Yasir Zaki

LTE wireless virtualization and spectrum management

Many research initiatives have started looking into Future Internet solutions in order to satisfy the ever increasing requirements on the Internet and also to cope with the challenges existing in the current one. Some are proposing further enhancements while others are proposing completely new approaches. Network Virtualization is one solution that is able to combine these approaches and therefore, could play a central role in the Future Internet. It will enable the existence of multiple virtual networks on a common infrastructure even with different network architectures. Network Virtualization means setting up a network composed of individual virtualized network components, such as nodes, links, and routers. Mobility will remain a major requirement, which means that also wireless resources need to be virtualized. In this paper the Long Term Evolution (LTE) was chosen as a case study to extend Network Virtualization into the wireless area.

LTE mobile network virtualization

Network virtualization is receiving immense attention in the research community all over the world. There is no doubt that it will play a significant role in shaping the way we do networking in the future. There have been different approaches to virtualize different aspects of the network: some are focusing on resource virtualization like node, server and router virtualization; while others are focusing on building a framework to set up virtual networks on the fly based on different virtual resources. Nevertheless, one very important piece of the puzzle is still missing, that is “Wireless Virtualization”. The virtualization of the wireless medium has not yet received the appropriate attention it is entitled to, and there have only been some early attempts in this field. In this paper a general framework for virtualizing the wireless medium is proposed and investigated. This framework focuses on virtualizing mobile communication systems so that multiple operators can share the same physical resources while being able to stay isolated from each other. We mainly focus on the Long Term Evolution (LTE) but the framework can also be generalized to fit any other wireless system. The goal of the paper is to exploit the advantages that can be obtained from virtualizing the LTE system, more specifically virtualizing the air interface (i.e. spectrum sharing). Two different possible gain areas are explored: spectrum multiplexing and multi-user diversity.

Influence of future M2M communication on the LTE system

Machine-to-Machine (M2M) communications is one of the latest research areas. This technology aims to enable machines to communicate with each other, mainly, without human intervention. M2M traffic is envisaged to play a big role within the coming years; lots of research projects and standardization bodies around the world have already started paying attention to the rising M2M communication. Current cellular mobile networks, such as LTE, are designed and optimized for traffic characteristics of human-based communication, but M2M traffic is different: Packet sizes are small, but transmitted periodically by numerous endpoints. In this paper, we focus on how LTE cellular networks will handle the massive deployment of M2M devices. In order to do so, the authors specified an M2M traffic model that represent a possible logistical scenario in the future. Besides M2M traffic, also regular LTE traffic is present in the network and the influence of the increasing M2M traffic is investigated. The results of the simulations show that M2M traffic will influence regular, human-based traffic. In particular the file upload time for regular LTE traffic experiences a considerable increase.

A Novel LTE Wireless Virtualization Framework

Network virtualization is one of the topics that recently have been receiving attention in the research community. It is becoming evidently clear that network virtualization will be a major player in the shaping of the Future Internet. Many research projects around the world are studying different aspects of network virtualization: some are focusing on resource virtualization like Node, Server and Router virtualization; while others are focusing on building a framework to setup virtual networks on the fly based on the different virtual resources. In spite of all that work, we still think that one very important piece of the puzzle is still missing that is “Wireless Virtualization”. According to the best of our knowledge, the virtualization of the wireless medium has not yet received the appropriate attention it is entitled to, and there has been very small work done in that field. This is why this paper is proposing a framework for the virtualization of the wireless medium. This framework is proposed to virtualize mobile communication systems so that multiple operators can share the same physical resources. We mainly focus on the Long Term Evolution (LTE) but the framework can also be generalized to fit any other wireless system.

Adaptive Congestion Control for Unpredictable Cellular Networks

Legacy congestion controls including TCP and its variants are known to perform poorly over cellular networks due to highly variable capacities over short time scales, self-inflicted packet delays, and packet losses unrelated to congestion. To cope with these challenges, we present Verus, an end-to-end congestion control protocol that uses delay measurements to react quickly to the capacity changes in cellular networks without explicitly attempting to predict the cellular channel dynamics. The key idea of Verus is to continuously learn a delay profile that captures the relationship between end-to-end packet delay and outstanding window size over short epochs and uses this relationship to increment or decrement the window size based on the observed short-term packet delay variations. While the delay-based control is primarily for congestion avoidance, Verus uses standard TCP features including multiplicative decrease upon packet loss and slow start. Through a combination of simulations, empirical evaluations using cellular network traces, and real-world evaluations against standard TCP flavors and state of the art protocols like Sprout, we show that Verus outperforms these protocols in cellular channels. In comparison to TCP Cubic, Verus achieves an order of magnitude (> 10x) reduction in delay over 3G and LTE networks while achieving comparable throughput (sometimes marginally higher). In comparison to Sprout, Verus achieves up to 30% higher throughput in rapidly changing cellular networks.

