Throughput and delay analysis of LWA with bursty traffic and randomized flow splitting

We investigate the effect of bursty traffic in a long term evolution (LTE) and Wi-Fi aggregation (LWA)-enabled network. The LTE base station routes packets of the same IP flow through the LTE and Wi-Fi links independently. We motivate the use of superposition coding at the LWA-mode Wi-Fi access point (AP) so that it can serve LWA users and Wi-Fi users simultaneously. A random access protocol is applied in such system, which allows the native-mode AP to access the channel with probabilities that depend on the queue size of the LWA-mode AP to avoid impeding the performance of the LWA-enabled network. We analyze the throughput of the native Wi-Fi network and the delay experienced by the LWA users, accounting for the native-mode AP access probability, the traffic flow splitting between LTE and Wi-Fi, and the operating mode of the LWA user with both LTE and Wi-Fi interfaces. Our results show some fundamental tradeoffs in the throughput and delay behavior of LWA-enabled networks, which provide meaningful insight into the operation of such aggregated systems

Design of LTE-Wi-Fi Aggregation with Multiple Wi-Fi APs for Heterogenous Network

The growth in mobile data traffic is forcing network operators to find ways to deliver higher bandwidth, better coverage, and better quality of service (QoS) at lower development costs. One method that can be used to meet this need is the aggregation technique. Aggregation techniques that run on several different technologies are called heterogeneous networks (HetNet). Recently, some advanced technologies have been proposed to aggregate different long-term evolution (LTE) carriers or different radio access technologies (RAT) to generate higher bandwidth. Many efforts have been made to improve the throughput of heterogeneous networks. One of the factors that affects the maximum LTE-WLAN aggregation (LWA) throughput is the Wi-Fi access point (AP) signal strength. Since the power of small cells is very low, the LWA range is not very large, so the LWA range needs to be increased. This paper proposes the solution that can be implemented by using multiple Wi-Fi Aps scheme. From the experiments, it found that LWA with multiple Wi-Fi APs has better signal strength than LWA with a single Wi-Fi AP. LWA with multiple Wi-Fi APs further increase the coverage of the network

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

D2.1 Performance evaluation framework

This deliverable contains a proposal for a performance evaluation framework that aims at ensuring that multiple projects within 5G-PPP wireless strand can quantitatively assess and compare the performance of different 5G RAN design concepts. The report collects the vision of several 5G-PPP projects and is conceived as a living document to be further elaborated along with the 5G-PPP framework workshops planned during 2016.Weber, A.; Agyapong, P.; Rosowski, T.; Zimmerman, G.; Fallgren, M.; Sharma, S.; Kousaridas, A.... (2016). D2.1 Performance evaluation framework. https://doi.org/10.13140/RG.2.2.35447.2192

Mobile Networks

The growth in the use of mobile networks has come mainly with the third generation systems and voice traffic. With the current third generation and the arrival of the 4G, the number of mobile users in the world will exceed the number of landlines users. Audio and video streaming have had a significant increase, parallel to the requirements of bandwidth and quality of service demanded by those applications. Mobile networks require that the applications and protocols that have worked successfully in fixed networks can be used with the same level of quality in mobile scenarios. Until the third generation of mobile networks, the need to ensure reliable handovers was still an important issue. On the eve of a new generation of access networks (4G) and increased connectivity between networks of different characteristics commonly called hybrid (satellite, ad-hoc, sensors, wired, WIMAX, LAN, etc.), it is necessary to transfer mechanisms of mobility to future generations of networks. In order to achieve this, it is essential to carry out a comprehensive evaluation of the performance of current protocols and the diverse topologies to suit the new mobility conditions

Performance Modeling and Analysis of Wireless Local Area Networks with Bursty Traffic

