scholarly journals Intra-Network Interference Robustness: An Empirical Evaluation of IEEE 802.15.4-2015 SUN-OFDM

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1691
Author(s):  
Robbe Elsas ◽  
Jeroen Hoebeke ◽  
Dries Van Leemput ◽  
Adnan Shahid ◽  
Glenn Daneels ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Ieee 802.15.4 ◽  
Empirical Evaluation ◽  
Medium Access ◽  
Frequency Space ◽  
Time Frequency ◽  
Channel Hopping ◽  
Access Mode ◽  
Utility Network ◽  
Modulation Diversity

While IEEE 802.15.4 and its Time Slotted Channel Hopping (TSCH) medium access mode were developed as a wireless substitute for reliable process monitoring in industrial environments, most deployments use a single/static physical layer (PHY) configuration. Instead of limiting all links to the throughput and reliability of a single Modulation and Coding Scheme (MCS), you can dynamically re-configure the PHY of link endpoints according to the context. However, such modulation diversity causes links to coincide in time/frequency space, resulting in poor reliability if left unchecked. Nonetheless, to some level, intentional spatial overlap improves resource efficiency while partially preserving the benefits of modulation diversity. Hence, we measured the mutual interference robustness of certain Smart Utility Network (SUN) Orthogonal Frequency Division Multiplexing (OFDM) configurations, as a first step towards combining spatial re-use and modulation diversity. This paper discusses the packet reception performance of those PHY configurations in terms of Signal to Interference Ratio (SIR) and time-overlap percentage between interference and targeted parts of useful transmissions. In summary, we found SUN-OFDM O3 MCS1 and O4 MCS2 performed best. Consequently, one should consider them when developing TSCH scheduling mechanisms in the search for resource efficient ubiquitous connectivity through modulation diversity and spatial re-use.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo
Keyword(s):  
Time Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
High Mobility ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Frequency Space ◽  
Time Frequency ◽  
Single Carrier ◽  
The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

scholarly journals Collision-Free Advertisement Scheduling for IEEE 802.15.4-TSCH Networks

Sensors ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 1789 ◽  
Author(s):  
Apostolos Karalis ◽  
Dimitrios Zorbas ◽  
Christos Douligeris
Keyword(s):  
Power Consumption ◽  
Ieee 802.15.4 ◽  
Mac Protocol ◽  
High Reliability ◽  
Mobile Nodes ◽  
Medium Access ◽  
Worst Case ◽  
Channel Hopping ◽  
Transmission Schedule ◽  
Scheduling Method

IEEE802.15.4-time slotted channel hopping (TSCH) is a medium access control (MAC) protocol designed to support wireless device networking, offering high reliability and low power consumption, two features that are desirable in the industrial internet of things (IIoT). The formation of an IEEE802.15.4-TSCH network relies on the periodic transmissions of network advertising frames called enhanced beacons (EB). The scheduling of EB transmissions plays a crucial role both in the joining time and in the power consumption of the nodes. The existence of collisions between EB is an important factor that negatively affects the performance. In the worst case, all the neighboring EB transmissions of a node may collide, a phenomenon which we call a full collision. Most of the EB scheduling methods that have been proposed in the literature are fully or partially based on randomness in order to create the EB transmission schedule. In this paper, we initially show that the randomness can lead to a considerable probability of collisions, and, especially, of full collisions. Subsequently, we propose a novel autonomous EB scheduling method that eliminates collisions using a simple technique that does not increase the power consumption. To the best of our knowledge, our proposed method is the first non-centralized EB scheduling method that fully eliminates collisions, and this is guaranteed even if there are mobile nodes. To evaluate our method, we compare our proposal with recent and state-of-the-art non-centralized network-advertisement scheduling methods. Our evaluation does not consider only fixed topology networks, but also networks with mobile nodes, a scenario which has not been examined before. The results of our simulations demonstrate the superiority of our method in terms of joining time and energy consumption.

scholarly journals Towards Improving TSCH Energy Efficiency: An Analytical Approach to a Practical Implementation

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6047
Author(s):  
Marcos A. Sordi ◽  
Ohara K. Rayel ◽  
Guilherme L. Moritz ◽  
João L. Rebelatto
Keyword(s):  
Energy Consumption ◽  
Ieee 802.15.4 ◽  
Practical Implementation ◽  
Mac Layer ◽  
Medium Access ◽  
Energy Consumption Model ◽  
Channel Hopping ◽  
Time Scheduling ◽  
Energy Constrained ◽  
Iot Devices

The IEEE 802.15.4-2015 standard defines a number of Medium Access Control (MAC) layer protocols for low power wireless communications, which are desirable for energy-constrained Internet of Things (IoT) devices. Originally defined in the IEEE 802.15.4e amendment, the Time Slotted Channel Hopping (TSCH) has recently been attracting attention from the research community due to its reduced contention (time scheduling) and robustness against fading (channel hopping). However, it requires a certain level of synchronization between the nodes, which can increase the energy consumption. In this work, we implement the Guard Beacon (GB) strategy, aiming at reducing the guard time usually implemented to compensate for imperfect synchronization. Moreover, besides presenting a realistic energy consumption model for a Contiki Operating System-based TSCH network, we show through analytical and practical results that, without the proposed scheme, the power consumption can be more than 13% higher.

