Kari Horneman

Network energy saving technologies for green wireless access networks

The energy consumption problem in the mobile industry has become crucial. For the sustainable growth of the mobile industry, energy efficiency (EE) of wireless systems has to be significantly improved. Plenty of efforts have been invested in achieving green wireless communications. This article provides an overview of network energy saving studies currently conducted in the 3GPP LTE standard body. The aim is to gain a better understanding of energy consumption and identify key EE research problems in wireless access networks. Classifying network energy saving technologies into the time, frequency, and spatial domains, the main solutions in each domain are described briefly. As presently the attention is mainly focused on solutions involving a single radio base station, we believe network solutions involving multiple networks/systems will be the most promising technologies toward green wireless access networks.

Cooperative distributed optimization for the hyper-dense small cell deployment

The fifth generation mobile networks will be developed to improve area spectral and energy efficiency, and provide uniform user experience. Hyper-dense small cell deployment can move devices closer to the wireless network and satisfy 5G system requirements. The main challenge of this network deployment results from the random deployment, dynamic on-off, flexible connection to cellular core networks, and flat system architecture of 5G systems. Therefore, conventional network planning and radio resource management, which depend on a central control node, cannot be applied to small cell networks. In this article some cooperative distributed radio resource management algorithms for time synchronization, carrier selection, and power control are discussed for hyper-dense small cell deployment.

Providing enhanced cellular coverage in public transportation with smart relay systems

This paper introduces a notion of coordinated and cooperative relay systems (CCRS) for providing enhanced cellular coverage in highly populated public transportation such as passenger trains, cruise ships, etc. This notion considers a closed group of relay nodes and cells thereof, deployed together for particular service area of interest, as a new interconnected-and-extended network entity of advanced cellular systems — the CCRS. The CCRS may be set up on the run and connected to donor cellular network(s) with multiple mobile wireless backhaul links in a coordinated and controlled manner. This is in order to optimize, for examples, duplexing operation in relaying, load balancing and capacity sharing, as well as mobility management of the CCRS which serves a huge number of mobile users aboard of transportation. This paper addresses challenges as well as architecture alternatives and enhancements for incorporating the CCRS into advanced cellular networks such as 3GPP LTE-A systems. This paper also shows some methods to explore notable amounts of time-space and user diversities associated with the CCRS and performance gains of the CCRS.

An evolution toward cognitive cellular systems: licensed shared access for network optimization

This article reviews the application of the recent European Licensed Shared Access (LSA) concept for spectrum sharing between a mobile network operator (MNO) and an incumbent user. LSA, as a new area of application of cognitive technology, provides the MNO an opportunity to access new frequency resources on a shared basis. The article presents critical design criteria of LSA from the MNO point of view in order to allow future cognitive cellular networks to efficiently exploit shared spectrum bands. We describe the role of LSA bands in the context of heterogeneous networking, and identify the Long Term Evolution (LTE) and LTE-Advanced enabling technologies that support the introduction of LSA. Such technologies include traffic steering, carrier aggregation, and self-organizing networking. Additionally, we introduce an LSA management unit controlled by the MNO, to be implemented on top of the existing LTE/LTEAdvanced architecture, and we discuss the functionalities required for the optimization and automation of LSA resource management. We also depict the interrelations of the tasks between the LSA management unit and the supporting LTE/LTE-Advanced technologies. Based on the findings in this article, the ongoing cellular system evolution is shown to form a solid base for the introduction of new shared spectrum bands for cognitive cellular systems.

Fairness Guaranteed Cooperative Resource Allocation in Femtocell Networks

User-deployed low-power femtocell access points (FAPs) can provide better indoor coverage and higher data rates than conventional cellular networks. However, a major problem in this uncoordinated frequency reuse scenario is the inter-cell interference. In this paper, we propose a graph based distributed algorithm called fairness guaranteed cooperative resource allocation (FGCRA) to manage interference among femtocells. Since the optimal resource allocation is a NP-hard problem, which is difficult to get global optimization in femtocell networks, our proposed FGCRA algorithm provides sub-optimal resource allocation via cooperation among interfering neighbors. First, we propose a specific fairness factor obtained from two-hop interference relations, to determine the lower bound amount of subchannels that each FAP can use and guarantee the fairness among femtocells. Second, we propose scalable rules for distributed resource allocation and the solution to avoid the conflicts among interfering neighbors. Simulation results show that our proposed FGCRA significantly enhances both average user throughput and cell edge user throughput, and provides better fairness.

