Pantelis Monogioudis

Algorithms for Enhanced Inter-Cell Interference Coordination (eICIC) in LTE HetNets

The success of LTE heterogeneous networks (HetNets) with macrocells and picocells critically depends on efficient spectrum sharing between high-power macros and low-power picos. Two important challenges in this context are: 1) determining the amount of radio resources that macrocells should offer to picocells, and 2) determining the association rules that decide which user equipments (UEs) should associate with picos. In this paper, we develop a novel algorithm to solve these two coupled problems in a joint manner. Our algorithm has provable guarantee, and furthermore, it accounts for network topology, traffic load, and macro-pico interference map. Our solution is standard compliant and can be implemented using the notion of Almost Blank Subframes (ABS) and Cell Selection Bias (CSB) proposed by LTE standards. We also show extensive evaluations using RF plan from a real network and discuss self-optimized networking (SON)-based enhanced inter-cell interference coordination (eICIC) implementation.

Learning-based uplink interference management in 4G LTE cellular systems

LTEs uplink (UL) efficiency critically depends on how the interference across different cells is controlled. The unique characteristics of LTEs modulation and UL resource assignment poses considerable challenges in achieving this goal because most LTE deployments have 1:1 frequency reuse, and the uplink interference can vary considerably across successive time-slots. In this paper, we propose LeAP, a measurement data-driven machine learning paradigm for power control to manage uplink interference in LTE. The data-driven approach has the inherent advantage that the solution adapts based on network traffic, propagation, and network topology, which is increasingly heterogeneous with multiple cell-overlays. LeAP system design consists of the following components: 1) design of user equipment (UE) measurement statistics that are succinct, yet expressive enough to capture the network dynamics, and 2) design of two learning-based algorithms that use the reported measurements to set the power control parameters and optimize the network performance. LeAP is standards-compliant and can be implemented in a centralized self-organized networking (SON) server resource (cloud). We perform extensive evaluations using radio network plans from a real LTE network operational in a major metro area in the US. Our results show that, compared to existing approaches, LeAP provides 4.9× gain in the 20th percentile of user data rate, 3.25× gain in median data rate.

Deprioritization of heavy users in wireless networks

The explosive demand for wireless data services that followed the introduction of application phones continues to create significant challenges for mobile operators. Measurement campaigns indicate that the consumption of wireless network capacity follows a power law where 20 percent of the users consume more than 80 percent of capacity. This creates unfairness among users in terms of the data volume they are allowed to consume and, more important, during congested periods of time it degrades the quality of experience of all the users. As a response, many operators are attempting to control demand by gradually moving away from unlimited data plans with the introduction of volume caps and tiered charging. Many operators throttle the heavy users after they have exceeded their cap, and consider doing the same during times of congestion. This article evaluates the concept of deprioritization of heavy users in wireless networks for congestion management, the difference between deprioritization and throttling, and the enabling technologies to implement the feature in real-world networks.

EV-DO revision C: Evolution of the CDMA2000 ∗ data optimized system to higher spectral efficiencies and enhanced services

Wireless packet data services are poised to be a major growth area, as wireless voice services have reached a fair level of maturity. An effort by the 3rd Generation Partnership Project 2 (3GPP2) standards body to continue to develop the successful data-optimized 1x EV-DO high rate packet data (HRPD) 3G system is under way. Alcatel-Lucent along with partners is proposing several novel techniques beyond the state of the art. Some of the key technologies are orthogonal frequency code division multiple access (OFCDMA), multi-carrier as well as wideband transmission, both frequency division duplex (FDD) and time division duplex (TDD) modes, multiple antenna techniques such as space division multiple access (SDMA) and multiple input multiple output (MIMO), interference mitigation techniques, and frequency domain interference cancellation. These are described in detail along with the resulting benefits. The design goals are to provide flexibility, backward compatibility (both loose and strict), a boost in the spectral efficiency and peak rates, a reduction in latency for real-time services, and a reduction in complexity in the base stations (BS) and mobile stations (MS). In this paper, we describe the underlying design philosophy and the associated technologies of 1x EV-DO Revision C with a focus on Alcatel-Lucents contribution and provide associated performance results. The standard is expected to be completed in 2Q 2007.