TCP Performance Analysis for LTE and LTE/WLAN Aggregation

Software Defined Radio (SDR) enables the execution of many hardware-based operations through software. With an open-source LTE software and an SDR, we are able to run a LTE base station on a PC or a portable and low-cost device. At the same time, simple devices such as Raspberry Pi can be turned into WiFi APs. In this work, we will work on the developed LTE/WiFi integration solution using OpenAirInterface software that implements the LTE eNB and the core network.Nowadays, mobile IP data traffic is increasing exponentially and predictions tells that it will triplicate its actual value in 2020. A solution to this dare is LTE/WLAN Aggregation technique where cellular networks such as LTE and WLAN networks such as WiFi are combined to improve its performance. In this thesis, a prototype, based on very tight coupling between LTE and WiFi, is evaluated for their performance. There will be three policies assessed: No Offload policy, when data traffic is sent over LTE link; Full Offload, when data packets is sent over WiFi link and control packets through LTE link; and LWA with different techniques to split traffic through both links: Time division, Par/Impar, Low ICMP RTT and Port division. In very tight coupling, eNB manages offloading and aggregation techniques, and does not require the core network in any case. PDCP layer, as common layer between both technologies, switches the traffic depending on the policy. Moreover, prioritizing reliability in front of throughput, an analysis of TCP flow control and default TCP congestion control method employed by Linux, namely CUBIC, theoretically and showing their functioning through physical experiments was performed

Implementation and evaluation of Open Source LTE-EPC Software

SDR, Software Defined Radio. In general, SDR is based on a common hardware platform to use software to implement various communication modules. There are two keywords in the concept, "universal hardware platform" and "software." The "universal hardware platform" means that we can implement a variety of communication functions based on this hardware platform, not that a hardware platform can only implement one kind of communication function. "Software" to implement the communication module is relative to the traditional radio technology. Since the SDR is more and more popular in the scientific research field, lots of different Open Source SDR Software can be used. In this thesis, I used two different open source LTE-EPC software to run the same setup in order to implement and evaluate the advantages and disadvantages of these softwares

Proportional Fair RAT Aggregation in HetNets

Heterogeneity in wireless network architectures (i.e., the coexistence of 3G, LTE, 5G, WiFi, etc.) has become a key component of current and future generation cellular networks. Simultaneous aggregation of each client's traffic across multiple such radio access technologies (RATs) / base stations (BSs) can significantly increase the system throughput, and has become an important feature of cellular standards on multi-RAT integration. Distributed algorithms that can realize the full potential of this aggregation are thus of great importance to operators. In this paper, we study the problem of resource allocation for multi-RAT traffic aggregation in HetNets (heterogeneous networks). Our goal is to ensure that the resources at each BS are allocated so that the aggregate throughput achieved by each client across its RATs satisfies a proportional fairness (PF) criterion. In particular, we provide a simple distributed algorithm for resource allocation at each BS that extends the PF allocation algorithm for a single BS. Despite its simplicity and lack of coordination across the BSs, we show that our algorithm converges to the desired PF solution and provide (tight) bounds on its convergence speed. We also study the characteristics of the optimal solution and use its properties to prove the optimality of our algorithm's outcomes.Comment: Extended version of the 31st International Teletraffic Congress (ITC 2019) conference pape

A Study of QoS in an Integrated Architecture of WLAN and Hetnet Based LTE-A

In this paper, an integration architecture based on loose coupling concept between WiFi and LTE heterogeneous networks (HetNet) was proposed. The ultimate objective is to investigate the feasibility and the practicality of the design through investigating the performance measures for different applications in the network. As well, a functionality of the load balancing was deployed in the architecture in order to prove that the architecture is flexible and can be opened to any further functionality. The architecture was built and simulated using riverbed network simulator. It was proved that the architecture is working appropriately, and the connectivity of the different technologies were demonstrated by applications communication with each other’s in the architecture. Along with, different existing load balancer algorithms were tested on the architecture and numerical results were obtained demonstrating that algorithm is better

Integration of Heterogeneous Networks: Protocols, Technologies, and Applications

Today, the possibility of being connected to the Internet at every time and without interruption is almost a reality. The great capabilities of new generation cellular networks and their wide coverage enable people to use the innumerable resources of the Internet, almost everywhere and in any mobility scenario. All modern mobile devices have multiple interfaces to get connected to the Internet, and (almost) all smartphone users think to know which interface is the best one to use in a specific situation. In particular, despite the great improvement of cellular networks, in certain situations, the use of an alternative network (for instance, WiFi, is to be preferred). Therefore, the selection of the best network is not straightforward. If we change perspective and we do not talk about people and their smartphones, rather about mobile machines (say vehicles) that have to stay connected in order to provide or to receive a certain service, then the matter of finding, at every time, the best network to connect to, appears a little more urgent. Furthermore, since in some situations it could be very important to have a performing connection, for example with very low delay, then it is evident that the selection of the best network is not trivial. The characteristics of the networks to use, in order to choose the best network, are different according to the application at hand. A world where machines move automatically and use the Internet just like humans seems at the moment far away, but it is rapidly approaching. Besides the problem of network selection, one could wonder why one should just use the best network, instead of using all networks available in order to get the best "sides" of all? The development of efficient methods for the integration of multiple networks is an interesting but still open research area. This thesis focuses on the interaction and integration of heterogeneous networks. Several innovative protocols, technologies, and applications developed, in order to make network integration easier for humans and automatic for machines, will be presented

