Track 2 – MAC and Cross Layer Design

Session T2-S4

Resource Allocation

11:00 AM — 12:30 PM KST
May 26 Tue, 10:00 PM — 11:30 PM EDT

Effective Capacity based Resource Allocation for an Integrated Radar and Communications System

Yunfeng Liu, Zhiqing Wei and Zhiyong Feng (Beijing University of Posts and Telecommunications, China); Gordon Stüber (Georgia Institute of Technology, USA)

The integrated radar and communications system (IRCS) is promising for Unmanned Air Vehicles (UAVs). However, due to fast varying channels caused by high mobility, it is a tremendous challenge for the fusion center to collect detection information within the delay threshold. Based on only path loss of the channel, this paper performs power allocation to minimize the total transmit power while meeting the detection performance for radar and guaranteeing the latency violation probability (LVP) for communication. Using effective capacity theory, the latency constraint is expressed with introduced latency exponents. The resource allocation problem is non-convex and formulated to a convex one, which can be solved with a global optimum. Simulation results demonstrate the effectiveness of the proposed algorithm from the perspectives of the total transmit power and the latency of the communication links.

Traffic-Aware Beam Selection and Resource Allocation for 5G NR

Yu-Hsuan Liu and Kate Ching-Ju Lin (National Chiao Tung University, Taiwan)

3GPP has been defining 5G New Radio (NR), a new radio access technology, to enhance flexibility, scalability, and efficiency of 5G networks. An increasing data rate can be achieved by leveraging antenna arrays to adaptively form multiple directional beams and serve geo-distributed user equipments (UEs) concurrently. However, the imperfect beam pattern of an antenna array may create side lobes, leading to interuser interference. While most recent research focuses on beam selection that mitigates inter-user interference and maximizes the sum rate, we, however, notice that the selected beams may not be fully utilized. The root cause is that only a fixed set of beams can be configured at a time to serve a wide frequency band but some resource blocks (i.e., subcarriers) may not be able to be allocated to any UEs due to limited traffic demands. To address such inefficiency, this paper presents traffic-aware joint beam configuration and resource allocation, which explicitly considers UEs' traffic demands and configures beams that can be optimally utilized in all the RBs (i.e., the operational frequency band). Our simulation results show that our traffic-aware allocation configures beams with better utilization and achieve an effective throughput much higher than conventional maximal capacity configuration.

POET: An Energy-efficient Resource Management Mechanism for One-to-Many D2D Communications

Jun Huang (Chongqing University of Posts and Telecomm, China); Guohuan Wang (Chongqing Univ of Posts and Telecom & School of Commu. and Info. Eng., China); Cong-cong Xing (Nicholls State University, USA)

One-to-many Device-to-Device (D2D) communications, also refer to as D2D multicast communications, has been realized as an effective paradigm various practical settings. With the energy issue of mobile devices becomes more prominent, the energy efficiency of D2D multicast communication must be enhanced. In this paper, we propose POET, an energy-efficient resource management mechanism with joint Power cOntrol and channEl allocaTion for one-to-many D2D communications to address this issue. To be specific, by formulating the problem of energy efficiency maximization with QoS constraints on both cellular and D2D communications, we decompose this NP-hard problem into power control and channel allocation sub-problems. We present a gradient projection method for the first along with an iterative combinatorial auction algorithm for the second. Our preliminary results demonstrate that POET is lightweight and cost-effective in improving the energy efficiency of D2D multicast communications.

Cross-layer Resource Allocation in NOMA Systems with Dynamic Traffic Arrivals

Huiyi Ding (The University of Hong Kong, Hong Kong); Ka-Cheong Leung (Harbin Institute of Technology, Shenzhen, China)

Non-orthogonal multiple access (NOMA) has become a potential candidate to satisfy the heterogeneous demands in the fifth generation of wireless communication systems. With the optimization on the resource allocation, NOMA can further enhance the system performance. This paper proposes a cross-layer resource allocation framework for downlink NOMA systems. The problem is formulated as a stochastic problem to minimize the long-term total power consumption with dynamic traffic arrivals and time-varying channel under limited feedback. Then, this problem can be transformed to a rate control problem and a mixed-integer programming resource allocation problem solved at each time slot based on the Lyapunov optimization. To reduce the computational complexity, we devise an efficient suboptimal resource allocation algorithm with the dynamic penalty factor. The simulation results show that our proposed algorithms can reduce the power consumption compared with the two baseline algorithms while satisfying the QoS requirements.

