For more than three decades, stochastic geometry has been used to model large-scale ad hoc wireless networks, and it has succeeded to develop tractable models to characterize and better understand the performance of these networks. Recently, stochastic geometry models have been shown to provide tractable yet accurate performance bounds for multi-tier and cognitive cellular wireless networks. Given the need for interference characterization in multi-tier cellular networks, stochastic geometry models provide high potential to simplify their modeling and provide insights into their design. Hence, a new research area dealing with the modeling and analysis of multi-tier and cognitive cellular wireless networks is increasingly attracting the attention of the research community. In this article, we present a comprehensive survey on the literature related to stochastic geometry models for single-tier as well as multi-tier and cognitive cellular wireless networks. A taxonomy based on the target network model, the point process used, and the performance evaluation technique is also presented. To conclude, we discuss the open research challenges and future research directions.

https://www3.nd.edu/~mhaenggi/pubs/tut13.pdf

Stochastic Geometry for Modeling, Analysis, and Design of Multi-Tier and Cognitive Cellular Wireless Networks: A Survey

An overview of vertical handover decision strategies in heterogeneous wireless networks

The fifth generation (5G) mobile networks are envisioned to support the deluge of data traffic with reduced energy consumption and improved quality of service (QoS) provision. To this end, key enabling technologies, such as heterogeneous networks (HetNets), massive multiple-input multiple-output (MIMO), and millimeter wave (mmWave) techniques, have been identified to bring 5G to fruition. Regardless of the technology adopted, a user association mechanism is needed to determine whether a user is associated with a particular base station (BS) before data transmission commences. User association plays a pivotal role in enhancing the load balancing, the spectrum efficiency, and the energy efficiency of networks. The emerging 5G networks introduce numerous challenges and opportunities for the design of sophisticated user association mechanisms. Hence, substantial research efforts are dedicated to the issues of user association in HetNets, massive MIMO networks, mmWave networks, and energy harvesting networks. We introduce a taxonomy as a framework for systematically studying the existing user association algorithms. Based on the proposed taxonomy, we then proceed to present an extensive overview of the state-of-the-art in user association algorithms conceived for HetNets, massive MIMO, mmWave, and energy harvesting networks. Finally, we summarize the challenges as well as opportunities of user association in 5G and provide design guidelines and potential solutions for sophisticated user association mechanisms.

/pdf/user-association-in-5g-networks-a-survey-and-an-outlook-4zdf9nh1ox.pdf

User Association in 5G Networks: A Survey and an Outlook

The architecture for the Beyond 3rd Generation (B3G) or 4th Generation (4G) wireless networks aims at integrating various heterogeneous wireless access networks. One of the major design issues is the support of vertical handoff. Vertical handoff occurs when a mobile terminal switches from one network to another (e.g., from wireless local area network to code-division multiple-access 1x radio transmission technology). The objective of this paper is to determine the conditions under which vertical handoff should be performed. The problem is formulated as a Markov decision process with the objective of maximizing the total expected reward per connection. The network resources that are utilized by the connection are captured by a link reward function. A signaling cost is used to model the signaling and processing load incurred on the network when vertical handoff is performed. The value iteration algorithm is used to compute a stationary deterministic policy. For performance evaluation, voice and data applications are considered. The numerical results show that our proposed scheme performs better than other vertical handoff decision algorithms, namely, simple additive weighting, the technique for order preference by similarity to ideal solution, and Grey relational analysis.

/pdf/an-mdp-based-vertical-handoff-decision-algorithm-for-1vowhpycah.pdf

An MDP-Based Vertical Handoff Decision Algorithm for Heterogeneous Wireless Networks

In heterogeneous wireless networks, an important task for mobile terminals is to select the best network for various communications at any time anywhere, usually called network selection. In recent years, this topic has been widely studied by using various mathematical theories. The employed theory decides the objective of optimization, complexity and performance, so it is a must to understand the potential mathematical theories and choose the appropriate one for obtaining the best result. Therefore, this paper systematically studies the most important mathematical theories used for modeling the network selection problem in the literature. With a carefully designed unified scenario, we compare the schemes of various mathematical theories and discuss the ways to benefit from combining multiple of them together. Furthermore, an integrated scheme using multiple attribute decision making as the core of the selection procedure is proposed.

