Admission Control

In this paper we propose a new uni ed approach to address simultaneously the issues of trac policing (using leaky buckets), admission control and network dimensioning. First we compute the eective bandwidth of the output of the leaky bucket (both buered and un- buered). We nd a surprising result that eective bandwidth of the output of a buered leaky bucket is independent of the token pool size. Furthermore, the output eective bandwidth ex- hibits discontinuous behavior as the token pool size approaches in nity. We use these results in an optimization model to nd the \optimal" leaky bucket parameters. We explain how this optimization program can be used to do network dimensioning if the input trac characteristics are known, or to do connection admission control if the network parameters are xed.

In [18], Wu and Bertsekas considered the problem of optimal admission control in a single-hop wireless infra- structure mode to determine whether or not to accept a new session request, given a particular configuration of users of various classes in various regions. The authors assumed the existence of an algorithm that can deter- mine, for any distribution of users of various classes in various regions, whether there is a feasible power assign- ment satisfying the signal-to-noise requirements for all users and, if so, provide a unique power assignment for the distribution. They formulated the problem as a Markov decision process to provide a technique that is enough to be applicable and can be implemented in real time in a distributed manner between the cells. One of the advantages of such technique is that it can incorporate an arbitrary amount of detail necessary to describe real wireless infrastructure systems. However, this work is based on a set of assumptions (like the existence of algorithm which assigns dynamically the resources to users, the probability of moving is known a priori , etc.) that may restrict the model in the implementation phase.

Abstract. The family of IEEE 802.11 protocols has become the most popular wireless access method. In recent years, other technologies have started to complement 802.11 networks, for example, for Internet access in rural networks. Specifically, point-to-point links based on WiMAX and on TV White Space Dynamic Spectrum Access technologies are used to connect a wired Internet access with a set of 802.11 end users. These heterogeneous and multi-hop networks face many challenges in order to provide QoS guarantees. One of these challenges is the design of admission control algorithms. In this paper we develop a blackbox approach for designing admission control algorithms suitable for these kind of networks. The methodology is based on a combination of active measurements and statistical learning tools. The results obtained during simulation and testing in a laboratory testbed show that show that the methodology achieves good accuracy.

In [13], a Connection Admission Control and RBs reservation scheme is proposed to reduce call dropping probability. The scheme employs RB reservation algorithm to allocate the maximum number of RBs to all calls when possible. And if the cell is over-loaded, some of the calls in the cell might receive RBs lower than the requested RBs .It degrades NC with largest allocated resources allocated resources and lower priority (NRT) calls to minimum RB required to admit HC when resources are insufficient. Similarly, the scheme admits NC which has not exceeds its latency by degrading NRT calls. The scheme rejects both HC and NC if resources obtained from degradation are insufficient. The scheme reduces handoff dropping probability, maintains low new call blocking probabilities and ensures efficient resource utilization. However, the scheme unfair due to NRT call degradation.

The rest of the paper is organized as follows: Section II introduces the self-similarity theoretical basis, the M/Pareto model describing the burst traffic of many ON/OFF sources and the FBM model for self-similar traffic prediction; Section III presents a model for calculating the effective bandwidth of WiMAX network traffics; Section IV presents the modified self-similar admission control algorithm; Section V explores the simulation results and the analysis; Section VI concludes the work presented in this paper and highlights the recommenda- tion for the future work.

resources, increase the complexity of performance requirements. A recent work reported MLF[1] a practical (secured-concurrent-available) end-to-end framework based on admission control policies achieves robust performance on a wide range of Internet services subject to huge variation in load. In this paper a differentiated service based admission control strategy with an enhanced request classification scheme called Multi Phase Admission Control (MPAC) that can be integrated with MLF to bring more profits to the service that particularly benefits E-Commerce is proposed. The proposed scheme minimizes request processing time and maximizes the reward attained by processing requests that are likely to bring more profits to the service that particularly benefits E-Commerce websites. Simulations and experimentation show that differentiation in service results in a considerable improvement of performance in terms of reward earned for servicing the request and the same is detailed in section IV. The rest of the paper is organized as follows. Section II discusses the literature relevant for the motivation of the work. Sections III and IV analyze the performance of MPAC approach which focuses mainly on E- Commerce. Final conclusions are presented in section V.

In [6] Bhatti and Friedrich propose the Web QoS architecture for supporting server QoS and in particular tiered (i.e. differentiated) QoS levels. The Web QoS architecture contains several modules. The request classification module sets QoS attributes based on the filters and policies defined by the system administrator. After classification the admission control module determines whether the request is rejected or executed according to the scheduling policy of the class. If executed, then the classification attributes are used for request scheduling to determine how to enqueue and dispatch the request. Session management is used to provide session semantics and maintain session state for the stateless HTTP protocol. Session management is both based on a combination of cookies and IP source addresses. Resource scheduling ensures that high priority tasks are allocated and executed as high priority processes by the host operating system. The Web QoS architecture also supports integration with network QoS mechanisms such as reading and marking of IP Type of Service (ToS) header bytes, or Differentiated Services (DiffServ) fields.

