Fairness in Communication and Computer Network Design

In communication networks, fair sharing of resources is an important issue for one main reason. The growth of network capacity is in general not matching the rapid growth of traffic. Consequently, the resources consumed by each user have to be limited. This implies that users cannot always be assigned the end-to-end bandwidth they ask for. Instead, the limited network resources should be distributed to users in a way that assures fair end-to-end bandwidth assignment among them. Obtaining fairness between network users and at the same time assuring efficient network utilization, is a source of non-trivial network optimization problems. Complicating factors are that each user has limited access to the (limited) network resources and that different users require and consume different amounts and types of resources. In this thesis different types of optimization problems associated with fair resource sharing in communication networks are studied. Initially, the notions of max-min fairness, proportional fairness, alpha-fairness etc., are put in a formal framework of fair rational preference relations. A clear, unified definition of fairness is presented. The theory is first applied to different types of allocation problems. Focus is put on convex and non-convex max-min fair traffic allocation problems, and a difference in difficulty between the two groups of problems is demonstrated. The studies are continued by an investigation of proportionally fair dimensioning. Two different cases are studied -- a simpler, when no resilience to failures is required, and a more complicated, assuming the possibility of link failures. In the context of fair sharing of the resources of a communication network, this thesis presents several original theoretical findings as well as solution algorithms for the studied problems. The results are accompanied by numerical results, illustrating algorithm efficiency for virtually all of the studied problems

Selective Fair Scheduling over Fading Channels

Imposing fairness in resource allocation incurs a loss of system throughput, known as the Price of Fairness ($PoF$). In wireless scheduling, $PoF$ increases when serving users with very poor channel quality because the scheduler wastes resources trying to be fair. This paper proposes a novel resource allocation framework to rigorously address this issue. We introduce selective fairness: being fair only to selected users, and improving $PoF$ by momentarily blocking the rest. We study the associated admission control problem of finding the user selection that minimizes $PoF$ subject to selective fairness, and show that this combinatorial problem can be solved efficiently if the feasibility set satisfies a condition; in our model it suffices that the wireless channels are stochastically dominated. Exploiting selective fairness, we design a stochastic framework where we minimize $PoF$ subject to an SLA, which ensures that an ergodic subscriber is served frequently enough. In this context, we propose an online policy that combines the drift-plus-penalty technique with Gradient-Based Scheduling experts, and we prove it achieves the optimal $PoF$. Simulations show that our intelligent blocking outperforms by 40$\%$ in throughput previous approaches which satisfy the SLA by blocking low-SNR users

Fair resource allocation schemes and network dimensioning problems, Journal of Telecommunications and Information Technology, 2003, nr 3

Resource allocation problems are concerned with the allocation of limited resources among competing activities so as to achieve the best overall performances of the system but providing fair treatment of all the competitors. Telecommunication networks are facing the increasing demand for Internet services. Therefore, a problem of network dimensioning with elastic traffic arises which requires to allocate bandwidth to maximize service flows with fair treatment of all the services. In such applications, the so-called max-min fairness (MMF) solution concept is widely used to formulate the resource allocation scheme. This guarantees the fairness but may lead to significant losses in the overall throughput of the network. In this paper we show how multiple criteria optimization concepts can be used to generate various fair resource allocation schemes. The solution concepts are tested on the network dimensioning problem and their abilities to model various preferences are demonstrated

Samoorganiziranje u autonomnoj arhitekturi za pružanje diferenciranih usluga primjenom algoritma za balansiranje prometa

