Modeling and performance evaluation of the eICIC/ABS in H-CRAN

International audienceIn this paper, we propose mathematical models to evaluate the performance of the interference remediation technique eICIC/ABS (enhanced Inter-Cell Interference Coordination / Almost Blank Sub-frame) in the context of Heterogeneous Cloud based Radio Access Networks (H-CRAN) architecture and 5G networks. The objective is to propose a dynamic resource management tool to ease decisions on the activation/deactivation of micro-cells as well as on the distributions of subframes among macro and micro cells. First, we propose a Markov chain based model that fits the behavior of the considered scheme and allows the analysis of the cell throughput according to traffic load, radio conditions and the distribution of available resources among macro and micro cells. Then, we propose an approximation model with a closed form formula. The two models are validated and evaluated in terms of accuracy and computation time. Numerical results are compared to matlab simulations that reproduce realistic radio conditions. Results show that both models are accurate. However, the closed form approximation is less complex and provides faster results

Analytical Modeling of Downlink CoMP in LTE-Advanced

International audienceIn this paper, we discuss several Coordinated Multi-Point (CoMP) schemes proposed for LTE-Advanced systems. We investigate their benefits in a multi-antenna beamforming system where multiple cells may share their resources and jointly coordinate their transmissions to improve the performance at cell edge and the overall system capacity. We evaluate the system performance by combining flow-level analysis with numerical results from LTE-Advanced network simulator. We show that the intra-site coordination brings significant gains in beamforming systems, especially with the joint transmission scheme where the user throughput and the system capacity are improved

Performance evaluation of intra-site coordination schemes in cellular networks

International audienceIn this work, we develop performance evaluation models for some intra-site coordination schemes in cellular networks, with a focus on Multi-flow transmission in HSPA+. We first focus on a static scheme where coordination is always performed for all users in the overlapping region of two cells. Through the analysis of a flow-level model, we show that this scheme indeed improves the cell-edge throughput at low loads but may make the system unstable at high loads, due to the suboptimal allocation of radio resources. We notice also that these results are very sensitive to the coordination threshold. We thus investigate a dynamic scheme which performs coordination according to resource availability in the site and show that this scheme outperforms the static one at all traffic loads independently of the coordination threshold. Additional results demonstrate an efficient load balancing ability across cells. We finally analyze how our models extend to the case of opportunis-tic scheduling schemes, like Proportional Fair, and show the impact of these schemes on the coordination gains

Flow-Level Performance of Intra-site Coordination in Cellular Networks

International audienceIn this paper, we assess the ability of intra-site coordination schemes to combat inter-cell interference in cellular networks. We first focus on the static scheme proposed by the 3GPP standards where coordination is always performed in hand-over regions. Through the analysis of a flow-level model, we show that this scheme indeed improves cell-edge throughput at low loads but may make the system unstable at high loads, due to the suboptimal allocation of radio resources. We then propose a dynamic scheme where coordination decisions depend on the loads of the different sectors. Results show that this dynamic scheme behaves like the static one at low loads, outperforms it at medium loads and preserves the stability region of the network at high loads

Capacity gains from multipoint single frequency transmission in HSPA+

International audienceHigh Speed-Single Frequency Network (HS-SFN) is one of the possible multipoint transmission techniques proposed in the 3GPP standard for High Speed Downlink Packet Access (HSDPA) in order to improve network performance, especially at the cell edge. It allows neighboring cells to transmit simultaneously the same data stream to a User Equipment (UE) in the Handover region (HO). In order to evaluate the user-level performance of this technique, we develop a method based on network simulation coupled with Markov chain analysis. It shows that when the HS-SFN technique is performed in the HO region between adjacent cells, the user data rates increase significantly. However, this is true only when involved cells are partially loaded, which is not always the case. We thus propose an optimized approach that adapts the coordination area based on the average offered traffic observed in the network. Network performance is then improved at any load

Flow-level modeling of multi-user beamforming in mobile networks

International audienceAmong the several features that are foreseen for increasing the capacity of cellular systems, Multi-user multiple-input multiple-output (MU-MIMO) is considered as a key en-abling technology. Particularly, MU-beamforming is a powerful means of increasing the system capacity and throughput by creating several spatial signals to different users on the same time/frequency resource. In this paper, we develop an analytical model for MU-beamforming based on queuing theory combined with network simulations. The proposed framework is used for evaluating the potential gains in terms of capacity and throughput in LTE-Advanced system. Several scenarios are studied, with and without beamforming. Results show an important gain of SU-beamforming over the classical system without beamforming and a further gain of MU-beamforming, especially at high loads

Multi-Flow Transmission and Carrier Aggregation Inter-Operation in HSPA+ Advanced

International audienceCarrier aggregation and multi-flow transmission are among the most important features of HSPA+. While the former allows users to be served simultaneously by several carriers in the same sector, the latter enables adjacent sectors to simultaneously schedule different data streams to the same user in their over-lapping region. In this paper, we investigate the inter-operation of these two features. We evaluate the flow-level performance using a method based on network simulation coupled with Markov chain analysis. Results in single-carrier mode show an improvement in throughput at low load and an efficient load balancing across sectors at high load. In multi-carrier mode, we show that coordination is no more recommended since it does not achieve any throughput gain over the classical multi-carrier system. This is due to the actual status of the standard that limits the number of carriers that can be used for the multi-flow transmission to two. However, if this restriction is released in the standard, our results show that multiflow transmission would bring significant gains