User Allocation in Multi-System, Multi-Service Scenarios: Upper and Lower Performance Bound of Polynomial Time Assignment Algorithms

Abstract

In this paper we cover the problem of how users of different service classes should be assigned to a set of radio access technologies (RAT). All RAT have overlapping coverage and the aim is to maximize a weighted sum of assignable users. Under the constraint that users cannot be split between multiple air-interfaces the problem is identified as NP-complete. In the first part of the paper we derive upper and lower bounds of polynomial assignment algorithms. Using Lagrangian theory and continuous relaxation we show for polynomial assignments that in scenarios with M air-interfaces there are at most M users less assigned than in the optimum solution. In the second part we present an algorithm and compare its performance to standard load-balancing strategies.

Optimal dynamic admission control in heterogeneous networks

“…For this, the system is equipped with an heterogeneous access management (HAM) device which coordinates the resource sharing by following an admission control policy. For orthogonal air interfaces and for air interfaces where the resource costs depend only on the sum of interference and not on its compilation, this resource sharing problem can be formulated by associating a capacity value with each air interface and assigning to each user a set of cost values for the different air interfaces [1]. These cost values reflect the amount of resources required to support a user according to his requirements in a certain air interface.…”

Decentralized Utility Maximization in Heterogeneous Multicell Scenarios with Interference Limited and Orthogonal Air Interfaces

“…Reasons include different carrier frequencies and corresponding channel models of RATs, base station positioning, different interference situations and sensitivity to it. A concept that considers all earlier mentioned factors, like the system load, service class, interference situation, characteristics of the RAT, and users' positions, is the costbased approach, introduced and analyzed in [3,4]. There, it was observed that all characteristics can be bundled together in one cost parameter per user and RAT which suffice to calculate a close to optimum assignment that maximizes the total number of supportable voice users under static conditions.…”

“…In this paper, we analyze in which way users of different service classes should be assigned in a heterogeneous scenario, thereby extending ideas from [3,4]. Users request either a fixed minimum data rate, for example, as needed for voice services, or unconstrained best-effort (BE) data services.…”