Performance evaluation of adaptive beamforming in 5G-V2X networks

Vehicles are the third fastest growing connected device type after smart phones and tablets. Also, automotive industry is interested to get more vehicles connected to the internet to improve traffic safety and efficiency. This creates a need for Vehicle-to-Everything (V2X) communications. In this work, the possibility of exploiting beamforming in LTE-V2X is considered. Singular value decomposition (SVD) receiver and precoder is implemented in an LTE-A system level simulator and the performance on multi-lane highway scenario is simulated and analyzed in downlink Vehicle-to-Infrastructure (V2I) scenario. The performance is compared to the conventional maximum-ratio combining (MRC) and LTE codebook precoded minimum mean square error (MMSE) receivers. In addition, the switched-beam beamforming is imitated by modified antenna patterns with 7 and 15 narrow beams. The results show that the SVD receiver provides gain compared to the conventional MRC and MMSE receivers in ideal scenario. Furthermore, with modified antenna patterns, the performance was enhanced when compared to the default antenna pattern.

Vehicle clustering for improving enhanced LTE-V2X network performance

Vehicle-to-Everything (V2X) communication holds the promise for improving road safety and reducing road accidents by enabling reliable and low latency services for vehicles. Vehicles are among the fastest growing type of connected devices. Therefore, there is a need for V2X communication, i.e., passing of information from Vehicle-to-Vehicle (V2V) or Vehicle-to-Infrastructure (V2I) and vice versa. In this paper, we focus on both V2I and V2V communication in a multi-lane freeway scenario, where coverage is provided by the Long Term Evolution Advanced (LTE-A) road side unit (RSU) network. Here, we propose a mechanism to offload vehicles with low signal-to-interference-plus-noise ratio (SINR) to be served by other vehicles, which have much higher quality link to the RSU. Furthermore, we analyze the improvements in the probabilities of achieving target throughputs and the performance is assessed through extensive system-level simulations. Results show that the proposed solution offloads low quality V2I links to stronger V2V links, and further increases successful transmission probability from 93% to 99.4%.

A channel allocation algorithm for Citizens Broadband Radio Service/Spectrum Access System

Recently, the Federal Communications Commission has proposed to create Citizens Broadband Radio Service (CBRS) with the three-tier spectrum sharing system to release more spectrum for the mobile broadband usage in the United States. At the moment, the Wireless Innovation Forum is involved in defining the operational and functional requirements for this framework based on [1], and also in standardizations. Evidently, the successful operation of this system depends on efficient channel allocation algorithms. In this paper, we consider the CBRS with the three-tier spectrum sharing system. A set of CBRS users, i.e., Priority Access License (PAL) and General Authorized Access (GAA) users are located in an area, which is divided into multiple census tracts. The PAL and GAA users request frequency channels from the spectrum access system (SAS). The role of the SAS is to allocate channels to these two types of users while providing interference protection to the incumbent users. For this setup, we consider the problem of channel allocation for PAL and GAA users. The objective is to allocate channels for these two types of users, while considering the channel allocation rules proposed in [1]. For this problem, we propose a channel allocation algorithm to be used by the SAS. The proposed algorithm allocates channels to the CBRS users in two steps: 1) allocate channels to the PAL users and 2) allocate channel to the GAA users. Numerically, we show that the proposed algorithm is able to allocate channels while satisfying the rules proposed in [1]. More importantly, this research provides new insights on investigating channel allocation algorithms in CBRS/SAS.

On The Effect of Channel-Aware Scheduling to CDMA Uplink Capacity

We show that channel-aware scheduling can significantly improve the capacity of CDMA uplink when compared to round robin scheduling. Using both analysis and simulations we quantify the capacity increase due to channel-aware scheduling in terms of reduction in intercell interference. The scheduling approaches can be used, e.g., within the current cdma2000 and WCDMA systems. Finally, we demonstrate that soft handover reduces the benefit from channel-aware scheduling and base station antenna gain properties are important for the scheduling performance

Co-primary Spectrum Sharing and Its Impact on MNOs’ Business Model Scalability

This paper focuses on inter-operator spectrum sharing, specifically co-primary spectrum sharing (CoPSS), that denotes the case where two or more MNOs (mobile network operators) operate in the same frequency band. Specifically, we discuss the concept and its impact on the mobile network operators’ (MNO) business model scalability potential. CoPSS has several technical and business advantages in volatile demand conditions. It highlights predefined policies and rules for sharing, utilization of subscriber and usage profiles for spectrum resource allocation, hybrid business models, value differentiation between exclusive and shared spectrum licenses, utilization of customer experience management systems (CEM) for value differentiation, and utilization of the LTE ecosystem.