Call Blocking Probabilities under a Probabilistic Bandwidth Reservation Policy in Mobile Hotspots

In this paper we study a mobility-aware call admission control algorithm in a mobile hotspot. To this end, a vehicle is considered which has an access point with a fixed capacity. The vehicle alternates between stop and moving phases. When the vehicle is in the stop phase, it services new and handover calls by prioritizing them via a probabilistic bandwidth reservation (BR) policy. Based on this policy, new handover calls may enter the reservation space with a predefined probability. When the vehicle is in the moving phase, it services new calls only. In that phase, two different policies are considered: (a) the classical complete sharing (CS) policy, where new calls are accepted in the system whenever there exists available bandwidth, and (b) the probabilistic BR policy. Depending on the selected policy in the moving phase, we propose the probabilistic BR loss model (if the CS policy is selected) and the generalized probabilistic BR loss model (if the probabilistic BR policy is selected). In both stop and moving phases, where the call arrival process is Poisson, calls require a single bandwidth unit in order to be accepted in the system, while the service time is exponentially distributed. To analytically determine call blocking probabilities and the system’s utilization, we propose efficient iterative algorithms based on two-dimensional Markov chains. The accuracy of the proposed algorithms is verified via simulation.

Multiservice Loss Models in Single or Multi-Cluster C-RAN Supporting Quasi-Random Traffic

In this paper, a cloud radio access network (C-RAN) is considered where the baseband units form a pool of computational resource units and are separated from the remote radio heads (RRHs). Based on their radio capacity, the RRHs may form one or many clusters: a single cluster when all RRHs have the same capacity and multi-clusters where RRHs of the same radio capacity are grouped in the same cluster. Each RRH services the so-called multiservice traffic, i.e., calls from many service classes with various radio and computational resource requirements. Calls arrive in the RRHs according to a quasi-random process. This means that new calls are generated by a finite number of mobile users. Arriving calls require simultaneously computational and radio resource units in order to be accepted in the system, i.e., in the serving RRH. If their requirements are met, then these calls are served in the (serving) RRH for a service time which is generally distributed. Otherwise, call blocking occurs. We start with the single-cluster C-RAN and model it as a multiservice loss system, prove that the model has a product form solution, and determine time congestion probabilities via a convolution algorithm whose accuracy is validated with the aid of simulation. Furthermore, the previous model is generalized to include the more complex case of more than one clusters.

Caching-Aware Intelligent Handover Strategy for LEO Satellite Networks

Recently, many Low Earth Orbit (LEO) satellite networks are being implemented to provide seamless communication services for global users. Since the high mobility of LEO satellites, handover strategy has become one of the most important topics for LEO satellite systems. However, the limited on-board caching resource of satellites make it difficult to guarantee the handover performance. In this paper, we propose a multiple attributes decision handover strategy jointly considering three factors, which are caching capacity, remaining service time and the remaining idle channels of the satellites. Furthermore, a caching-aware intelligent handover strategy is given based on the deep reinforcement learning (DRL) to maximize the long-term benefits of the system. Compared with the traditional strategies, the proposed strategy reduces the handover failure rate by up to nearly 81% when the system caching occupancy reaches 90%, and it has a lower call blocking rate in high user arrival scenarios. Simulation results show that this strategy can effectively mitigate handover failure rate due to caching resource occupation, as well as flexibly allocate channel resources to reduce call blocking.

Probabilistic Retry and Threshold Multirate Loss Models for Impatient Calls

In this paper, a link of fixed capacity is considered that services calls from different service-classes. Calls arrive in the link according to a Poisson process, have an initial (peak) bandwidth requirement while their service time is exponentially distributed. We model this system as a multirate loss system and analyze two different multirate loss models. In the first model, named probabilistic retry loss model, if there is no available link bandwidth, a new call is blocked but retries with a lower bandwidth requirement and increased service time. To allow for the fact that a blocked call may be impatient, we assume that it retries with a probability. In the second model, named probabilistic threshold loss model, a call may reduce its bandwidth requirement (before blocking occurs) based on the occupied link bandwidth. To determine call blocking probabilities in both multirate loss models, we show that approximate but recursive formulas do exist that provide quite satisfactory results compared to simulation.

Handoff Control in Satellite Communication Applying Multi Billboard Manager Method

LEO satellites play an important role in global communication system. LEO satellites have some advantages over GEO and MEO satellites, in respect of power requirement, end-to-end delay & more efficient frequency spectrum. But the main problem of LEO satellite, is that they have large relative speed than the speed of mobile nodes (MN) and earth, so that the handover occurrence is more. As a result, the call blocking probability (Pb ) and force call termination probability (Pf ) is higher. To overcome this problem, Billboard manager based handover (BMBHO) was introduced to reduce the scanning time significantly and also to reduce the Pf . But the main problem of single billboard manager (BM) is that, since all handover requests have to be processed from a single point. In this paper, we have proposed the concept of multi-billboard manager based handover (MBMHO) method to resolve this problem. Thus, handover request will be served more efficiently so that both Pb and Pf are minimized than the BMBHO method.

Hybrid Design and RF Planning for 4G networks using Cell Prioritization Scheme

This article includes hands-on recreation practice on arranging of RF connect with the assistance of Atoll arranging programming device. The primary goal of this task is to structure and plan a RF coordinate with obstruction free correspondence, Optimum inclusion, no forgot about zone in the arranged inclusion guide and extension and reuse of site recurrence &network structure. Using the accessible restricted data transfer capacity vitally in order to take into account millions out of an immense zone with great quality, inclusion, and without obstruction utilizing ATOLL arranging device. Insightful re-utilization of site area later on organize structure will set aside cash for the administrator. Handover component is critical in cell arrange in light of the cell engineering utilized to expand range usage. One approach to improve the phone organize execution is to utilize productive handover prioritization plans, which have a typical trademark lessening the call dropping likelihood to the detriment of expanded call blocking likelihood. Effective prioritization conspire obliges various new calls while ensures the nature of administration (QOS) of Hand over call. This thought depends on the neighboring cells have a covering (the territory served by more than one cell) inclusion zone. Moreover cell cover and burden adjusting plan is proposed to improve the GSM cell limit utilizing a Software advancement pack (SDK). Limit improvement is accomplished by adjusting the heap in neighboring cell prioritization plans when client is exchanging between the cells.

Model for Performance Improvement of Blocking Probability in GMPLS Networks

Generalized multiprotocol Label Switching (GMPLS) is a set of rules which is used in various layers like the Wavelength Division Multiplexing (WDM) layer, Time Division Multiplexing (TDM) layer, etc. to generalize the concepts of labels of Multiprotocol Label Switching networks. A block in call occurs when number of requests is more than the servers and waiting rooms. This call blocking is the very important parameter and can be calculated in terms of probability. There are a number of models to calculate the call blocking probability like Erlang B, Erlang C, etc. This paper suggests a novel, efficient and less – complex model which minimize the call blocking to very much extent for GMPLS networks. This model deals with the factors like number of wavelengths, number of links, traffic intensity, etc. which can help in reducing the call blocking probability and give better results. In this paper, the call-blocking probability is also compared with number of links by considering different wavelengths. A comparison of call-blocking probability of proposed model is also analysed. This paper deals with blocking probability optimization in GMPLS Networks using Fredericks approach. We have used peakedness factor from Fredericks approach in Engset’s formula for this optimization.”