The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The conventional cooperative protocols have to face some problems in practical broadcast and multicast systems because feedback channel is unavailable. An adaptive cooperative relay protocol, which can be adopted in future broadcast systems, is proposed in this paper. The outage probability performance of this protocol is analyzed over Nakagami-m fading channel, and the asymptotic expression of outage...
In this paper, a novel method for mobile terminal session signal to interference ratio (SIR) prediction is presented. The method is based on clustering and classification algorithms configuring a fully-automatic process, highly adaptable to the deployment scenario. It is focused on the prediction of the session SIR probability density function (pdf) of each user whose knowledge will allow for the...
In this paper, based on the effective capacity theory, we identify the maximal arrival rate of secondary user that an arbitrary ON/OFF primary channel can sustain, in the presence of sensing errors. We find that, the arrival rate of secondary user with statistical QoS requirement, is limited by both the effective capacity provided by primary channel, and the packet collision probability constraint...
In this paper, a joint blind synchronization and demodulation scheme is developed for ultra-wideband (UWB) impulse radio systems. Based on the prior knowledge of the direct-sequence (DS) spread codes, the proposed approach can achieve frame-level synchronization with the help of frame-rate samples. Taking advantage of the periodicity of the DS spread codes, the frame-level synchronization can be carried...
In this paper, the performance of a dual-hop Amplify-and-Forward (AF) multi-antenna relay network, with end-to-end (e2e) best antenna selection, is investigated. To investigate the performance of this system, we first derive the exact outage probability in closed-form. It is then used to obtain expressions for e2e SNR moments and the average symbol/bit error rate (SER/BER) valid for a large class...
In this paper, we investigate the fairness between two secondary user (SU) groups in an opportunistic spectrum access networks (OSA). First, for a given number of allocated channels the throughput of each SU group is analyzed in terms of its forced termination and blocking probabilities using continuous time Markov model. Based on these calculations, the fairness between two SU groups is discussed...
We consider the application of switch-and-stay transmit diversity (SSTD) to a three-node cooperative diversity system with decode-and-forward relaying. The basic idea of SSTD generally is to use a certain transmit antenna as long as the induced signal quality satisfies a given requirement while the transmitter switches to another antenna element if this is no longer the case. Applying this principle...
Applications of location estimation have drawn lots of interests in recent years. Many schemes have been developed to estimate the locations of the concerned users. Conventionally, the location of each user is estimated independently by its own observations from the local environment. In this paper, we propose a cooperative location estimation scheme. From the encounter history of a specific user...
In this paper, we propose an output-threshold multiple relay selection scheme for dual-hop multi-branch cooperative wireless networks. The proposed scheme selects the first Lc arbitrary ordered relays out of L relays such that the maximal ratio combined signal-to-noise-ratio (SNR) of the Lc relayed paths and the direct path barely exceeds a preset threshold. Closed-form expressions are derived for...
Dynamic spectrum allocation schemes enable users to share spectrum resources by exploiting the variations in spectrum demand over time and space. Performing dynamic spectrum allocation centrally can be prohibitively complex. Therefore distributed schemes in which users can access the available channels independently may be preferable to centralized allocation. However, in distributed dynamic spectrum...
High energy consumption at mobile devices is a critical issue for end users to access and enjoy high data-rate multimedia applications and services in Wireless Local Area Networks (WLANs). This paper develops an analytical framework for analyzing and comparing the energy efficiency performance of IEEE 802.11n Medium Access Control (MAC) protocol and a Busy Tone Based Cooperative MAC Protocol(namely...
Collaborative sensing in cognitive radio networks is able to significantly improve the detection probability for the existence of primary user transmission. However, it is usually assumed that there exists orthogonal channels for the cognitive users to send the detection information to the decision center, which is not realistic. In this paper, we consider a practical scenario in which there is a...
In this paper, we have studied the energy efficiency of cooperative networks operating in either the fixed Amplify-and-Forward (AF) or the selective Decode-and-Forward (DF) mode. We consider the optimization of the M-ary quadrature amplitude modulation (MQAM) constellation size to minimize the bit energy consumption under given bit error rate (BER) constraints. In the computation of the energy expenditure,...
This paper aims at answering the questions of how to enable cooperative communications in random access networks. And, since cooperation introduces extra transmissions in the channel, what are the benefits and possible tradeoffs associated with cooperation? To achieve this goal, a novel cooperative protocol for wireless networks based on IEEE 802.11 random access protocol is proposed. The proposed...
The performance of a cooperative network with Cooperative Maximal Ratio Combining (C-MRC) is analyzed. To this end, we propose a heuristic approximation to the total received SNR (signal-to-noise ratio) at the destination. The approximation is not only an accurate representation of the received SNR, but also amenable to performance analysis. We then derive the probability density function (PDF) of...
In this paper, we quantify the expected symbol loss probability in mobile multi-hop relaying systems employing Orthogonal Frequency Division Multiple Access (OFDMA) Techniques. We obtain the expected number of collisions and calculate the probability of symbol loss when a conflict occurs between subcarriers of two or more non-transparent relay stations, as well as we calculate the average symbol loss...
The Disruption Tolerant Networks (DTNs) are vulnerable to insider attacks, in which the legitimate nodes are compromised and the adversary modifies the delivery metrics of the node to launch harmful attacks in the networks. The traditional detection approaches of secure routing protocols can not address such kind of insider attacks in DTNs. In this paper, we propose a mutual correlation detection...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.