1 Existing base station (BS) assignment methods in cellular networks are mainly driven by radio conditions since it is assumed that the limiting factor is the air interface. This assumption has been proven to be very reasonable when circuit voice was the dominant service and backhaul capacity provisioning in BS accounting for the peak rate of the radio link was an economically feasible option. However, as traffic continues increasing and enhanced air interfaces are been deployed, a growing concern is that also the mobile backhauling can become a bottleneck in certain deployment scenarios. In this paper we present a BS assignment algorithm designed to optimize radio resource usage while simultaneously considering potential capacity limitations in mobile backhauls. The BS assignment problem is formulated using a cost-based framework and mapped into a Multiple-Choice Multidimensional Knapsack Problem (MMKP) that is solved by means of a heuristic algorithm with polynomial time. The proposed algorithm is evaluated and compared to two schemes based exclusively on radio conditions. Simulation results show that the proposed algorithm can assign more users than existing algorithms without violating radio and transport constraints in partially backhaul limited scenarios.

Abstract-This paper analyses the possibility to exploit opportunistic spectrum access (OSA) for short-range radio communication systems within indoor locations in dense urban areas. In particular, considering the service area of a primary system devoted to providing outdoor coverage in a dense urban scenario, the percentage of indoor locations where the secondary users can reuse the primary frequency band without disturbing the primary system or being disturbed is estimated. The analysis considers heterogeneous path loss models for the primary and secondary systems encompassing the characterization of outdoor, indoor and building penetration losses. Obtained results quantify how aspects like the location of the primary network elements and the considered interference margins to protect primary transmissions impact on the spatial availability of the primary band within the interior of the buildings.

In mobile access networks, base station (BS) assignment mecbanisms are mainly driven by radio conditions since it is generally assumed tbat tbe limiting factor is tbe air interface. Tbis assumption bas been proven to be very reasonable wben circuit voice was tbe dominant service and backbaul capacity provisioning accounting for tbe peak rate at tbe BSs was an economically feasible option. However, as more efficient air interface tecbnologies are introduced along witb bigber data rate services, a growing concern is tbat tbe transport part of tbe mobile network can also represent a bottleneck. In tbis paper we analyze a BS assignment strategy tbat simultaneously exploits load balancing in botb tbe radio interface and tbe transport backbaullinks. Tbe BS assignment problem is solved by means of Simulated Annealing beuristics under different deployment scenarios comprising partially-limited backbaul Radio Access Networks (RANs) and tbe presence of traffic botspots. Results acbieved for tbe proposed BS assignment strategy are compared to tbose obtained by common strategies sucb as minimum patb loss (MPL) and load balancing radio (LBR).

Cell selection in mobile radio access networks is mainly driven by efficient resource usage of the air interface. In this paper we add a new dimension to the cell selection problem by considering also the current occupancy of transport resources in the backhaul part of the network since, it is believed that, with the introduction of high speed services, this backhaul network can be a limiting factor. In such cases, we demonstrate that a cell selection algorithm using transport status information provides significant benefits over traditional schemes exclusively based on radio criteria, even under those scenarios where the selection of a cell other than the best radio server can be thought as not adequate in terms of radio resource management (e.g. single-layer/single-RAT deployments). The cell selection problem is analytically formulated and developed by means of a multidimensional Markov chain.

Abstract-The optimization of the base station (BS)Thus, an assignment procedure which is based on radio assignment problem in mobile access networks is a primary task parameters may assign users to base stations with an towards enabling efficient utilization of network resources. So overloaded backhaul since its assignment criteria do not far, this problem has been mainly studied in terms of air consider the backhaul load of BSs. Under this context, in a interface optimization. In this paper, we present a novel BS previous work [6] we proposed an assignment method that assignment strategy that integrates backhaul constraints in the allocates users to BSs taking into account the availability of user assignment criterion. The motivation of this strategy is the resources in the air interface and the backhaul network.fact that in some scenarios the backhaul can become the network bottleneck. The BS assignment problem or user allocation Illustrative results, obtained assuming a single class of problem is formulated using a utility-based framework. We take mobiles with a fixed transmission rate constraint, indicate that into consideration key aspects such as the revenue associated to a backhaul-aware strategy lead to a higher number of feasible each type of service along with the resource consumption in user assignments. terms of both radio and backhaul resources. Results are given inIn this paper we extend the analysis reported in [6] by a multi-service scenario for guaranteed rate services.evaluating the proposed user allocation algorithm in more complex scenarios where data users have varied quality of I. INTRODUCTION service (QoS) requirements. We focus on multiservice mobile The growing popularity of data services in mobile networks networks able to guarantee different data rates to users and requires more advanced strategies to manage the scarcity of where bottlenecks can appear in both radio and backhaul radio resources efficiently. Enhanced methods to control segments. The problem consist in assigning users to base users' connectivity to the network play an important role in stations so that its rate requirement can be fully satisfied, the radio resource management (RRM) framework as they subject to radio and backhaul constraints of each BS. Users facilitate an efficient use of radio resources.that demand different rates are differentiated by means of a This paper addresses the base station (BS) assignment profit associated to the corresponding service class. An utility problem that is in charge of determining the serving BS to function is defined to quantitatively translate user/operator each user in the system. This problem has been addressed so benefits in terms of the amount of radio resources each user far mainly from the radio perspective. This is the case of [1]-requires and the profit that it will provide to the operator. [3] that deal with the combined problem of BS assignment andThe BS assignment problem is formulated as an resource allocation, where the primary idea is to determine the optimization ...