In this paper, a simple nonasymptotic approximation for the Erlang B formula is considered. We find the sufficient condition when the approximation is relevant. The proposed result allows rejecting the previously used limited regime and considers the proportional differentiated admission control under finite network resources. Following this way, we get explicit formulas for PDAC problem. The proposed formulas deliver high-performance computing of network resources assignment under PDAC requirements. Thus, an e ffi cient method for proportional di ff erentiated admission control implementation has been provided.

Wireless mesh networks (WMNs) have gradually replaced wired networks due to its high transmission rate, low deployment cost, and extensive signal coverage. Their self-organized and self-configured features can greatly help in providing and maintaining connectivity among communities. WMNs are composed of mesh clients (MCs) and mesh routers (MRs), each of which communicates with one another by multi hop relays. The MRs are connected to the external wired networks through Internet gateways (IGWs), and each node in WMNs can act as either an MR or an MC. However, despite those great features, the provision of multimedia communications over WMNs requires that stringent quality of services (QoS) constraints be achieved compared with best effort data applications such as e-mail, www, and ftp, where packet delay and jitter have a lower impact. Thus, facilitating the handling of QoS requirements in order to provide admission control for multimedia traffic in the presence of data traffic becomes a very challenging problem over a WMN because of the available limited bandwidth .

A query that executes on a database system has to compete with concurrently executing queries for core, memory and software resources. Performance modeling theory has devel- oped over the years analytical tools to describe contention for core access using stochastic processes, e.g., product-form queueing network models [16]. This theory explains resource contention between different jobs when these are served under processor-sharing scheduling, an idealized version of round-robin where the quantum of time that each job receives is infinitesimal small. Product-form queueing net- work models are an appropriate abstraction to describe core contention, but they place some limitations on the analysis of real-world systems. For example, queries submitted to a database server may also experience blocking delays caused by constraints on the maximum software threading level. Thus, a query class with high parallelism level, but low core processing requirements, may still block the execution of other query classes if it saturates the threading limit constraint. These blocking delays add to the core contention overheads and can be difficult to model. We shall refer to such delays as interferences and, with the aim of defining a new admission control policy, we aim at characterizing and exploiting interferences between query classes.

Connection admission control (CAC) schemes are used to selectively limit the number of admitted calls from each traffic class to maximize network utilization while satisfying the QoS constraints [1]. In a cellular system, the QoS requirements for different services (e.g., voice, real-time video) require a CAC to limit the number of connections in each access network [2]. The CAC policy can either accept the connection request and allocate the resources accordingly or reject the connection request. In general, higher priority is given to the requests from handover users rather new users. From the user perspec- tive, abrupt termination of a connection is more annoy- ing than occasional blocking of new connection attempts.

In this section, we discuss several existing admission control algorithms in the area of wired, ad hoc, and wireless mesh networks. Traditional approaches like IntServ/RSVP and DiffServ [11] for QoS provisioning on the internet do not work well for wireless networks due to the inherent distinctions between the wired and wireless networks. For example, these approaches fail to address the challenges involved in estimating the available bandwidth required by the flow in a shared wireless medium. INSIGNIA [19] and SWAN [20] are both protocols that provide QoS guarantees by controlling the traffic in ad hoc network. INSIGNIA relies on in-band signaling by piggybacking the control infor- mation on data. This in-band signaling allows INSIGNIA to quickly reestablish flow state when topology changes occur. SWAN, an alternative to INSIGNIA, is characterized by its improved scalability. Here, the per-flow information is not stored in the intermediate nodes and therefore the protocol avoids complex signaling which makes the system more simple and scalable. However, the downside of both these schemes is that neither takes into account the fact that the communication from one node may consume the resources of the neighboring nodes in addition to its local resources.

We will show that both the forced termination probability and the interference created by the operation of SUs upon PUs can be controlled by limiting the access of SUs. This finding motivated us to design an admission control scheme for SUs that is able to limit simultaneously both the forced termination probability of SUs and what we define as the probability of interference. We show that both the forced termination probability and the interference caused to PUs are highly dependent on system parameters and on the arrival processes and service distributions. However, the proposed scheme is self-adaptive and does not require any configuration parameters beyond the targeted QoS objec- tives. Besides, it does not rely on any particular assumptions on the traffic characteristics; that is, it can operate with any arrival process and distribution of the session duration.

