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In distributed networks such as wireless ad hoc networks, local and lossy logs are often available on individual nodes. We propose REFILL, which analyzes lossy and unsynchronized logs collected from individual nodes and reconstructs the network behaviors. We design an inference engine based on protocol semantics to abstract states on each node. Further we leverage inherent and implicit event correlations...
The existing key management paradigms cannot deal with these challenges effectively. In this paper, we circumvent these obstacles and propose a novel key management model by close this gap. The new paradigm of traditional broadcast is a hybrid encryption and group key agreement. Such a system, each Member has a single public/secret key pair is created. Members of the public key on the remote to see...
Ad-hoc networks are promising complements for the infrastructure based network under disastrous scenarios. However, due to the heterogeneous surrounding environment of each user, the channel availability of each user may be quite different. Cognitive radio emerges as a promising technology to enable two users to communicate under different channel availability, by opportunistically accessing available...
We study wireless ad hoc networks in the absence of any channel contention or transmit power control and ask how antenna directivity affects network connectivity in the interference limited regime. We answer this question by deriving closed-form expressions for the outage probability, capacity and mean node degree of the network using tools from stochastic geometry. These novel results provide valuable...
As professional mobile radio (PMR) networks evolve to a new generation based on Long Term Evolution (LTE), a new direct communication mode needs to be developed. Not only in PMR networks, but the increase of proximity services due to the explosion of the internet of things bring us to a new communication paradigm. The PMR users have very specific requirements and one of those is the ability to communicate...
Rendezvous in cognitive radio ad-hoc networks (CRAHNs) is a key step for a pair of unknown cognitive radio (CR) users to initiate communication. Channel hopping (CH) provides an effective method to guarantee rendezvous in CRAHNs. To design a CH scheme, assumption of symmetric channel information is widely used in the literature. This assumption may ease the CH design, but unable to capture the dynamic...
Delay Tolerant Networks (DTNs) are sparse mobile ad-hoc networks in which there is typically no complete path between the source and destination. Multicast is an important group communication paradigm that is required by many potential DTN applications, such as data dissemination during military and rescue operations. While multicasting has been studied extensively in the context of the Internet and...
In this paper, we address the trade-off between radiated power and achieved throughput in wireless multiple-input and multiple-output (MIMO) systems that evolve over time in an unpredictable fashion (e.g. due to changes in the wireless medium or the users' QoS requirements). Contrary to the static/stationary channel regime, there is no optimal power allocation profile to converge to (either static...
This paper addresses the benefits of introducing exclusion regions around both transmitters and receivers in D2D wireless networks. Such exclusion regions offer protection from interference at the expense of a sparser spatial reuse of spectrum, bringing about a tradeoff whose resolution entails optimizing the size of the exclusion regions as function of relevant system parameters. Our figure of merit...
Wireless networks are fundamentally limited by the intensity of the received signals and by their inherent interference. It is shown here that in finite ad hoc networks where node placement is modelled according to a Poisson point process and no carrier sensing is employed for medium access, the SINR received by nodes located at the border of the network deployment/operation region is on average greater...
Exploiting multi-user diversity (MUD) for multicast consists in choosing the data rate(s) utilized to serve a number of users who have different channel qualities. Some of the proposed multicast schemes aim to maximize the throughput (e.g. EMTH), while others seek to reduce the transmission time (e.g. EMTT). Actually, it is well known that the process of computing the accurate MUD multicast throughput...
Collisions due to interference at MAC layer limit the throughput of Ad Hoc networks using IEEE 802.11 protocol at medium and high load conditions. The proposed MAC layer MAC-CPI-A (Collision Prevention due to Interference) protocol prevents collisions due to interference completely. In the proposed protocol every node refrains from beginning its transmission if any node within its ‘maximum interference...
Recently, research efforts to enable and improve RF-powered computers with backscattering have been conducted. In backscatter networks with monostatic readers, however, performance degradation can be occurred due to self-interference. To this end, in this paper, we suggest a reader system for RF-powered computers which separates the transmitter and the receiver, compare the system with previous proposals...
This paper proposes a pairwise SIR-based random sequential scheduling algorithm for wireless D2D communications. We derive an upper and a lower bound on the number of scheduled links by identifying the equivalence between the proposed algorithm and the Random Sequential Adsorption (RSA) process in physics. We then study the optimal SIR threshold, which is a key parameter in the proposed algorithm,...
Wireless communication at millimeter wave (mmWave) frequencies is attractive for cellular, local area, and ad hoc networks due to the potential for channels with large bandwidths. As a byproduct of directional beamforming and propagation differences, some studies have claimed that mmWave networks will be noise rather than interference limited. This paper presents a derivation of the instantaneous...
Directional communication in Mobile Ad-hoc Networks (MANETs) helps in mitigating the problems of exposed nodes and interference, while providing better spatial reuse. However, use of directional antenna also leads to the problem of deafness. This paper presents a novel method to mitigate deafness in MANETs. In the proposed method, Request To Send (RTS), Clear To Send (CTS), Data and Acknowledgement...
This paper addresses the concern of deafness in directional antennas for wireless ad-hoc networks. Deafness is caused when a node X continually attempts to communicate with node Y but is ineffective, because Y is currently tuned to some other antenna beam. In this paper, we first outline diverse factors which give to such deafness in directional antennas and its considerable impact on network performance...
Escalation in mobile devices has powered the demand for wireless networks. With the ripening of industry standards and the deployment of wireless networking across a broad commercial section, wireless technology has expanded over the age. Wireless ad-hoc network technologies and standards such as IEEE 802.11s (WANET) are efficient, economic, simple to send, permit the brisk setup of a remote system...
Cognitive radio (CR) technology is regarded as a promising solution by enabling unlicensed users to exploit the licensed spectrum unused by the licensed user in an opportunistic manner. Since in a mobile CR network, if unlicensed users move away from each other, their relative distance changes. Thus, the unlicensed user transmission power needs to be adapted to maintain their communications. In the...
The long propagation delay of underwater acoustic communications has made traditional handshaking-based medium access control (MAC) protocols inefficient for underwater sensor networks (UWSNs). We envision that this unique feature, although often taken as negative, can be leveraged to improve the parallelism between multiple senders, i.e., transmitting data simultaneously so as to achieve higher channel...
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