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In this paper, we investigate the aggregate throughput and proportional fairness of two independent secondary user (SU) groups in a cognitive radio (CR) network. Using a continuous time Markov chain, the expression for the aggregate throughput as a function of traffic intensity, forced termination and blocking probabilities is derived. Furthermore, throughput loss of the individual SU groups is analyzed...
In this paper we present new modeling and analysis a threshold-based mechanism for characterizing the TCP congestion avoidance during multiple connections. We develop two models which are source centric model and network centric model that relative to the threshold respectively. We obtain the closed form solution for TCP throughput via simple analysis and present the pseudo-code for the threshold...
This paper proposes an evolutionary approach to the network traffic optimization under the constraint of congestion avoidance. The individuals of the evolving population directly represents a set of paths in a network, and corresponding crossover and mutation operators are provided. The optimization is a global one, i.e. it will not optimize the paths independently but also taking link sharing into...
This paper proposes a cooperative multiple access protocol based on the distributed coordination function (DCF) request-to-send/clear-to-send (RTS/CTS) scheme for distributed wireless networks. It answers three key questions concerning cooperation from the network perspective, namely when to cooperate, whom to cooperate with and how to protect cooperative transmissions. According to our protocol,...
Due to the ignorance of the relation between different collisions, traditional medium access control protocols cant achieve their anticipated collision resolution results. This paper proposes a novel way to distribute MAC accesses in MANETs based on collision classification approach and modified backoff schemes. The idea is to avoid cross collisions through dynamically allocated elementary windows...
Since low-density parity-check codes have near-capacity decoding performance and very high decoding throughput, they have been employed as FEC coding scheme in many transmission standards for wireless communication, such as IEEE 802.22n, IEEE 802.16e, DVB-S2, and DTMB. This trend triggers the need for so-called multi-standard LDPC decoders. In this paper, a flexible architecture that supports multiple...
The throughput of a linear cellular uplink with a random number of users, different power control schemes, and cooperative base stations is considered in the large system limit where the number of cells is large for non fading Gaussian channels. The analysis is facilitated by establishing an analogy between the cellular channel per-cell throughput with joint multi-cell processing (MCP), and the rate...
This paper argues that the speed-accuracy trade-off arises as a consequence of Shannon's fundamental theorem for a channel with noise, when coupled with two additional postulates: that people are imperfect information processors, and that motivation is a necessary condition of the speed-accuracy tradeoff.
Channel allocation is an important area of research in open spectrum networks which asserts a significant impact on the spectrum utilization and the fairness among users. This paper studies the optimization of channel allocation, considering multiple objectives. For each objective, a binary programming model is described. Then a new optimization objective called fairness constrained maximum throughput...
Uplink users in cellular networks, such as UMTS/HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage and increasing data rates. This paper focuses on the role of packet scheduling in cellular networks with relay nodes. In particular, two uplink scheduling schemes deploying...
This paper studies the selection of CDMs (CDM, Collecting and Distributing Mode). A connotation for CDSCP (CDSCP, Collecting and Distributing System of Container Port) is presented. After establishing a layered architecture, an optimized model with the goal of the minimum of the network cost is set up. And finally, a heuristic algorithm is advanced.
We propose a hybrid active queue management (AQM) scheme, Proportional Rate-based Control (PRC), which aims to maintain the queue length around the target level by 1) dropping the packet whose arrival rate exceeding maximum desired rate; 2) using virtual queue to control the packet whose arrival rate above minimum desired rate. We compare the performance of PRC through simulation with several well-known...
String matching is one of hot spots in computer science. Many algorithms for string matching have been proposed, but designing an efficient and practical string matching architecture to satisfy high-speed data streaming is difficult and needs further study. In this paper we propose a high throughput configurable string matching architecture based on Aho-Corasick algorithm. The architecture can be...
Constrained by the interior properties of underwater acoustic channels such as limited bandwidth, time-varying multipath propagation, and large propagation delay, the design of multiple access (MAC) protocols for underwater acoustic sensor networks (UWSN) poses significant challenges. Existing MAC protocols for UWSNs exhibit very low performance in channel utilization, throughput and end-to-end delay,...
Unlike traditional wireless routing protocols which use a single fixed path, opportunistic routing explicitly takes advantage of the broadcast nature of wireless communications by using a set of forwarders to opportunistically perform packet forwarding. A key issue in the design of opportunistic routing protocols is the forwarder list selection problem. In this paper we establish a general theory...
A kind of performance evaluation for communication network is presented. In our work, a distributed evaluation system via High Level Architecture (HLA) and a novel quantitative evaluation method are proposed to evaluate communication network on-line. During the weight determination process, a combinative method based on the principle of maximum deviation and subjective estimation is proposed to overcome...
In many areas such as e-commerce, mission-critical N-tier applications have grown increasingly complex. They are characterized by non-stationary workloads (e.g., peak load several times the sustained load) and complex dependencies among the component servers. We have studied N-tier applications through a large number of experiments using the RUBiS and RUBBoS benchmarks. We apply statistical methods...
As the world becomes increasingly dependent on dynamic and up-to-the-moment information, we recognize that broadband networks must be able to convey this information timely and wirelessly, to and from users in motion. Varieties of 802.11 compliant equipment and other types of broadband wireless equipment have been proposed for, and in some areas, being used to meet this need. There have been questions...
In this paper, we highlight the impact of variable Push-To-Talk (PTT) delays on performance of a heterogeneous Land Mobile Radio (LMR) network. We first present the PTT delay values and distributions observed for some commonly used LMR nodes. An analytical model is then developed to estimate the asymmetric throughput problem. The results obtained using this model and simulations show that a LMR node...
UWB is a short range (up to 10 m) wireless communication technology which provides high throughput with low transmission and high reliability. We developed a PHY prototype conformed to ECMA-368, one of UWB standards, and a network simulator for evaluating MAC throughput of ECMA-368. In this paper, we propose an evaluation method considering the characteristic of PHY, the channel model and the propagation...
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