Joint Power Allocation and Beam-forming Design for Dual-connectivity Wireless Networks

Minh Thang Nguyen, Jiho Song and Sungoh Kwon (University of Ulsan, Korea (South)); Kyung Sook Kim (ETRI, Korea (South))

In this paper, we propose a cooperating scheme to maximize network throughput while guaranteeing user quality of experience (QoE) demands in multiple-input-multiple-output (MIMO) systems. One of the aspired-to targets of the fifth generation (5G) network is to boost QoE everywhere, especially in the cell-edge areas. User equipments (UEs) in the edge areas are vulnerable to QoE violations, and they need dual connectivity from two nearby transmission points. Hence, UEs are categorized into two groups: single-connectivity and dual-connectivity. After classification, transmission power is allocated to maximize the network capacity while guaranteeing the minimum QoE. By comparing performance with a single connectivity-based algorithm and a fixed multi-connectivity-based algorithm, we show that our proposed algorithm not only satisfies all the UEs in the system but also maximizes the network capacity.

Session Chair

Bo Ji (Temple University, United States)

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Session T2-S5

Cross-Layer MAC Design

2:00 PM — 3:30 PM KST
May 27 Wed, 1:00 AM — 2:30 AM EDT

Simultaneous Transmit-Receive Multi-Channel Operation in Next Generation WLANs

Sharan Naribole, Wook Bong Lee, Srinivas Kandala and Ashok Ranganath (Samsung Semiconductor, Inc., USA)

The next-generation IEEE 802.11 standard project, IEEE 802.11be, is focused to meet the growing demands of applications including high throughput, low latency and high reliability. With the emergence of dual-radio end user devices (STAs) and tri-band Access Points (APs), efficient operation over multiple channels distributed over multiple bands is a key technology being discussed in IEEE 802.11be task group to achieve the desired objectives. Due to insufficient channel separation in frequency, STAs might be unable to perform simultaneous transmit and receive operations over the multiple channels in an asynchronous manner. To maximize the medium utilization of such constrained STAs participating in asynchronous multi-channel operation, we design and analyze Constraint Aware Asynchronous multi-channel operation (CA- ASYNC) protocol that includes an opportunistic 802.11 backoff resumption technique applied by the constrained STAs and multichannel busy state indication by the AP to the constrained STAs. Our results show that (a) CA-ASYNC's opportunistic backoff resumption technique significantly improves the medium utilization for constrained STAs compared to alternative strategies and (b) the multi-channel busy status indication significantly decreases the collisions due to constrained STAs and improves access delay performance.

A Differentially Private Classification Algorithm with High Utility for Wireless Body Area Networks

Xianwen Sun and Lingyun Shi (North China Electric Power University, China); Longfei Wu (Fayetteville State University, USA); Zhitao Guan (North China Electric Power University, China); Xiaojiang Du (Temple University, USA); Mohsen Guizani (Qatar University, Qatar)

The advancement of the wireless body area networks (WBAN) and sensor technologies allows us to collect a variety of physiological and behavioral data from human body. And appropriate application of machine learning methods can greatly promote the development of e-health. Nevertheless, the collected data contains personal privacy information. When using the machine learning methods to analyze the collected data, some information of the training data will be stored in the learning models unconsciously. To handle such information disclosure problem, we propose a differentially private classification algorithm based on ensemble decision tree with high utility for wireless body area networks. In order to improve the accuracy and stableness of classification, the bagging framework of ensemble learning is used in our algorithm. We aggregate the results of multiple private decision trees as the final classification in a weight-based voting way. For each private decision tree trained on the bootstrap samples, we offer a novel privacy budget allocation strategy that allows the nodes in larger depth to get more privacy budget, which can mitigate the problem of excessive noise introduced to leaf nodes to some extent. The better classification accuracy and stableness of this new algorithm, especially on small dataset, are demonstrated by simulation experiments.

Throughput Performance Study of Smart Antenna System in WiFi Networks

Hsin-Li Chiu, Sau-Hsuan Wu and Hsi-Lu Chao (National Chiao Tung University, Taiwan)

The throughput performance of smart antenna systems in WiFi networks is studied in this work. Considering a WiFi network whose access points (APs) support the switched-beam smart antenna system, a beam switching strategy which is compatible with the legacy WiFi protocol is proposed to enhance more concurrent links by allowing APs directionally sensing and accessing the wireless channel. The throughput advantage is verified by the simulation results in random deployment scenarios. More importantly, the proposed beam switching strategy provides extra design factors to adjust or balance the downlink and uplink throughput per WiFi user to meet the requirements of various applications and scenarios.