Investigation of Network Virtualization and Load Balancing Techniques in LTE Networks

Mobile Network Virtualization (NV) is an emerging technique which has drawn increasingly research attention. Network Virtualization enables multiple network operators to share a common infrastructure (including core network, transport network and access network) so as to reduce the investment capital while improving the overall performance at the same time. This is achieved by exploring the multiplexing gain. Similarly, Load Balancing (LB) is a well-known mechanism used in mobile networks to offload excessive traffic from high-load cells (hot spots) to low-load ones within one network operator. This paper aims at investigating the potential gain of applying NV in LTE (Long Term Evolution) networks and compares it with the LB scheme gain. In this paper, we propose an LTE virtualization framework (that enables spectrum sharing) and a dynamic load balancing scheme for multi-eNB and multi-VO (Virtual Operator) systems. We compare the performance gain of both schemes for different applications, e.g. VoIP, video, HTTP and FTP. We also investigate the parameterization of both schemes, e.g. sharing intervals, LB intervals and safety margins, in order to find the optimal parameter settings. The presented results show that the LTE networks can benefit from both NV and LB techniques.

Dissecting Web Latency in Ghana

Web access is prohibitively slow in many developing regions despite substantial effort to increase bandwidth and network penetration. In this paper, we explore the fundamental bottlenecks that cause poor web performance from a clients perspective by carefully dissecting webpage load latency contributors in Ghana. Based on our measurements from 2012 to 2014, we find several interesting issues that arise due to the increasing complexity of web pages and number of server redirections required to completely render the assets of a page. We observe that, rather than bandwidth, the primary bottleneck of web performance in Ghana is the lack of good DNS servers and caching infrastructure. The main bottlenecks are: (a) Recursive DNS query resolutions; (b) HTTP redirections; (c) TLS/SSL handshakes. We experiment with a range of well-known end-to-end latency optimizations and find that simple DNS caching, redirection caching, and the use of SPDY can all yield substantial improvements to user-perceived latency.

Performance evaluation of bandwidth and qos aware LTE uplink scheduler

A Long Term Evolution (LTE) eNodeB Medium Access Control (MAC) uplink scheduler is proposed in this paper for Single Carrier Frequency Division Multiple Access (SC-FDMA) as the uplink transmission scheme. Uplink scheduling algorithms available in literature commonly do not consider all the essential features of the LTE uplink. The proposed scheduler is shown to provide efficient allocation of radio resources to User Equipments (UEs) according to Quality of Service (QoS) of various traffic classes and the instantaneous channel conditions. The scheduler functionality is divided into Time Domain Packet Scheduling (TDPS) and Frequency Domain Packet Scheduling (FDPS). The proposed scheduler also supports multi-bearer UEs. The performance of the proposed scheduler is compared with common TDPS schedulers like Blind Equal Throughput (BET), Maximum Throughput (MT) and Proportional Fair (PF). The results show that the proposed scheduler guarantees provision of QoS to UEs and achieves an acceptable performance in terms of throughput.

Enhancing fairness and congestion control in multipath TCP

With the advancement in technology, today most of the end-host devices are equipped with multiple wired/wireless interfaces and capable of using them in parallel. This has led to research in taking advantage of utilizing additional available network resources simultaneously such as multiple paths between the multi-homed end devices to achieve better performance. In this regard, new multipath transport protocols such as Multipath TCP and Concurrent Multipath Transfer SCTP are being designed and developed. On one hand these new protocols need to optimize the usage of the available multiple paths efficiently with a suitable scheduler while on the other hand they should be also fair to the existing transport protocols like TCP and SCTP, especially in a congested environment. This paper illustrates and compares the solutions that have been proposed to ascertain that Multipath TCP can yield an improved performance while being fair to standard TCP. In addition, this paper highlights improvements to two of the proposed congestion control solutions-Dynamic Window Coupling and Opportunistic Linked Increases Algorithm. A brief look into hybrid scheduling mechanisms is also provided with a special interest in minimizing the overall reordering delay and to capture the dependency on the receiver buffer size. It is shown that the proposed solutions give good performance in most of the different bottleneck scenarios while staying friendly to legacy transport protocols.

Design and performance analysis of bandwidth and QoS aware LTE uplink scheduler in heterogeneous traffic environment

Long Term Evolution (LTE) uses Single Carrier Frequency Division Multiple Access (SC-FDMA) as the uplink transmission scheme. The Quality of Service (QoS) provision is one of the primary objectives of the wireless network operators. In this paper, the end-to-end QoS performance of Bandwidth and QoS Aware (BQA) scheduler for LTE uplink is evaluated in heterogeneous traffic environment. The BQA scheduler is designed to provide efficient allocation of radio resources to users according to the QoS requirements of various traffic classes and the instantaneous channel conditions. The user QoS provision is ensured by using dynamic QoS weights. Additionally, the delay sensitive traffic is facilitated by employing delay thresholds. The BQA scheduler algorithm supports multi-bearer users. The end-to-end QoS performance of the scheduler is analyzed in several simulation scenarios. The results show that the proposed scheduler guarantees provision of QoS to users.