This paper is about the role of a heuristic algorithm for load balancing that can be incorporated in Multi-Protocol Label Switching/ Differentiated Services (MPLS/DS) networks based on self-management principles for automated traffic configuration. Delivery of Quality of Services (QoS) differentiation according to specific service level agreements, Service Level Agreement (SLA), has to be in relation to resource management and bandwidth allocation, to ensure better end-to-end QoS provisioning and to avoid traffic congestion. To ensure simultaneous traffic flows with different priorities we need some load-balancing procedure. It could start much earlier than usual, possibly during SLA negotiation. If SLA creation is supported by load control mechanism it can ensure better performances of the network in the moment of service invocation. LSP (Label Switching Path) creation could be influenced by former contracted SLAs and such approach could be more effective than pure routing technique based on the shortest path algorithm (LSP creation in the moment of service invocation). So we propose application of heuristic algorithm tested on numerical examples with maximum M routers on the path and with differentiation of N service classes. Further, we introduced some capacity state restrictions in the process of network optimization, considering different algorithm options. We compared their performances, especially the algorithm complexity that is very important for efficient load control in huge networks.Članak opisuje ulogu heurističkog algoritma za balansiranje opterećenja i dimenzioniranje prometa u MPLS/DiffServ mreži na načelu samoorganizacije i automatske konfiguracije. Ostvarenje QoS usluga mora biti u skladu s postojećim ugovorom za kvalitetu usluge (SLA), sklopljenim između korisnika i operatera, ali tako da se omogući upravljanje resursima mreže izbjegavajući moguća zagušenja. Da bi osigurali simultane prometne tokove uz razlikovanje kvalitativne razine, nužno je osigurati balansiranje prometa. Takvo balansiranje mreže može započeti i znatno ranije, moguće već u trenutku pregovaranja pri sklapanju SLA. Ako je ono podržano kontrolom mogućeg zagušenja mogu se značajno poboljšati QoS jamstva i uravnoteženost mreže. Kreiranje LSP puta s obzirom na prijašnje ugovoren (rezerviran) promet bilo bi bolje od samog usmjeravanja na načelu najkraćeg puta (usmjeravanje u trenutku pokretanja usluge). Za tu je namjenu u radu predložena primjena heurističkog algoritma testiranog na mnogim numeričkim primjerima s maksimalno M usmjerivača na putu s kraja-na kraj domene i s maksimalno tri vrste (N=3) različitih kvalitativnih razina (klase prometa). Razmatrana su daljnja poboljšanja algoritma u ograničavanju stanja kapacitivnih točaka u postupku mrežne optimizacije, tj. testirane su i uspoređene razne opcije algoritma. Neke od njih pokazuju značajno smanjenje složenosti uz zadovoljavajuću kvalitetu ostvarenih rezultata, što je važno za kontrolu opterećenja u velikim mrežama

Dimensionerings- en werkverdelingsalgoritmen voor lambda grids

Grids bestaan uit een verzameling reken- en opslagelementen die geografisch verspreid kunnen zijn, maar waarvan men de gezamenlijke capaciteit wenst te benutten. Daartoe dienen deze elementen verbonden te worden met een netwerk. Vermits veel wetenschappelijke applicaties gebruik maken van een Grid, en deze applicaties doorgaans grote hoeveelheden data verwerken, is het noodzakelijk om een netwerk te voorzien dat dergelijke grote datastromen op betrouwbare wijze kan transporteren. Optische transportnetwerken lenen zich hier uitstekend toe. Grids die gebruik maken van dergelijk netwerk noemt men lambda Grids. Deze thesis beschrijft een kader waarin het ontwerp en dimensionering van optische netwerken voor lambda Grids kunnen beschreven worden. Ook wordt besproken hoe werklast kan verdeeld worden op een Grid eens die gedimensioneerd is. Een groot deel van de resultaten werd bekomen door simulatie, waarbij gebruik gemaakt wordt van een eigen Grid simulatiepakket dat precies focust op netwerk- en Gridelementen. Het ontwerp van deze simulator, en de daarbijhorende implementatiekeuzes worden dan ook uitvoerig toegelicht in dit werk

Active Queue Management for Fair Resource Allocation in Wireless Networks

This paper investigates the interaction between end-to-end flow control and MAC-layer scheduling on wireless links. We consider a wireless network with multiple users receiving information from a common access point; each user suffers fading, and a scheduler allocates the channel based on channel quality,but subject to fairness and latency considerations. We show that the fairness property of the scheduler is compromised by the transport layer flow control of TCP New Reno. We provide a receiver-side control algorithm, CLAMP, that remedies this situation. CLAMP works at a receiver to control a TCP sender by setting the TCP receiver's advertised window limit, and this allows the scheduler to allocate bandwidth fairly between the users

Cloud Empowered Cognitive Inter-cell Interference Coordination for Small Cellular Networks

In this article, we present a Cloud empowered Cognitive Inter-Cell Interference Coordination (C2-ICIC) scheme for small cellular networks. The scheme leverages a recently proposed cloud radio access network (C-RAN) architecture for enabling intra-tier coordination and relaxes the need for inter-tier coordination by adopting the phantom cell architecture. Employing tools from stochastic geometry, we characterize the downlink success probability for a Mobile User (MU) scheduled under the proposed coordination scheme. It is shown that, compared to un-coordinated scheduling, significant performance gains can be realized in ultra dense small cell deployment scenarios under the proposed C2-ICIC scheme. This is attributed to the robust interference protection provisioned by the scheme. It is demonstrated that the gains are particularly large for the users experiencing a weak received signal strength. Indeed, for these users, the received signal-to-interference ratio (SIR) can only be improved by reducing the experienced aggregate co-channel interference. The closed-form expression derived for the downlink success probability is employed to quantify the link level throughput under the proposed scheme. Finally, we briefly explore the design space of the C2-ICIC scheme in terms of interference protection cap which determines both the downlink throughput of the MU scheduled in the coordination mode and the transmission opportunity for the co-channel small cells