Post-deployment tuning of UMTS cellular networks through dual-homing of RNCs

Abstract

In conventional UMTS cellular networks, during deployment usually a set of NodeBs is assigned to one Radio Network Controller (RNC), and a set of RNCs to one Serving GPRS Support Node (SGSN) for data services, as weD as to one Mobile Switching Centre (MSC) for voice services. Operators thus far have considered single-homing of RNCs to MSCs/SGSNs (i.e., many-to-one mapping) with an objective to reduce the total cost over a fIXed period of time. However, a single-homing network does not remain cost-effective any more when subscribers later on begin to show specific inter-MSC/SGSN mobility patterns (say, diurnality of office goers) over time. This necessitates post-deployment topological extension of the network in terms of dual-homing of RNCs, in which some specific RNCs are connected to two MSCs/SGSNs via direct links resulting in a more complex many-to-two mapping structure in parts of the network. The partial dual-homing attempts to increase link cost minimally and reduce handoff cost maximaDy, thereby significantly reducing the total cost in a post-deployment optimal extension. In this paper, we formulate the scenario as a combinatorial optimization problem and solve the NP-Complete problem using two meta-heuristic techniques, namely Simulated Annealing (SA) and Tabu search (TS). We then compare these techniques with a novel optimal heuristic search method that we propose typically to solve the problem. The comparative results reveal that, though aD of them perform equally well for small networks, for larger networks, the search-based method is more efficient than meta-heuristic techniques in finding optimal solutions quickly.This can be addressed in post deployment planning phase by splitting cells (where capital expenditure as well as hand-off cost will increase) or by redefining the connectivity of cells and switches. The third case may arise due to a gradual change in mobility pattern of the existing subscriber base over a long period of time [6]. This problem can be addressed by regrouping cells into new clusters i.e., by changing the connectivity of NodeBs to RNCs and RNCs to MSCs/SGSNsHowever, this cannot take care of situations where handoff increases with no increase in total traffic due to periodic (temporal) changes of subscribers' locations. If there is a clear pattern of this temporal mobility of subscribers, a multi-homing consideration (where many NodeBs are connected to one RNC, and many RNCs are connected to one MSC/SGSN) will be a useful strategy in post deployment tuning stage. Obviously, the multi-homing concept can be implemented at two levels, namely, in the first level, multi-homing of NodeBs, and, in the second level, multi-homing of RNCs. In this paper, we have considered dual-homing of RNCs, where some RNCs (to be decided optimally) are connected to two MSCs/SGSNs (as shown in Fig. 1) to reduce handoff cost, unlike single homing where one RNC is connected to one MSC/SGSN only. In order to achieve an optimal selection of RNCs from the set of potential RNCs to be dual-homed, we have prop...

An Analysis of Traffic and Throughput for UMTS Packet Core Networks

“…Ludwin (2002) has a systematic review for GPRS and UMTS network planning work in which the dimensioning work also stresses the radio interfaces. Similar studies by Sadhukhan et al (2009) and Ting (2008) also introduce planning methods applied to GPRS or UMTS PS network from the radio access network perspective. Neruda and Bestak (2008) summarizes the evolution path from GSM, UMTS to IMS from the aspect of network entities so that service providers will be able to progressively migrate from GSM to UMTS and IMS.…”

Mobility management protocol in dual-homed UMTS networks

“…COMPARISON OF MESSAGE FLOW Dual homed networks convert complex handoffs into simple handoffs. Additional cost is required to establish the secondary links that are used in dual homed networks, but the savings from handoff reduction are significant [4]. The savings in handoff cost comes due to reduction of control signals in the mobility management protocol.…”

“…One such post planning problem is where new call traffic does not increase but handoff traffic does due to a gradual change in mobility pattern of the existing subscriber base over time. This situation where handoff increases with no increase in total traffic due to temporal changes of subscribers' locations is considered in [4] with the help of dual homing of RNCs. In dual homing, one RNC may be connected to more than one MSC/SGSN (to reduce handoff cost), unlike single homing where one RNC is connected to one MSC/SGSN only.…”

“…In dual homing, one RNC may be connected to more than one MSC/SGSN (to reduce handoff cost), unlike single homing where one RNC is connected to one MSC/SGSN only. In [4] the authors have not considered any protocol related issues to implement the dual homing of RNCs. We have proposed a modification of the existing signalling protocol sequence [5] to take care of handoff handling under the new architecture of dual homing of RNC.…”

Improving Quality of Experience of Subscribers through Post Deployment Network Planning in UMTS Cellular Networks

“…In this context the prop i.e., network infrastructure needs to be planned in such a manner so that it can adapt the changes in subscribers' pool. This makes the post deployment networking (Sadhukhan et al, 2009) planning more important. The post deployment network planning can be done with respect to a parameter or a combination of parameters.…”