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The femto-access-point (FAP), a low power small cellular base station provides better signal quality for the indoor users as to provide high data-rate communications with improved coverage, access network capacity and quality of service. Highly dense femtocellular deployments — the ultimate goal of the femtocellular technology — will require significant degree of self-organization in lieu of manual...
Data availability is critical in distributed storage systems, especially when node failures are prevalent in real life. A key requirement is to minimize the amount of data transferred among nodes when recovering the lost or unavailable data of failed nodes. This paper explores recovery solutions based on regenerating codes, which are shown to provide fault-tolerant storage and minimum recovery bandwidth...
Backoff algorithm is a technique to reduce packet collisions and to improve throughput efficiency in wireless local area network (WLAN). In this research, we propose a new backoff algorithm which is named Binary Exponential Increment Half Decrement (BEIHD) backoff algorithm. Furthermore, we introduce a new discrete Markov chain model for modeling the performance analysis of wireless local area network...
In LTE base-stations, RoHC is a processing-intensive algorithm that may limit the system from serving a large number of users when it is used to compress the VoIP packets of mobile traffic. In this paper, a hardware-software and a full-hardware solution are proposed to accelerate the RoHC compression algorithm in LTE base-stations and enhance the system throughput and capacity. Results for both solutions...
In this paper, the performance of a multichannel cognitive radio network (CRN) where each secondary user (SU) can assemble a constant number of primary channels is investigated. The effects of imperfect spectrum sensing (with false alarms and misdetections) are taken into account and it is assumed that spectrum handover is enabled in the secondary network. A buffering mechanism is introduced to save...
Heterogeneous network with small cells has recently been regarded as a promising scenario in LTE-Advanced systems. In particular, transmission point selection for heterogeneous networks with low-power nodes has drawn attention. We consider in this paper a scenario where a set users is admitted to a macrocell, but it is yet to be determined how each user is served solely or cooperatively by the set...
It is well known that traditional water-filling provides a closed form solution for capacity maximization in orthogonal frequency division multiplex (OFDM) system. In this paper, cooperative power allocation is investigated in a two-transmitter multi-receiver model for OFDM systems. The local full channel state information (CSI) is available at the two transmitters respectively, where each transmitter...
The addressed paper deals with a new analytical formulation called Equivalent Machine Method to evaluate the system throughput of a buffered serial production line. The machines are unreliable and both failure and repair times are assumed to be exponentially distributed. The proposed method is based on the analysis of the different states of each buffer using birth-death Markov processes. Then, each...
The anti-collision mechanism plays a kernel role in random access systems such as RFID, which is usually implemented by MAC protocols such as Dynamic Framed Slotted ALOHA (DFSA). In some standards, there used to define an instruction to cancel the frame in the current interrogation round, such as the QUERYADJUST command in EPCglobal HF Gen 2 [2]. In this paper, we study how to optimally cancel the...
In cognitive radio networks where secondary users (SUs) access spectral white spaces left by primary users (PUs), there exists a trade-off between sensing and transmission. However, the white spaces depend on the PUs' traffic patterns, and this fact can be utilized to optimize SU transmissions after traffic identification. This paper studies the effective approaches to adapt SU transmissions to the...
The conventional hierarchical cooperation (HC) scheme proposed by Ozgur et al. [1] is a novel communication scheme that can achieve linear capacity scaling, O(N) in wireless ad-hoc network from the viewpoint of information theory without considering control and data overhead. In this paper, we investigate the effects of practical parameters such as packet arrival rate, control overhead and data overhead...
Quality of Service (QoS) differentiation measurement provides the ability to evaluate different level of QoS support in 4G networks such as Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). Many research studies around the world have addressed the QoS Differentiation (QoS-Diff) considerations, however, to the best of our knowledge, only a few have attempted to...
The use of directional antennas in support for ad hoc communications has increased significantly since these antennas provide throughput gain and increase space division. Most of the proposed directional MAC protocols in the literature rely on the use of control frames - such as RTS/CTS - for channel reservation and to reduce the collision probability of data frames. However, RTS/CTS control frames...
Frequency reuse schemes are an interference management techniques well suited to OFDMA-based cellular networks. In this paper, analytical expressions are derived for the worst case Signal to Interference Ratio (SIR) ratio for both Fractional Frequency Reuse (FFR), and Soft Frequency Reuse (SFR). Also, analytical expressions are derived for the best inner radius using the worst SIR in both FFR, and...
Cognitive radios have applied various forms of artificial intelligence (AI) to wireless systems in order to solve the complex problems presented by proper link management, network traffic balance, and system efficiency. Case-based reasoning (CBR) has seen attention as a prospective avenue for storing and organizing past information in order to allow the cognitive engine to learn from previous experience...
Exact temporal analyses of multi-rate synchronous dataflow (MRSDF) graphs, such as computing the maximum achievable throughput, or sufficient buffer sizes required to reach a minimum throughput, require a homogeneous representation called a homogeneous synchronous dataflow (HSDF) graph. The size of such an HSDF graph may, in the worst case, be exponential in the size of the MRSDF graph. In this paper,...
In this paper, a throughput enhanced version of a new True Random Bit Generator (TRBG) based on a time-delay sampled-data system is proposed. This new TRBG has both analog and digital parts, which provides the dynamic behavior and the sample and delay process, respectively. The simple system equations and the ease of implementation make this new TRBG very practical. The only required components for...
In this paper, we propose a graph-theoretic algorithm that can be used to analyze complex chemical processes comprising of multiple energy integration loops. Such networks are known to exhibit dynamics in multiple time scales. The algorithm uses information on the order of magnitude of the different energy flows and determines automatically the time scales where the units evolve, the manipulated inputs...
This paper presents an online controller for regulating the throughput of instruction-sequences in multicore processors using dynamic voltage-frequency scaling. The proposed control law comprises an integral controller whose gain is adjusted online based on the derivative of the frequency-throughput relationship. This relationship is modeled as a stochastic DEDS having no analytic functional form,...
Cognitive Network is one of the most prevailing development directions in the future network, prominent in enhancing the utilization of the network resource. Although the research on routing mechanism in Cognitive Network arises more attention in the recent years, the current mechanism provides limited methods for ameliorating the instability performance caused by the mobility of the Cognitive Radio...
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