/pdf/mathematical-modeling-for-network-selection-in-heterogeneous-5486qk0je0.pdf

Mathematical Modeling for Network Selection in Heterogeneous Wireless Networks — A Tutorial

In order to cater for the overwhelming growth in bandwidth demand from mobile Internet users operators have started to deploy different, overlapping radio access network technologies. One important challenge in such a heterogeneous wireless environment is to enable network selection mechanisms in order to keep the mobile users Always Best Connected (ABC) anywhere and anytime. Game theory techniques have been receiving growing attention in recent years as they can be adopted in order to model and understand competitive and cooperative scenarios between rational decision makers. This paper presents an overview of the network selection decision problem and challenges, a comprehensive classification of related game theoretic approaches and a discussion on the application of game theory to the network selection problem faced by the next generation of 4G wireless networks.

Game Theory-Based Network Selection: Solutions and Challenges

Development in wireless access technologies and multihomed personal user devices is driving the way towards a heterogeneous wireless access network environment. Success in this arena will be reliant on the ability to offer an enhanced user experience. Users will plan to take advantage of the competition and always connect to the network which can best service their preferences for the current application. They will rely on intelligent network selection decision strategies to aid them in their choice. The contribution of this paper is to propose an intelligent utility-based strategy for network selection in this multi-access network scenario. A number of utility functions are examined which explore different user attitudes to risk for money and delay preferences related to their current application. For example we show that risk takers who are willing to pay more money get a better service.

Utility-based Intelligent Network Selection in Beyond 3G Systems

Energy conservation has become a critical issue around the world. In smart phones, battery power capabilities are not keeping up with the advances in other technologies (e.g., processing and memory) and are rapidly becoming a concern, especially in view of the growth in usage of energy-hungry mobile multimedia streaming. The deficiency in battery power and the need for reduced energy consumption provides motivation for researchers to develop energy efficient techniques in order to manage the power consumption in next-generation wireless networks. As there is little analysis in the literature on the relationship between the wireless environment and the mobile device energy consumption, this paper investigates the impact of network-related factors (e.g., network load and signal quality level) on the power consumption of the mobile device in the context of video delivery. This paper analyzes the energy consumption of an Android device and the efficiency of the system in several scenarios while performing video delivery (over UDP or TCP) on an IEEE 802.11g network. The results show that the network load and the signal quality level have a combined significant impact on the energy consumption. This analysis can be further used when proposing energy efficient adaptive multimedia and handover mechanisms.

/pdf/energy-consumption-analysis-of-video-streaming-to-android-5divlsi6j5.pdf

Energy consumption analysis of video streaming to Android mobile devices

The continuing growth in video content exchanged by mobile users creates challenges for the network service providers in terms of supporting seamless multimedia delivery at high quality levels, especially given the existing wireless network resources. A solution that deals with this mobile broadband data growth is to make use of multiple networks supported by diverse radio access technologies. This multiaccess solution requires innovative network selection mechanisms to keep the mobile users always best connected anywhere and anytime. Additionally, there is a need to develop energy efficient techniques in order to reduce power consumption in next-generation wireless networks, while meeting user quality expectations. In this context, this paper proposes an enhanced power-friendly access network selection solution (E-PoFANS) for multimedia delivery over heterogeneous wireless networks. E-PoFANS enables the battery of the mobile device to last longer, while performing multimedia content delivery, and maintains an acceptable user perceived quality by selecting the network that offers the best energy-quality tradeoff. Based on real test-bed measurements, the proposed solution is modeled and validated through simulations. The results show how by using E-PoFANS, the users achieve up to 30% more energy savings with insignificant degradation in quality, in comparison with another state-of-the-art energy efficient network selection solution.

Enhanced Power-Friendly Access Network Selection Strategy for Multimedia Delivery Over Heterogeneous Wireless Networks

In future wireless and mobile environments it is likely that users will have access to multiple networks at the same time. Therefore there is a need to have mechanisms in place to decide which network is the most suitable for each user at each moment in time for every application that the user requires. We propose a user-centric solution where users choose the radio access network which meets their data transfer terms best. Naturally, each user wants timely quality data delivery at a low cost. In the radio environment data rates can never be guaranteed due to the unreliable nature of the radio links. The user network selection algorithm needs to predict the data rate on offer in each of the available networks and make the decision based on those predictions. This paper allows the user to select the network that will maximise the consumer surplus for non real-time data, while taking into account the delays

Olga Ormond

Papers

Game Theory-Based Network Selection: Solutions and Challenges

Utility-based Intelligent Network Selection in Beyond 3G Systems

Energy consumption analysis of video streaming to Android mobile devices

Enhanced Power-Friendly Access Network Selection Strategy for Multimedia Delivery Over Heterogeneous Wireless Networks

Network selection decision in wireless heterogeneous networks