Resource Allocation and Throughput Maximization in Decoupled 5G Heterogeneous Networks

Humayun Zubair Khan (National University of Sciences and Technology & MCS CAMPUS, Pakistan); Mudassar Ali (University of Engineering and Technology Taxila, Pakistan); Muhammad Naeem (COMSATS University Islamabad, Wah Campus, Pakistan & Ryerson University, Canada); Imran Rashid (National University of Sciences and Technology, Pakistan); Adil Siddiqui (Military College of Signals, National University of Sciences and Technology, Pakistan); Muhammad Imran (National University of Sciences and Technology, Pakistan); Shahid Mumtaz (Instituto de Telecomunicações, Portugal)

Traditional downlink (DL)-uplink (UL) coupled cell association scheme is suboptimal solution for user association as most of the users are associated to a high powered macro base station (MBS) compared to low powered small base station (SBS) in heterogeneous network. This brings challenges like multiple interference issues, imbalanced user traffic load which leads to a degraded throughput in HetNet. In this paper, we investigate DL-UL decoupled cell association scheme to address these challenges and formulate a sum-rate maximization problem in terms of admission control, cell association and power allocation for MBS only, coupled and decoupled HetNet. The formulated optimization problem falls into a class of mixed integer non linear programming (MINLP) problem which is NP-hard and requires an exhaustive search to find the optimal solution. However, computational complexity of the exhaustive search increases exponentially with the increase in number of users. Therefore, an outer approximation algorithm (OAA), with less complexity, is proposed as a solution to find near optimal solution. Extensive simulations work have been done to evaluate proposed algorithm. Results show effectiveness of proposed novel decoupled cell association scheme over traditional coupled cell association scheme in terms of users associated/attached, mitigating interference, traffic offloading to address traffic imbalances and sum-rate maximization.

Cross-Layer Analysis of Distributed Passive RFID Systems Over Faded Backscattering Links

Roberto Valentini, Piergiuseppe Di Marco and Roberto Alesii (University of L'Aquila, Italy); Fortunato Santucci (University of l'Aquila, Italy)

In this paper, we propose a model for the analysis of distributed passive backscattering systems for Radio Frequency Identification with physically separated illuminator and reader. The model takes into account the physical channel characteristics including shadow fading components and thresholds for powering and detection. The dynamic framed ALOHA medium access mechanism defined by the EPC Global Generation 2 standard is considered to evaluate the performance. To address the complexity of the system model, our framework is based on a semi-analytical approach that combines moment matching approximation method at channel level and Monte-Carlo approach for the medium access control dynamics. Results show the impact of deployment conditions and the relative positions among illuminator, tags, and reader on the identification performance. Interestingly, the detection of the back-scattered signal at a remote reader can improve the performance with a higher probability of capture. However, as the distance increases, the impact of shadow fading counterpoises the capture effect. The resulting trade-off is accurately described by our model.

Session Chair

Kyung-Joon Park (DGIST, Korea)

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Session T2-S6

Wireless MAC for 5G

4:00 PM — 5:30 PM KST
May 27 Wed, 3:00 AM — 4:30 AM EDT

UAV-Assisted Data Collection with Non-Orthogonal Multiple Access

Weichao Chen, Shengjie Zhao and Rongqing Zhang (Tongji University, China); Liuqing Yang (Colorado State University, USA)

Unmanned aerial vehicles (UAVs) facilitate information collection greatly in Internet of Things (IoT) systems. On the other hand, non-orthogonal multiple access (NOMA) is regarded as a promising technology to provide high spectral efficiency and support massive connectivity in 5G networks. The integration of NOMA into UAV-assisted wireless networks shows great potential, but how to determine the user grouping and power allocation in NOMA according to the different locations of UAV is challenging. In this paper, we propose a general NOMA- enabled UAV-assisted data collection (NUDC) protocol to solve the formulated sum rate maximization problem such that the location of UAV, sensor grouping, and power control are jointly considered. Moreover, a joint signal-to-interference-ratio (SIR) hypergraph-based grouping and power control (SHG-PC) NOMA scheme is provided to obtain the appropriate sensor grouping and the optimal power control solutions efficiently. Extensive simulation results demonstrate the effectiveness of our proposed protocol.

