The current version of IEEE 802.15.4 MAC protocol does not support energy-efficient mobility for the low-power device. In this paper, we propose an energy-efficient sleep mode as part of the IEEE 802.15.4 that can conserve energy by considering mobility of mobile sensor devices. The proposed energy-efficient sleep mode dynamically extends the sleep interval if there is no data to transmit from the device or receive from corresponding nodes.

The CSMA/CA driven MAC protocols withhold packet transmissions from exposed stations when they detect carrier signal above a certain threshold. This is to avoid collisions at other receiving stations. However, this conservative scheme often exposes many stations unnecessarily, and thus minimizes the utilization of the spatial spectral resource. In this paper, we demonstrate that remote estimation of the status at the active receivers is more effective at avoiding collisions in wireless networks than the carrier sensing. We apply a new concept of the interference range, named as n-tolerant interference range, to guarantee reliable communications in the presence of n (n≥ 0) concurrent transmissions from outside the range. We design a distributed interference preventive MAC ( IP-MAC ) using the n-tolerant interference range that enables parallel accesses from the noninterfering stations for an active communication. In IP-MAC, an exposed station goes through an Interference Potentiality Check (IPC) to resolve whether it is potentially interfering or noninterfering to the active communication. During the resolve operation, IPC takes the capture effect at an active receiver into account with interfering signals from a number of possible concurrent transmissions near that receiver. The performance enhancement offered by IP-MAC is studied via simulations in different environments. Results reveal that IP-MAC significantly improves network performance in terms of throughput and delay.

In cognitive radio networks, secondary users exchange control information to utilize the available channels efficiently, to maintain connectivity, to negotiate for data communication such as sender-receiver handshakes, for neighbor discovery etc. This task is not trivial in cognitive radio networks due to the dynamic nature of network environment. Generally, this problem is tackled by using two famous approaches. The first one is the use of common control channel (CCC) and the second one is using channel hopping (a.k.a sequence-based protocols). The use of CCC simplifies the processes of MAC protocols. However, it may not be feasible in cognitive radio networks as the available channels, including control channel, are dynamically changing according to primary user activities. Channel hopping approaches can tolerate the failure of network due to primary user activities. But it causes significant amount of channel access delay which is known as time to rendezvous (TTR). In this paper, we propose a hybrid protocol of these two mechanisms. This hybrid protocol can maintain connectivity and it can guarantee the secondary users to be able to exchange necessary control information in dynamic environment. In our hybrid protocol, we use multiple control channels. If some control channels are unavailable in case of primary user appearances, secondary users still can communicate on different control channels, so it can be more tolerable primary user activities than normal CCC approaches. Channel hopping is performed only for control channels, so it provides relatively small amount of channel access delay.

A dynamic coding mechanism is presented to implement distributed signature based IDS (Intrusion Detection System) in IP-USN (IP-based Ubiquitous Sensor Networks). The proposed scheme allows the creation of a lightweight IDS in terms of storage, messaging and energy consumption, which make it appropriate for resource constrained sensor devices.

In this paper, we propose and evaluate the performance of Wireless ATM MAC layer protocol to support efficiently various ATM traffics, such as CBR, VBR, ABR and UBR, in wireless ATM network environments for reverse and forward link. The proposed MAC protocol could extend efficiently the service discipline of ATM traffics from wired network to wireless ATM network environments. Thus, available bandwidth, which is remained except the bandwidth for CBR and VBR traffics, could be effectively allocated to ABR and UBR traffics. Especially, in view of reverse link, two-phase scheduling algorithm supports successfully variable characteristics of VBR traffic. And, in view of forward link, 'Wireless Dynamic Weighted Earliest Deadline First' scheduling algorithm minimizes the mean cell delay and required buffer size. Simulation results show that proposed method provides effective performance in wireless ATM environments.

To support efficiently the high-speed service and the multimedia service in mobile communication environments, network architecture is generally based on small cell radius structure to increase the wireless channel capacity. In a small cell radius structure based mobile network environment, a mobile station with large mobility should perform frequent handover. Thus, advanced handover mechanism should be provided, and must be done fastly. For these reasons, we suggest the efficient handover mechanism based on forward handover method in this paper. Proposed handover mechanism could support fast handover procedure, and is performed by using optimized path. Also, proposed handover mechanism could support QoS (Quality of Service) attribute of multimedia traffic during handover procedure. We evaluated the performance of proposed handover mechanism, and analysis results show that the suggested forward handover mechanism has less blocking ratio and lower delay than conventional backward handover mechanism.