In a code division multiple access (CDMA) system, quality- of-service (QoS) requirements rely on interference mitiga- tion schemes and resource management, such as power con- trol, multiuser detection, and admission control (AC) [1– 3]. Recently, the problem of ensuring QoS by integrating the design in the physical layer and the admission control (AC) in the network layer is receiving much attention. In [4, 5], an optimal semi-Markov decision process (SMDP)- based AC policy is presented based on a linear-minimum- mean-square-error (LMMSE) multiuser receiver for constant bit rate traffic and circuit-switched networks. In [6], optimal admission control schemes are proposed in CDMA networks with variable bit rate packet multimedia traffic.

The implementation of efficient call admission control (CAC) algorithms is useful to prevent congestion and guarantee target qual- ity of service (QoS). When TCP protocol is adopted, some inefficiencies can arise due to the peculiar evolution of the congestion window. The development of cross-layer techniques can greatly help to improve efficiency and flexibility for wireless networks. In this frame, the present paper addresses the introduction of TCP feedback into the CAC procedures in different nonterrestrial wireless architectures. CAC performance improvement is shown for different space-based architectures, including both satellites and high altitude platform (HAP) systems.

The handover target cell selection algorithm for WiMAX network based on the effective capacity estimation and neighbor advertisement, which effectively avoids the Ping-Pong effect and handover synchronization effect [10]. The standards only define the ASN GW relocation procedures without specifying when the ASN GW relocation should be performed. That incorporates traditional Admission Control (AC) and Wiener Process (WP)-based prediction algorithms to determine when to carry out ASN GW relocation. Location-aware scanning includes scanning and network re-entry, where it reduces interruption of data transmission during handover by decreasing both the scanning delay and the number of the neighbor BSs to be scanned. The MS finds its position using GPS and selects the target BS based on the distance. A Pre- Coordination Mechanism (PCM) for supporting fast handover in WiMAX networks is designed [11]. The distance between the BS and the MSS is measured and the time of handover occurrence is predicted. A Mobile Station (MS) - controlled fast MAC-layer handover (HO) scheme based on the Received Signal Strength (RSS) from any Base Station (BS) to reduce the HO latency in Mobile WiMAX is proposed

Since the network accepts or rejects the connection request and this establishes the eciency of the network, the accept/reject decision is a critical one (since maximal use of network resources is a main objective of network operators). The accept/reject decision is based on whether or not the network would be able to provide the required QOS for the requesting connection while maintaining the QOSs already committed to for the existing connections. Call Admission Control (CAC) algorithms are executed by network switches as connection requests arrive and are responsible for achieving

Radio resource management (RRM) plays a major role in Quality of Service (QoS) provisioning for wireless communication systems. It includes flow control , resource allocation (RA), congestion control, Call admission control (CAC) etc in order to control the amount of the assigned resources to each user with the objective of maximizing some function such as the total network throughput, total resource utilization, or total network revenue, subject to some constraints such as the maximum call blocking/dropping rate and/or the minimum signal to interference ratio. The performance of RRM techniques has a direct impact on each user‟s individual performance and, more importantly, on the overall network performance [5].

The routing and admission control is studied jointly in this paper, where a novel routing protocol is merged with multi-homing to get better QoS for new and handoff calls in WMN. Handoff algorithms proposed in the litera- ture find a new path for the handoff call which is completely disjointed with the old primary path, and reject the calls in case of highly congested networks. Our proposed algorithm introduces a new routing approach for new and handoff calls which is based on finding a maximally jointed path with the old primary path and enable the multi-homing feature in case of highly congested network. Our proposed algorithm is compared with four dif- ferent scenarios where multi-homing and joint routing is enabled or disabled. An MDP markov model is intro- duced and solved using value iteration method to find a near optimal solution. Our proposed algorithm, MDACR, outperforms other algorithms proposed in the literature in terms of handoff delay, new and handoff calls blocking probability, and number of hard handoffs especially in the case of highly congested networks. MDACR gives the mobile user with seamless handoff approach with higher admitted users in the network.

SunethNamal, KavehGhaboosi, Mehdi Bennis, Allen B. MacKenzie and MattiLatva-aho introduced an algorithm based on Reinforcement Learning for slot allocation to the traffic streams on different sub-carriers to be employed by each femtocell access point in order to mitigate the interference among femtocells and the underlaid macrocell [18]. To allocate sub-carriers to an incoming traffic, a femtocell maintains a counter for each sub-carrier and stochastically counts it down using the outage probability perceived on the sub-carrier. The traffic is assigned to a set of sub-carriers, for which the counter reaches zero within a predefined time interval. Once traffic streams are assigned to the sub- carriers, each femtocell access point independently runs an algorithm based on reinforcement learning to perform slot allocation for the traffic streams in each sub-carrier, which is meant for further interference mitigation among femtocells and the underlaid macrocell.Proposed admission control mechanism, is entirely stream oriented, which allows users to have more than one simultaneous traffic streams with different QoS requirements and makes the accounted system model be closer to the practical networks.