The explosive increase in the use of mobile digital devices has posed great challenges in the design and implementation of Wireless Local Area Networks (WLANs). Ever-increasing demands for high-speed and ubiquitous digital communication have made WLANs an essential feature of everyday life. With audio and video forming the highest percentage of traffic generated by multimedia applications, a huge demand is placed for high speed WLANs that provide high Quality-of-Service (QoS) and can satisfy end user’s needs at a relatively low cost. Providing video and audio contents to end users at a satisfactory level with various channel quality and current battery capacities requires thorough studies on the properties of such traffic. In this regard, Medium Access Control (MAC) protocol of the 802.11 standard plays a vital role in the management and coordination of shared channel access and data transmission. Therefore, this research focuses on developing new efficient analytical models that evaluate the performance of WLANs and the MAC protocol in the presence of bursty, correlated and heterogeneous multimedia traffic using Batch Markovian Arrival Process (BMAP). BMAP can model the correlation between different packet size distributions and traffic rates while accurately modelling aggregated traffic which often possesses negative statistical properties. The research starts with developing an accurate traffic generator using BMAP to capture the existing correlations in multimedia traffics. For validation, the developed traffic generator is used as an arrival process to a queueing model and is analyzed based on average queue length and mean waiting time. The performance of BMAP/M/1 queue is studied under various number of states and maximum batch sizes of BMAP. The results clearly indicate that any increase in the number of states of the underlying Markov Chain of BMAP or maximum batch size, lead to higher burstiness and correlation of the arrival process, prompting the speed of the queue towards saturation. The developed traffic generator is then used to model traffic sources in IEEE 802.11 WLANs, measuring important QoS metrics of throughput, end-to-end delay, frame loss probability and energy consumption. Performance comparisons are conducted on WLANs under the influence of multimedia traffics modelled as BMAP, Markov Modulated Poisson Process and Poisson Process. The results clearly indicate that bursty traffics generated by BMAP demote network performance faster than other traffic sources under moderate to high loads. The model is also used to study WLANs with unsaturated, heterogeneous and bursty traffic sources. The effects of traffic load and network size on the performance of WLANs are investigated to demonstrate the importance of burstiness and heterogeneity of traffic on accurate evaluation of MAC protocol in wireless multimedia networks. The results of the thesis highlight the importance of taking into account the true characteristics of multimedia traffics for accurate evaluation of the MAC protocol in the design and analysis of wireless multimedia networks and technologies

Design of medium access control techniques for cooperative wireless networks

Ph.DDOCTOR OF PHILOSOPH

Enabling Millimeter Wave Communication for 5G Cellular Networks: MAC-layer Perspective

Data traffic among mobile devices increases dramatically with emerging high-speed multimedia applications such as uncompressed video streaming. Many new applications beyond personal communications involve tens or even hundreds of billions wireless devices, such as wireless watch, e-health sensors, and wireless glass. The number of wireless devices and the data rates will continue to grow exponentially. Quantitative evidences forecast that total data rate by 2020 will be 1000 times of current 4G data rate. Next generation wireless networks need fundamental changes to satisfy the overwhelming capacity demands. Millimeter wave (mmWave) communication with huge available bandwidth is a very promising solution for next generation wireless networks to overcome the global bandwidth shortage at saturated microwave spectrum. The large available bandwidth can be directly translated into high capacity. mmWave communication has several propagation characteristics including strong pathloss, atmospheric and rain absorption, low diffraction around obstacles and penetration through objects. These propagation characteristics create challenges for next generation wireless networks to support various kinds of emerging applications with different QoS requirements. Our research focuses on how to effectively and efficiently exploit the large available mmWave bandwidth to achieve high capacity demand while overcoming these challenges on QoS provisioning for various kinds of applications. This thesis focuses on MAC protocol design and analysis for mmWave communication to provide required capacity and QoS to support various kinds of applications in next generation wireless networks. Specifically, from the transmitter/receiver perspective, multi-user beamforming based on codebook is conducted to determine best transmission/reception beams to increase network capacity considering the mutual interferences among concurrent links. From the channel perspective, both interfering and non-interfering concurrent links are scheduled to operate simultaneously to exploit spatial reuse and improve network capacity. Link outage problem resulting from the limited diffraction capability and low penetration capability of mmWave band is addressed for quality provisioning by enabling multi-hop transmission to replace the link in outage (for low-mobility scenarios) and buffer design with dynamic bandwidth allocation among all the users in the whole coverage area (for high-mobility scenarios). From the system perspective, system structure, network architecture, and candidate MAC are investigated and novel backoff mechanism for CSMA/CA is proposed to give more transmission opportunity to faraway nodes than nearby nodes in order to achieve better fairness and higher network capacity. In this thesis, we formulate each problem mentioned above as an optimization problem with the proposed algorithms to solve it. Extensive analytical and simulation results are provided to demonstrate the performance of the proposed algorithms in several aspects, such as network capacity, energy efficiency, link connectivity and so on