Achieving Max-Min Throughput in LoRa Networks

With growing popularity, LoRa networks are pivotally enabling Long Range connectivity to low-cost and power-constrained user equipments (UEs). Due to its wide coverage area, a critical issue is to effectively allocate wireless resources to support potentially massive UEs in the cell while resolving the prominent near-far fairness problem for cell-edge UEs, which is challenging to address due to the lack of tractable analytical model for the LoRa network and its practical requirement for low-complexity and low-overhead design. To achieve massive connectivity with fairness, we investigate the problem of maximizing the minimum throughput of all UEs in the LoRa network, by jointly designing high-level policies of spreading factor (SF) allocation, power control, and duty cycle adjustment based only on average channel statistics and spatial UE distribution. By leveraging on the Poisson rain model along with tailored modifications to our considered LoRa network, we are able to account for channel fading, aggregate interference and accurate packet overlapping, and still obtain a tractable and yet accurate closed-form formula for the packet success probability and hence throughput. We further propose an iterative balancing (IB) method to allocate the SFs in the cell such that the overall max-min throughput can be achieved within the considered time period and cell area. Numerical results show that the proposed scheme with optimized design greatly alleviates the near-far fairness issue, and significantly improves the cell-edge throughput.Comment: 6 pages, 4 figures, published in Proc. International Conference on Computing, Networking and Communications (ICNC), 2020. This paper proposes stochastic-geometry based analytical framework for a single-cell LoRa network, with joint optimization to achieve max-min throughput for the users. Extended journal version for large-scale multi-cell LoRa network: arXiv:2008.0743

Enhancing LoRaWAN scalability with Longest First Slotted CSMA

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGCompelling features such as low power consumption and low complexity make LoRaWAN one of the most promising technologies to provide long-range connectivity to resource-constrained devices. However, LoRaWAN suffers from limited scalability since it uses an Aloha-based protocol for accessing the channel that causes a huge amount of frame collisions when the number of devices (or the network load) is high. This paper presents LFS-CSMA, a new medium access control mechanism that enhances the scalability of LoRaWAN networks by just combining the well-known slotted Aloha and CSMA schemes in a novel manner. With LFS-CSMA, longer frames are transmitted earlier within a given timeslot. Thus, devices with short frames to be transmitted can check the channel availability before sending them and avoid collisions if they detect an ongoing transmission. Performance results show that LFS-CSMA causes far less collisions than traditional MAC mechanisms, thus improving the scalability of LoRaWAN networks significantly.Agencia Estatal de Investigación | Ref. PID2020-113240RB-I00Xunta de Galici

Performance evaluation of LoRaWAN for Green Internet of Things

LoRa is a long-range, low power and single-hop wireless technology that has been envisioned for Internet of Things (IoT) applications having battery driven nodes. Nevertheless, increase in number of end devices and varying throughput requirements impair the performance of pure Aloha in LoRaWAN. Considering these limitations, we evaluate the performance of slotted Aloha in LoRaWAN using extensive simulations. We employed packet error rate (PER), throughput, delay, and energy consumption of devices under different payload sizes and varying number of end devices as benchmarks. Moreover, an analytical analysis of backlogged and non-backlogged under slotted Aloha LoRaWAN environment is also performed. The simulation shows promising results in terms of PER and throughput compared to the pure Aloha. However, increase in delay has been observed during experimental evaluation.Finally, we endorse slotted aloha LoRaWAN for Green IoT Environment

Performance Evaluation of LoRaWAN for Green Internet of Things

LoRa is a long-range, low power and single-hop wireless technology that has been envisioned for Internet of Things (IoT) applications having battery driven nodes. Nevertheless, increase in number of end devices and varying throughput requirements impair the performance of pure Aloha in LoRaWAN. Considering these limitations, we evaluate the performance of slotted Aloha in LoRaWAN using extensive simulations. We employed packet error rate (PER), throughput, delay, and energy consumption of devices under different payload sizes and varying number of end devices as benchmarks. Moreover, an analytical analysis of backlogged and non-backlogged under slotted Aloha LoRaWAN environment is also performed. The simulation shows promising results in terms of PER and throughput compared to the pure Aloha. However, increase in delay has been observed during experimental evaluation.Finally, we endorse slotted aloha LoRaWAN for Green IoT Environment