This paper presents an autonomous traffic engineering framework, named ATE, a highly efficient data dissemination mechanism for multipath data forwarding in Wireless Sensor Networks (WSNs). The proposed ATE has several salient features. First, ATE utilizes three coordinating schemes: an incipient congestion inference scheme, an accurate link quality estimation scheme and a dynamic traffic diversion scheme. It significantly minimizes packet drops due to congestion by dynamically and adaptively controlling the data traffic over congested nodes and/or poorer quality links, and by opportunistically exploiting under-utilized nodes for traffic diversion, while minimizing the estimation and measurement overhead. Second, ATE can provide with high application fidelity of the network even for increasing values of bit error rates and node failures. The proposed link quality estimation and congestion inference schemes are light weight and distributed, improving the energy efficiency of the network. Autonomous Traffic Engineering has been evaluated extensively via NS-2 simulations, and the results have shown that ATE provides a better performance with minimum overhead than those of existing approaches.

Cubic TCP, one of transport protocols designed for high bandwidth-delay product (BDP) networks, has successfully been deployed in the Internet. Multi-homed computers with multiple interfaces to access the Internet via high speed links will become more popular. In this work, we introduce an extended version of Cubic TCP for multiple paths, called MPCubic. The extension process is approached from an analysis model of Cubic by using coordinated congestion control between paths. MPCubic can spread its traffic across paths in load-balancing manner, while preserving fair sharing with regular TCP, Cubic, and MPTCP at common bottlenecks. Moreover, to improve resilience to link failure, we propose a multipath fast recovery algorithm. The algorithm can significantly reduce the recovery time of data rate after restoration of failed links. These techniques can be useful for resilient high-bandwidth applications (for example, tele-health conference) in disaster-affected areas. Our simulation results show that MPCubic can achieve stability, throughput improvement, fairness, load-balancing, and quick data rate recovery from link failure under a variety of network conditions.

Nowadays portable devices with multiple wireless interfaces and using multimedia services are becoming more popular on the Internet. This paper describes a family of multipath binomial congestion control algorithms for audio/video streaming, where a low variant of transmission rate is important. We extend the fluid model of binomial algorithms for single-path transmission to support the concurrent transmission of packets across multiple paths. We focus on the extension of two particular algorithms, SQRT and IIAD, for multiple paths, called MPSQRT and MPIIAD, respectively. Additionally, we apply the design technique (using the multipath fluid model) for multipath TCP (MPTCP) into the extension of SQRT and IIAD, called fbMPSQRT and fbMPIIAD, respectively. Both two approaches ensure that multipath binomial congestion control algorithms achieve load-balancing, throughput improvement, and fairness to single-path binomial algorithms at shared bottlenecks. Through the simulations and comparison with the uncoordinated protocols MPSQRT/MPIIAD, fbMPSQRT/fbMPIIAD and MPTCP, we find that our extended multipath transport protocols can preserve lower latency and transmission rate variance than MPTCP, fairly share with single-path SQRT/IIAD, MPTCP and TCP, and also can achieve throughput improvements and load-balancing equivalent to those of MPTCP under various scenarios and network conditions.

The aggregate throughput of wireless mesh networks (WMNs) can be significantly improved by equipping the mesh routers with multiple radios tuned to orthogonal channels. Not only the links using orthogonal channels can be activated at a time, but some links in the same channel also can be activated concurrently if the Signal-to-Interference-and-Noise Ratio (SINR) at their receivers is not lower than the threshold, which is the spatial-reuse characteristic. STDMA is considered as one of the medium access schemes that can exploit spatial reuse to improve network throughput. Past studies have shown that optimizing the performance of STDMA is NP-Hard. Therefore, we propose a STDMA-based scheduling algorithm that operates in a greedy fashion for WMNs. We show that the proposed algorithm enhances not only the throughput but also the fairness by capturing the essence of spatial-reuse approach of STDMA and giving medium access opportunities to each network element based on its priority. We furthermore validate our algorithm through theoretical analysis and extensive simulations and the results show that our algorithm can outperform state-of-the-art alternatives.

We study joint rate control and resource allocation with a packet collision constraint that maximizes the total utility of secondary users in cognitive radio networks. We formulate and decouple the original optimization problem into separable subproblems and then develop an algorithm that converges to optimal rate control and resource allocation. The proposed algorithm can operate on different time-scales to reduce the amortized time complexity.

In this paper, a hybrid overlay/underlay cognitive radio system is modeled as an M/M/1 queue where the rate of arrival and the service capacity are subject to Poisson alternations. Each packet as a customer arriving at the queue makes a decision to join the queue or not. Upon arrival, the individual decision of each packet is optimized based on his observation about the queue length and the state of system. It is shown that the individually optimal strategy for joining the queue is characterized by a threshold of queue length. Thus, the individual optimal threshold of queue length is analyzed in detail in this work.

In typical end-to-end recovery protocols, an ACK segment is delivered to a source node over a single path. ACK loss requires the source to retransmit the corresponding data packet. However, in underwater wireless sensor networks which prefer flooding-based routing protocols, the source node has redundant chances to receive the ACK segment since multiple copies of the ACK segment can arrive at the source node along multiple paths. Since existing RTO calculation algorithms do not consider inherent features of underlying routing protocols, spurious packet retransmissions are unavoidable. Hence, in this letter, we propose a new ACK loss-aware RTO calculation algorithm, which utilizes statistical ACK arrival times and ACK loss rate, in order to reduce such retransmissions.

