cluster size on the system performance.

For the extreme short duration of the baseband Impulse Radio (IR) Ultra-Wideband (UWB) transmission waveforms, even small amounts of timing jitter can bring out considerable system performance degradation. Thus jitter performance evaluation and corresponding suppression methods are very important for UWB high rate transceiver. We analyzed the jitter distribution function in UWB systems, also a jitter suppression method is proposed by modification of template waveforms. Performance of our proposed waveforms and traditional template waveforms are compared by analysis and simulation, and the results verify our jitter suppression method works.

The interactive digital multimedia broadcasting stands for a convergence application between digital multimedia broadcasting service and wireless internet service. It develops MPEG-4 BIFS (Binary Format for Scene) technologies which is standard component of associated data service for DMB. In this paper, we propose system architecture of the interactive DMB, called the interaction manager. The interactive DMB facilitates to transmit interactive contents and user can easily use these contents by clicking or typing some additional information. The proposed interactive DMB system can capture and response user interaction information by using the return channel. In this paper, we are mainly focused on extracting the event data of the user interaction on the device. We suggest an analyzer to catch the user event and transform into a specific format for bidirectional DMB service system.