A Platform for Large-Scale Regional IoT Networks

The Internet of Things (IoT) promises to allow everyday objects to connect to the Internet and interact with users and other machines ubiquitously. Central to this vision is a pervasive wireless communication network connecting each end device. For individual IoT applications it is costly to deploy a dedicated network or connect to an existing cellular network, especially as these applications do not fully utilize the bandwidth provided by modern high speeds networks (e.g., WiFi, 4G LTE). On the other hand, decades of wireless research have produced numerous low-cost chip radios and effective networking stacks designed for short-range communication in the Industrial, Scientific and Medical Radio band (ISM band). In this thesis, we consider adapting this existing technology to construct shared regional low-powered networks using commercially available ISM band transceivers. To maximize network coverage, we focus on low-power wide-area wireless communication which enables links to reliably cover 10 km or more depending on terrain transmitting up to 1 Watt Equivalent Isotropically Radiated Power (EIRP). With potentially thousands of energy constrained IoT devices vying for extremely limited bandwidth, minimizing network coordination overhead and maximizing channel utility is essential. To address these challenges, we propose a distributed queueing (DQ) based MAC protocol, DQ-N. DQ-N exhibits excellent performance, supporting thousands of IoT devices from a single base station. In the future, these networks could accommodate a heterogeneous set of IoT applications, simplifying the IoT application development cycle, reducing total system cost, improving application reliability, and greatly enhancing the user experience

Collision Avoidance Resource Allocation for LoRaWAN

Data Availability Statement: The data presented in this study are available on request from the corresponding author.Funding: This research was partially funded by the Andalusian Knowledge Agency (project A-TIC- 241-UGR18), the Spanish Ministry of Economy and Competitiveness (project TEC2016-76795-C6-4-R) and the H2020 research and innovation project 5G-CLARITY (Grant No. 871428).The number of connected IoT devices is significantly increasing and it is expected to reach more than two dozens of billions of IoT connections in the coming years. Low Power Wide Area Networks (LPWAN) have become very relevant for this new paradigm due to features such as large coverage and low power consumption. One of the most appealing technologies among these networks is LoRaWAN. Although it may be considered as one of the most mature LPWAN platforms, there are still open gaps such as its capacity limitations. For this reason, this work proposes a collision avoidance resource allocation algorithm named the Collision Avoidance Resource Allocation (CARA) algorithm with the objective of significantly increase system capacity. CARA leverages the multichannel structure and the orthogonality of spreading factors in LoRaWAN networks to avoid collisions among devices. Simulation results show that, assuming ideal radio link conditions, our proposal outperforms in 95.2% the capacity of a standard LoRaWAN network and increases the capacity by almost 40% assuming a realistic propagation model. In addition, it has been verified that CARA devices can coexist with LoRaWAN traditional devices, thus allowing the simultaneous transmissions of both types of devices. Moreover, a proof-of-concept has been implemented using commercial equipment in order to check the feasibility and the correct operation of our solution.Andalusian Knowledge Agency A-TIC-241-UGR18Spanish Ministry of Economy and Competitiveness TEC2016-76795-C6-4-RH2020 research and innovation project 5G-CLARITY 87142

Goodbye, ALOHA!

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The vision of the Internet of Things (IoT) to interconnect and Internet-connect everyday people, objects, and machines poses new challenges in the design of wireless communication networks. The design of medium access control (MAC) protocols has been traditionally an intense area of research due to their high impact on the overall performance of wireless communications. The majority of research activities in this field deal with different variations of protocols somehow based on ALOHA, either with or without listen before talk, i.e., carrier sensing multiple access. These protocols operate well under low traffic loads and low number of simultaneous devices. However, they suffer from congestion as the traffic load and the number of devices increase. For this reason, unless revisited, the MAC layer can become a bottleneck for the success of the IoT. In this paper, we provide an overview of the existing MAC solutions for the IoT, describing current limitations and envisioned challenges for the near future. Motivated by those, we identify a family of simple algorithms based on distributed queueing (DQ), which can operate for an infinite number of devices generating any traffic load and pattern. A description of the DQ mechanism is provided and most relevant existing studies of DQ applied in different scenarios are described in this paper. In addition, we provide a novel performance evaluation of DQ when applied for the IoT. Finally, a description of the very first demo of DQ for its use in the IoT is also included in this paper.Peer ReviewedPostprint (author's final draft

A Survey on Long-Range Wide-Area Network Technology Optimizations

Long-Range Wide-Area Network (LoRaWAN) enables flexible long-range service communications with low power consumption which is suitable for many IoT applications. The densification of LoRaWAN, which is needed to meet a wide range of IoT networking requirements, poses further challenges. For instance, the deployment of gateways and IoT devices are widely deployed in urban areas, which leads to interference caused by concurrent transmissions on the same channel. In this context, it is crucial to understand aspects such as the coexistence of IoT devices and applications, resource allocation, Media Access Control (MAC) layer, network planning, and mobility support, that directly affect LoRaWAN’s performance.We present a systematic review of state-of-the-art works for LoRaWAN optimization solutions for IoT networking operations. We focus on five aspects that directly affect the performance of LoRaWAN. These specific aspects are directly associated with the challenges of densification of LoRaWAN. Based on the literature analysis, we present a taxonomy covering five aspects related to LoRaWAN optimizations for efficient IoT networks. Finally, we identify key research challenges and open issues in LoRaWAN optimizations for IoT networking operations that must be further studied in the future