Channel assignment

The artificial neural net development has had something of a renaissance in the last decade with an impressive range of application areas. From the viewpoint of telecommunication networks and systems, an increasing number of studies can be observed in recent literature dealing with proposed applications of neural nets in telecommunication environments, such as connection admission control in broadband networks, the control of high-speed interconnection networks, channel allocation in cellular mobile systems, adaptive routing, etc. These proposed applications largely use three main neural net classes: feed-forward nets with backpropagation learning, Hopfield feedback nets, and selforganising neural nets. In this paper, we first give an overview of neural net classes and their main properties, and then present a review of applications in telecommunication systems, where attention is devoted to numerical aspects such as the convergence property and learning speed of the proposed neural nets.

Until recently, research on cellular networks concentrated only in single-hop cellular networks. The demand for high throughput has driven to architectures that use multiple hops in the presence of infrastructure. We propose an architecture for multihop cellular ...

Cognitive radio (CR) is a revolutionary technology in wireless communications that enhances spectrum utilization by allowing opportunistic and dynamic spectrum access. One of the key challenges in this domain is how CR users cooperate to dynamically access the available spectrum opportunities in order to maximize the overall perceived throughput. In this paper, we consider the coordinated spectrum access problem in a multi-user single-transceiver CR network (CRN), where each CR user is equipped with only one half-duplex transceiver. We first formulate the dynamic spectrum access as a rate/power control and channel assignment optimization problem. Our objective is to maximize the sum-rate achieved by all contending CR users over all available spectrum opportunities under interference and hardware constraints. We first show that this problem can be formulated as a mixed integer nonlinear programming (MINLP) problem that is NP-hard, in general. By exploiting the fact that actual communication systems have a finite number of available channels, each with a given maximum transmission power, we transfer this MINLP into a binary linear programming problem (BLP). Due to its integrality nature, this BLP is expected to be NP-hard. However, we show that its constraint matrix satisfies the total unimodularity property, and hence our problem can be optimally solved in polynomial time using linear programming (LP). To execute the optimal assignment in a distributed manner, we then present a distributed CSMA/CA-based random access mechanism for CRNs. We compare the performance of our proposed mechanism with reference CSMA/CA channel access mechanisms designed for CRNs. Simulation results show that our proposed mechanism significantly improves the overall network throughput and preserves fairness.

Abstract A real-time object-oriented expert system is developed for mobile radio networks. The goals, facts, procedural and heuristic rules related to the mobile radio environment are stored in the knowledge base. This knowledge is put together with an inference ...

In recent years, multi-channel multi-radio Wireless Mesh network has become one of the most important technologies in the evolution of next-generation networks. Its multi-hop, self-organization, self-healing and simple deployment is an effective way to solve the bottleneck problem of last mile. In this paper, we propose a new routing metric called WAEED, deployed in JCWAEED protocol, a joint channel assignment and weighted average expected end-to-end delay routing protocol which considers both interference suppression with factor IF and end-to-end delay. Additionally, we give the exact calculation formula of transmission delay and queuing delay. Simulations results demonstrate that JCWAEED outperforms other joint design routing protocols in terms of throughput, end-to-end delay and packet loss rate.

Many spectrum access/sharing algorithms for cognitive radio networks (CRNs) have been designed assuming multiple transceivers per CR user. However, in practice, such an assumption may not hold due to hardware cost. In this paper, we address the problem of assigning channels to CR transmissions, assuming one transceiver per CR. The primary goal of our design is to maximize the number of feasible concurrent CR transmissions with respect to both spectrum assignment and transmission power. Energy conservation is also treated, but as a secondary objective. The problem is posed as a utility maximization problem subject to target rate demand and interference constraints. For multi-transceiver CRNs, this optimization problem is known to be NP-hard. However, under the practical setting of a single transceiver per CR user, we show that this problem can be optimally solved in polynomial time. Specifically, we present a centralized algorithm for the channel assignment problem based on bipartite matching. We then integrate this algorithm into distributed MAC protocols. First, we consider a single-hop CRN, for which we introduce a CSMA-like MAC protocol that uses an access window (AW) for exchanging control information prior to data transmissions. This approach allows us to realize a centralized algorithm in a distributed manner. We then develop a distributed MAC protocol (WFC-MAC) for a multi-hop CRN. WFC-MAC improves the CRN throughput through a novel distributed channel assignment that relies only on information provided by the two communicating users. We compare the performance of our schemes with CSMA/CA variants. The results show that our schemes significantly decrease the blocking rate of CR transmissions, and hence improves the network throughput.

Optical mesh network infrastructures have emerged as the technology of choice for next generation transport networks. At the same time, distributed, IP-based, control architectures have been proposed for intelligent optical networks, as a means to automate operations, enhance interoperability and facilitate the deployment of new applications. While distributed control in general enhances scalability and flexibility, it has also been observed that the requisite topology and link state information summarization may result in sub-optimal path computation, especially for shared mesh restoration paths. This paper presents a distributed control plane for optical mesh networks, focusing on the distributed path computation and provisioning mechanisms. It discusses the tradeoff between path computation efficiency for shared mesh restoration paths and the type of network link state and topology information that is disseminated via distributed routing protocols. We show that with appropriately...

Efficient spectrum-sharing mechanisms are crucial to alleviate the bandwidth limitation in wireless networks. In this paper, we consider the following question: can free spectrum be shared efficiently? We study this problem in the context of 802.11 or WiFi networks. Each access point (AP) in a WiFi network must be assigned a channel for it to service users. There are only

We study the problem of on-line joint QoS routing and channel assignment for performance optimization in multi-channel multi-radio wireless mesh networks, which is a fundamental issue in supporting quality of service for emerging multimedia applications. To our best knowledge, this is the first time that the problem is addressed. Our proposed solution is composed of a routing algorithm that finds

Wireless mesh networks have numerous advantages in terms of connectivity as well as reliability. Traditionally the nodes in wireless mesh networks are equipped with single radio, but the limitations are lower throughput and limited use of the available wireless channel. In order to overcome this, the recent advances in wireless mesh networks are based on multi-channel multi-radio approach. Channel assignment is a technique that selects the best channel for a node or to the entire network just to increase the network capacity. To maximize the throughput and the capacity of the network, multiple channels with multiple radios were introduced in these networks. In the proposed system, algorithms are developed to improve throughput, minimise delay, reduce average energy consumption and increase the residual energy for multi radio multi-channel wireless mesh networks. In literature, the existing channel assignment algorithms fail to consider both interflow and intra flow interferences. The limitations are inaccurate bandwidth estimation, throughput degradation under heavy traffic and unwanted energy consumption during low traffic and increase in delay. In order to improve the performance of the network distributed optimal congestion control and channel assignment algorithm (DOCCA) is proposed. In this algorithm, if congestion is identified, the information is given to previous node. According to the congestion level, the node adjusts itself to minimise congestion.