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Algorithm Design for Low Latency Communication in Wireless Networks

ElAzzouni, Sherif
http://orcid.org/0000-0002-7728-6639
http://rave.ohiolink.edu/etdc/view?acc_num=osu1587049831134061

Abstract Details

2020, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
The new generation of wireless networks is expected to be a key enabler of a myriad of new industries and applications. Disruptive technologies such as autonomous driving, cloud gaming, smart healthcare, and virtual reality are expected to rely on a robust wireless infrastructure to support those applications' vast and diverse communication requirements. The successful realization of a large number of those applications hinges on timely information exchange, and thus, Latency arises as the critical requirement essential to unlock the true potential of the new 5G wireless generation. In order to ensure reliable low latency communication, new network algorithms and protocols prioritizing latency need to be developed across different layers of the network stack. Furthermore, a theoretical framework is needed to better understand the behavior of delay at the wireless edge and the proposed solutions' performance. In this dissertation, we study the problem of designing algorithms for low latency communication by addressing traditional problems such as resource allocation and scheduling from a delay-oriented standpoint, as well as, new problems that arise from the new 5G architecture such as caching and Heterogeneous Networks (HetNets) access. We start by a addressing the problem of designing real-time cellular downlink resource allocation algorithms for flows with hard deadlines. Attempting to solve this problem brings about the following two key challenges: (i) The flow arrival and the wireless channel state information are not known to the Base Station (BS) apriori, thus, the allocation decisions need to be made in an online manner. (ii) Resource allocation algorithms that attempt to maximize a reward in the wireless setting will likely be unfair, causing unacceptable service for some users. We model the problem of allocating resources to deadline-sensitive traffic as an online convex optimization problem. We address the question of whether we can efficiently solve that problem with low complexity. In particular, whether we can design a constant-competitive scheduling algorithm that is oblivious to requests' deadlines. To this end, we propose a primal-dual Deadline-Oblivious (DO) algorithm, and show it is approximately 3.6-competitive. We also explore the issues of fairness and long-term performance guarantees. We then address the potential of caching at wireless end-users where caches are typically very small, orders of magnitude smaller than the catalog size. We develop a predictive multicasting and caching scheme, where the BS in a wireless cell proactively multicasts popular content for end-users to cache, and access locally if requested. We analyze the impact of this joint multicasting and caching on delay performance and show that predictive caching fundamentally alters the asymptotic throughput-delay scaling. This practically translates to a several-fold delay improvement in simulations over the baseline at high network loads. We highlight a fundamental delay-memory trade-off in the system and identify the correct memory scaling to fully benefit from the network multicasting gains. We then shift our focus from centralized wireless networks to distributed wireless adhoc networks. We build on recent results in wireless networks that show that CSMA can be made throughput optimal by optimizing over activation rates at the cost of poor delay performance, especially for large networks. Motivated by those shortcomings, we propose a Node-Based version of the throughput optimal CSMA (NB-CSMA) as opposed to traditional link-based CSMA algorithms, where links were treated as separate entities. Our algorithm is fully distributed and corresponds to Glauber dynamics with “Block updates”. We show analytically and via simulations that NB-CSMA outperforms conventional link-based CSMA in terms of delay, highlighting that, exploiting the natural ``hotspots" in wireless networks can greatly improve delay performance. Finally, we shift our attention to the problem of Heterogeneous Networks (HetNets) access, where a cellular device can connect to multiple Radio Access Technologies (RATs) simultaneously including costly ubiquitous cellular technologies and other cheap intermittent technologies such as WiFi and mmWave. A natural question arises ``How should traffic be distributed over different interfaces, taking into account different application QoS requirements and the diverse nature of radio interfaces?". To this end, we propose the Discounted Rate Utility Maximization (DRUM) framework with interface costs as a means to quantify application preferences in terms of throughput, delay, and cost. We propose an online predictive algorithm that exploits the predictability of wireless connectivity for a small look-ahead window. We show that the proposed algorithm achieves a constant competitive ratio independent of the time horizon. Furthermore, the competitive ratio approaches 1 as the prediction window increases. We conduct experiments to better demonstrate the behavior of both delay-sensitive and delay-tolerant applications under intermittent connectivity. Our research demonstrates how low-complexity algorithms at the wireless edge could be designed to enable reliable low-latency communication and enables a deeper understanding of algorithm performance analysis from a delay standpoint.
Eylem Ekici (Advisor)
Ness Shroff (Advisor)
Atilla Eryilmaz (Committee Member)
190 p.
Electrical Engineering
Wireless Networks, Latency, Delay, Caching, Resource Allocation, Scheduling, Wireless Communication, Throughput Optimal, CSMA, Multicasting, Low-Latency Communication, Online Convex Optimization, Heavy Traffic

Recommended Citations

Citations

  • ElAzzouni, S. (2020). Algorithm Design for Low Latency Communication in Wireless Networks [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587049831134061

    APA Style (7th edition)

  • ElAzzouni, Sherif. Algorithm Design for Low Latency Communication in Wireless Networks. 2020. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1587049831134061.

    MLA Style (8th edition)

  • ElAzzouni, Sherif. "Algorithm Design for Low Latency Communication in Wireless Networks." Doctoral dissertation, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587049831134061

    Chicago Manual of Style (17th edition)

osu1587049831134061
410
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This open access ETD is published by The Ohio State University and OhioLINK.