HMC: A Hopping-based Multi-channel Coordination Scheme for URLLC in Unlicensed Spectrum

Hsueh-Yi Chen, Pei-Feng Lee and Te-Wei Chiang (National Central University, Taiwan); Sheng-Shih Wang (Lunghwa University of Science and Technology, Taiwan); Shiann-Tsong Sheu (National Central University, Taiwan)

IMT-2020 focuses on providing new services over diverse application scenarios, such as ultra-reliable low latency communications (URLLC). Regarding the increase of mobile traffic demand, the consensus of deploying 5G in unlicensed spectrum has been reached under the premise that the coexistence issue between 5G and Wi-Fi has been resolved. This paper proposes a hopping-based multi-channel coordination scheme, aiming at determining the minimal number of channels occupied for URLLC service without violating regulations. The proposed scheme uses the busy tone and full-duplex radio technologies to reduce the interference and collision. Moreover, by using the proposed scheme, the URLLC device can efficiently hop to the channel with less or no collision for data transmission. Numerical results validated that the proposed scheme actually achieves the reliability requirement of URLLC.

Graph-Based File Dispatching Protocol with D2D-Aided UAV-NOMA Communications in Large-Scale Networks

Baoji Wang (Peking University, China); Rongqing Zhang (Tongji University, China); Chen Chen and Xiang Cheng (Peking University, China); Liuqing Yang (Colorado State University, USA)

Unmanned aerial vehicle (UAV)-assisted communications are expected to become an important part of the next generation mobile communication systems, due to the high mobility of the UAVs. Non-orthogonal multiple access (NOMA) is regarded as a rosy technology in the fifth generation (5G) mobile communication systems, since it can effectively improve the spectral efficiency. In this paper, we combine the advantages of the UAV-assisted communications and NOMA, and propose a device-to-device (D2D)-enhanced UAV-NOMA network architecture, in which D2D is introduced to increase the file dispatching efficiency. Resource reuse based on spatial reuse is also allowed to further improve the spectral efficiency. Then, we propose a graph-based file dispatching (GFD) protocol to control the interference and minimize the UAV-assisted file dispatching mission time. Simulation results verify the advantages of our proposed D2D-enhanced UAV-NOMA network architecture and the efficiency of our designed GFD protocol.

MDP-based Resource Allocation for Uplink Grant-free Transmissions in 5G New Radio

Thilina Weerasinghe, Indika A. M. Balapuwaduge and Frank Y. Li (University of Agder, Norway); Vicente Casares-Giner (Universitat Politècnica de València, Spain)

The diversity of application scenarios in 5G mobile communication networks calls for innovative initial access schemes beyond traditional grant-based approaches. As a novel concept for facilitating small packet transmission and achieving ultra-low latency, grant-free communication is attracting lots of interests in the research community and standardization bodies. However, when a network consists of both grant based and grantfree based end devices, how to allocate slot resources properly between these two categories of devices remains as an unanswered question. In this paper, we propose a Markov decision process based scheme which dynamically allocates grant-free resources based on a specific reliability or priority requirement. The performance of the proposed scheme is evaluated via both analysis and simulations under various traffic arrival conditions.

Semi-Static Radio Frame Configuration for URLLC Deployments in 5G Macro TDD Networks

Ali Esswie (Nokia Bell Labs, Denmark); Klaus Pedersen (Nokia - Bell Labs, Denmark); Preben Mogensen (Nokia–Bell Labs, Research Center Aalborg, Sweden)

Dynamic time division duplexing (TDD) is one of the major novelties of the 5G new radio standard. It notably improves the network resource utilization with sporadic directional packet arrivals. Although, the feasibility of the ultra- reliable and low-latency communications (URLLC) within such deployments is critically challenged, mainly due to the cross-link interference (CLI). In this work, we propose a semi-static and computationally-efficient TDD radio frame adaptation algorithm for 5G macro deployments. Particularly, we first identify the quasi-static variance of the cross-cell traffic buffering performance, with various CLI co-existence conditions. Accordingly, a common radio frame pattern is dynamically estimated based on the filtered multi-cell traffic statistics. Our systemlevel simulation results show that the proposed solution achieves a highly improved URLLC outage performance, i.e., offering ~ 40% reduction gain of the achievable URLLC outage latency compared to perfect static-TDD, and approaching the optimal interference-free flexible-TDD case; though, with a significantly lower control overhead size.

Session Chair

Joohyun Lee (Hanyang University, Korea)

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