Cognitive radio is one of the most promising wireless technologies and has been recognized as a new way to improve the spectral efficiency of wireless networks. In a cognitive radio network, secondary users exchange control information for network coordination such as transmitter-receiver handshakes, for sharing spectrum sensing results, for neighbor discovery, to maintain connectivity, and so on. Spectrum utilization and resource optimizations thus rely on information exchange among secondary users. Normally, secondary users exchange the control information via a predefined channel, called a common control channel (CCC). Most of the medium access control (MAC) protocols for cognitive radio networks were designed by assuming the existence of a CCC, and further assuming that it was available for every secondary user. However, the main drawback of using a static CCC is it is susceptible to primary user activities since the channel can be occupied by primary users at any time. In this paper, we propose a MAC protocol for cognitive radio networks with dynamic control channel assignment, called DYN-MAC. In DYN-MAC, a control channel is dynamically assigned based on spectrum availability. Thus, it can tolerate primary user activities. DYN-MAC also supports collision free network-wide broadcasting and addresses other major problems such as primary/secondary user hidden terminal problems.

The overall performance of multi-hop cognitive radio networks (MHCRNs) can be improved significantly by employing the diversity of orthogonal licensed channels in underlay fashion. However, the mutual interference between secondary links and primary links and the congestion due to the contention among traffic flows traversing the shared link become obstacles to this realizing technique. How to control congestion efficiently in coordination with power and spectrum allocation optimally in order to obtain a high end-to-end throughput is motivating cross-layer designs for MHCRNs. In this paper, by taking into account the problem of joint rate adaption, power control, and spectrum allocation (JRPS), we propose a new cross-layer optimization framework for MHCRNs using orthogonal frequency division multiple access (OFDMA). Specifically, the JRPS formulation is shown to be a mix-integer non-linear programming (MINLP) problem, which is NP-Hard in general. To solve the problem, we first develop a partially distributed algorithm, which is shown to converge to the global optimum within a reasonable time interval. We next propose a suboptimal solution which addresses the shortcomings of the first. Using numerical results, we finally demonstrate the efficiency of the proposed algorithms.

Probabilistic Packet Marking (PPM) is a scheme for IP traceback where each packet is marked randomly with an IP address of one router on the attack path in order for the victim to trace the source of attacks. In previous work, a network coding approach to PPM (PPM+NC) where each packet is marked with a random linear combination of router IP addresses was introduced to reduce number of packets required to infer the attack path. However, the previous work lacks a formal proof for benefit of network coding to PPM and its proposed scheme is restricted. In this paper, we propose a novel method to prove a strong theorem for benefit of network coding to PPM in the general case, which compares different perspectives (interests of collecting) at the collector in PPM+NC scheme. Then we propose Core PPM+NC schemes based on our core network coding approach to PPM. From experiments, we show that our Core PPM+NC schemes actually require less number of packets than previous schemes to infer the attack path. In addition, based on the relationship between Coupon Collector's Problem (CCP) and PPM, we prove that there exists numerous designs that CCP still benefits from network coding.

Broadcasting is an essential function in almost all wireless networks. Because of the dynamic nature of environment, broadcasting in cognitive radio ad hoc networks is a great challenge. Cognitive radio network technology has been well studied for more than a decade as a new way to improve the spectral efficiency of wireless networks and numerous precious works have been proposed. However, very few existing works consider how to broadcast messages in cognitive radio networks that operate in multichannel environments and none of these provides a full broadcast mechanism. Therefore, in this paper, we propose a broadcasting mechanism for multichannel cognitive radio ad hoc networks. Then, we analyze the mechanism regarding the speed of message dissemination, number of transmissions, fraction of the users that receive the broadcast message and so forth.

Routing in wireless ad hoc networks is a challenging issue because it dynamically controls the network topology and determines the network performance. Most of the available protocols are based on single-rate radio networks and they use hop-count as the routing metric. There have been some efforts for multirate radios as well that use transmission-time of a packet as the routing metric. However, neither the hop-count nor the transmission-time may be a sufficient criterion for discovering a high-throughput path in a multirate wireless ad hoc network. Hop-count based routing metrics usually select a low-rate bound path whereas the transmission-time based metrics may select a path with a comparatively large number of hops. The trade-off between transmission time and effective transmission range of a data rate can be another key criterion for finding a high-throughput path in such environments. In this paper, we introduce a novel routing metric based on the efficiency of a data rate that balances the required time and covering distance by a transmission and results in increased throughput. Using the new metric, we propose an on-demand routing protocol for multirate wireless environment, dubbed MR-AODV, to discover high-throughput paths in the network. A key feature of MR-AODV is that it controls the data rate in transmitting both the data and control packets. Rate control during the route discovery phase minimizes the route request (RREQ) avalanche. We use simulations to evaluate the performance of the proposed MR-AODV protocol and results reveal significant improvements in end-to-end throughput and minimization of routing overhead.