scholarly journals TSCH Evaluation under Heterogeneous Mobile Scenarios

IoT ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 656-668
Author(s):  
Charalampos Orfanidis ◽  
Atis Elsts ◽  
Paul Pop ◽  
Xenofon Fafoutis
Keyword(s):  
Mobile Applications ◽  
Ieee 802.15.4 ◽  
Autonomous Robots ◽  
Industrial Applications ◽  
Mobility Patterns ◽  
Medium Access ◽  
Access Protocol ◽  
Channel Hopping ◽  
High Flexibility ◽  
Ieee 802.15.4 Standard

Time Slotted Channel Hopping (TSCH) is a medium access protocol defined in the IEEE 802.15.4 standard. It has proven to be one of the most reliable options when it comes to industrial applications. TSCH offers a degree of high flexibility and can be tailored to the requirements of specific applications. Several performance aspects of TSCH have been investigated so far, such as the energy consumption, reliability, scalability and many more. However, mobility in TSCH networks remains an aspect that has not been thoroughly explored. In this paper, we examine how TSCH performs under mobility situations. We define two mobile scenarios: one where autonomous agriculture vehicles move on a predefined trail, and a warehouse logistics scenario, where autonomous robots/vehicles and workers move randomly. We examine how different TSCH scheduling approaches perform on these mobility patterns and when a different number of nodes are operating. The results show that the current TSCH scheduling approaches are not able to handle mobile scenarios efficiently. Moreover, the results provide insights on how TSCH scheduling can be improved for mobile applications.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo ◽  
Yi Hong
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
Error Control ◽  
Estimation Method ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Receiver Design ◽  
Error Performance ◽  
Frequency Space ◽  
Time Frequency

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo ◽  
Yi Hong
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
Error Control ◽  
Estimation Method ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Receiver Design ◽  
Error Performance ◽  
Frequency Space ◽  
Time Frequency

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo
Keyword(s):  
Time Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
High Mobility ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Frequency Space ◽  
Time Frequency ◽  
Single Carrier ◽  
The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation: Analysis and Low-Complexity Receiver Design

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo ◽  
Yi Hong
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
Error Control ◽  
Estimation Method ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Receiver Design ◽  
Error Performance ◽  
Frequency Space ◽  
Time Frequency

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time-domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system.

scholarly journals Orthogonal Time Sequency Multiplexing Modulation

2021 ◽  
Author(s):  
Tharaj Thaj ◽  
Emanuele Viterbo
Keyword(s):  
Time Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
High Mobility ◽  
Low Complexity ◽  
Modulation Scheme ◽  
Frequency Space ◽  
Time Frequency ◽  
Single Carrier ◽  
The Time Domain

This paper proposes <i>orthogonal time sequency multiplexing</i> (OTSM), a novel single carrier modulation scheme based on the well known Walsh-Hadamard transform (WHT) combined with row-column interleaving, and zero padding (ZP) between blocks in the time-domain. The information symbols in OTSM are multiplexed in the delay and sequency domain using a cascade of time-division and Walsh-Hadamard (sequency) multiplexing. By using the WHT for transmission and reception, the modulation and demodulation steps do not require any complex multiplications. We then propose two low-complexity detectors: (i) a simpler non-iterative detector based on a single tap minimum mean square time-frequency domain equalizer and (ii) an iterative time-domain detector. We demonstrate, via numerical simulations, that the proposed modulation scheme offers high performance gains over orthogonal frequency division multiplexing (OFDM) and exhibits the same performance of orthogonal time frequency space (OTFS) modulation, but with lower complexity. In proposing OTSM, along with simple detection schemes, we offer the lowest complexity solution to achieving reliable communication in high mobility wireless channels, as compared to the available schemes published so far in the literature.

scholarly journals Fast Synchronization Scheme Using 2-Way Parallel Rendezvous in IEEE 802.15.4 TSCH

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1303 ◽  
Author(s):  
Byeong-Hwan Bae ◽  
Sang-Hwa Chung
Keyword(s):  
Ieee 802.15.4 ◽  
Network Synchronization ◽  
Medium Access ◽  
Transmission Strategy ◽  
Rendezvous Technique ◽  
Channel Hopping ◽  
Fast Network ◽  
Channel Information ◽  
High Level ◽  
Performance Results

The high level of robustness and reliability required in industrial environments can be achieved using time-slotted channel hopping (TSCH) medium access control (MAC) specified in institute of electrical and electronics engineers (IEEE) 802.15.4. Using frequency channel hopping in the existing TSCH network, a parallel rendezvous technique is used to exchange packets containing channel information before network synchronization, thereby facilitating fast network synchronization. In this study, we propose a distributed radio listening (DRL)–TSCH technique that uses a two-way transmission strategy based on the parallel rendezvous technique to divide the listening channel by sharing the channel information between nodes before synchronization. The performance evaluation was conducted using the OpenWSN stack, and the actual experiment was carried out by utilizing the OpenMote-cc2538 module. The time taken for synchronization and the number of rendezvous packets transmitted were measured in linear and mesh topologies, and the amount of energy used was evaluated. The performance results demonstrate a maximum average reduction in synchronization time of 67% and a reduction in energy consumption of 58% when compared to the performance results of other techniques.

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