On-demand offloading collaboration framework based on LTE network virtualisation

Recently, there has been a significant increase in data traffic on mobile networks, due to the growth in the numbers of users and the average data volume per user. In a context of traffic surge and reduced revenues, operators face the challenge of finding costless solutions to increase capacity and coverage. Such a solution should necessarily rule out any physical expansion, and mainly conceive real-time strategies to utilise the spectrum more efficiently, such as network offload and Long-term Evolution (LTE) network virtualisation. Virtualisation is playing a significant role in shaping the way of networking now and in future, since it is being devised as one of the available technologies heading towards the upcoming 5G mobile broadband. Now, the successful utilisation of such innovative techniques relies critically on an efficient call admission control (CAC) algorithm. In this work, framework is proposed to manage the operation of a system in which CAC, virtualisation and Local break out (LBO) strategies are collaboratively implemented to avoid congestion in a mobile network, while simultaneously guaranteeing that measures of quality of service (QoS) are kept above desired thresholds. In order to evaluate the proposed framework, two simulation stages were carried out. In the first stage, MATLAB was used to run a numerical example, with the purpose of verifying the mathematical model of the proposed framework in air interface level. The second stage involved of using open source applications such as, Emulated Virtual Environment (EVE) and Wireshark, for emulating the traffic in the network for different scenarios inside the core network. The results confirm the effectiveness of the proposed framework

Advanced Technologies Enabling Unlicensed Spectrum Utilization in Cellular Networks

As the rapid progress and pleasant experience of Internet-based services, there is an increasing demand for high data rate in wireless communications systems. Unlicensed spectrum utilization in Long Term Evolution (LTE) networks is a promising technique to meet the massive traffic demand. There are two effective methods to use unlicensed bands for delivering LTE traffic. One is offloading LTE traffic toWi-Fi. An alternative method is LTE-unlicensed (LTE-U), which aims to directly use LTE protocols and infrastructures over the unlicensed spectrum. It has also been pointed out that addressing the above two methods simultaneously could further improve the system performance. However, how to avoid severe performance degradation of the Wi-Fi network is a challenging issue of utilizing unlicensed spectrum in LTE networks. Specifically, first, the inter-system spectrum sharing, or, more specifically, the coexistence of LTE andWi-Fi in the same unlicensed spectrum is the major challenge of implementing LTE-U. Second, to use the LTE and Wi-Fi integration approach, mobile operators have to manage two disparate networks in licensed and unlicensed spectrum. Third, optimization for joint data offloading to Wi-Fi and LTE-U in multi- cell scenarios poses more challenges because inter-cell interference must be addressed. This thesis focuses on solving problems related to these challenges. First, the effect of bursty traffic in an LTE and Wi-Fi aggregation (LWA)-enabled network has been investigated. To enhance resource efficiency, the Wi-Fi access point (AP) is designed to operate in both the native mode and the LWA mode simultaneously. Specifically, the LWA-modeWi-Fi AP cooperates with the LTE base station (BS) to transmit bearers to the LWA user, which aggregates packets from both LTE and Wi-Fi. The native-mode Wi-Fi AP transmits Wi-Fi packets to those native Wi-Fi users that are not with LWA capability. This thesis proposes a priority-based Wi-Fi transmission scheme with congestion control and studied the throughput of the native Wi-Fi network, as well as the LWA user delay when the native Wi-Fi user is under heavy traffic conditions. The results provide fundamental insights in the throughput and delay behavior of the considered network. Second, the above work has been extended to larger topologies. A stochastic geometry model has been used to model and analyze the performance of an MPTCP Proxy-based LWA network with intra-tier and cross-tier dependence. Under the considered network model and the activation conditions of LWA-mode Wi-Fi, this thesis has obtained three approximations for the density of active LWA-mode Wi-Fi APs through different approaches. Tractable analysis is provided for the downlink (DL) performance evaluation of large-scale LWA networks. The impact of different parameters on the network performance have been analyzed, validating the significant gain of using LWA in terms of boosted data rate and improved spectrum reuse. Third, this thesis also takes a significant step of analyzing joint multi-cell LTE-U and Wi-Fi network, while taking into account different LTE-U and Wi-Fi inter-working schemes. In particular, two technologies enabling data offloading from LTE to Wi-Fi are considered, including LWA and Wi-Fi offloading in the context of the power gain-based user offloading scheme. The LTE cells in this work are subject to load-coupling due to inter-cell interference. New system frameworks for maximizing the demand scaling factor for all users in both Wi-Fi and multi-cell LTE networks have been proposed. The potential of networks is explored in achieving optimal capacity with arbitrary topologies, accounting for both resource limits and inter-cell interference. Theoretical analyses have been proposed for the proposed optimization problems, resulting in algorithms that achieve global optimality. Numerical results show the algorithms’ effectiveness and benefits of joint use of data offloading and the direct use of LTE over the unlicensed band. All the derived results in this thesis have been validated by Monte Carlo simulations in Matlab, and the conclusions observed from the results can provide guidelines for the future unlicensed spectrum utilization in LTE networks