Channel Hopping Scheme Research Articles

Optimal DoS Attack Scheduling for Cyber–Physical Systems With Channel Hopping Scheme

Optimal DoS Attack Scheduling for Cyber–Physical Systems With Channel Hopping Scheme

A Fair Channel Hopping Scheme for LoRa Networks with Multiple Single-Channel Gateways.

LoRa is one of the most prominent LPWAN technologies due to its suitable characteristics for supporting large-scale IoT networks, as it offers long-range communications at low power consumption. The latter is granted mainly because end-nodes transmit directly to the gateways and no energy is spent in multi-hop transmissions. LoRaWAN gateways can successfully receive simultaneous transmissions on multiple channels. However, such gateways can be costly when compared to simpler single-channel LoRa transceivers, and at the same time they are configured to operate with pure-ALOHA, the well-known and fragile channel access scheme used in LoRaWAN. This work presents a fair, control-based channel hopping-based medium access scheme for LoRa networks with multiple single-channel gateways. Compared with the pure-ALOHA used in LoRaWAN, the protocol proposed here achieves higher goodput and fairness levels because each device can choose its most appropriate channel to transmit at a higher rate and spending less energy. Several simulation results considering different network densities and different numbers of single-channel LoRa gateways show that our proposal is able to achieve a packet delivery ratio (PDR) of around 18% for a network size of 2000 end-nodes and one gateway, and a PDR of almost 50% when four LoRa gateways are considered, compared to 2% and 6%, respectively, achieved by the pure-ALOHA approach.

Wi-Fi Direction Finding With Frequency-Scanned Antenna and Channel-Hopping Scheme

A novel and simple technique for Direction of Arrival (DoA) estimation in 802.11 Wi-Fi networks is proposed. It is based on the use of a dual-port frequency-beam scanning antenna, which is connected to single MIMO access point. By simply performing a channel hopping scheme and acquiring Received Signal Strength Information (RSSI) from each channel, the DoA can be estimated in a wide Field of View of 180° with a mean angular error of 5°. Due to its simplicity, a single commodity Wi-Fi AP can be used without the need of Channel State Information (CSI), or complex electronically reconfigurable or mechanically revolving antennas.

Energy-aware spectrum coordination with intelligent frequency-hopping for software defined networks

Software-defined Cognitive radio (CR) networking is considered a promising communication paradigm that can deliver huge spectrum opportunities for enabling massive deployment for wireless Internet-of-Things (IoT) applications and services. An important challenge in this domain is how to provide effective energy-efficient distributed spectrum coordination mechanisms (known as Spectrum Rendezvous), through which the CR IoT users can opportunistically coordinate their transmissions over the idle licensed frequency channels without relying on the existence of a dedicated common control channel (CCC). This paper proposes a novel frequency hopping (FH) distributed rendezvous mechanism for CR-capable IoT (CR-IoT) networks using grid-based quorum systems, referred to as adaptive grid-based quorum channel-hopping scheme. The proposed quorum-based scheme divides the time into equidistant cycle segments, referred to as quorum-based FH intervals. Each quorum interval consists of equal-duration beaconing intervals, each associated with a licensed channel. According to the proposed algorithm, each CR-IoT device randomly selects awake-sleep schedules based on the adopted quorum system structure. Any two devices can exchange their control information over the assigned channels of their common awake beaconing intervals. The proposed algorithm provides probabilistic guarantees on the successful rendezvous (RDV) between any two CR-IoT users within a single quorum-based FH interval (cycle) and dynamically adjusts the adopted QS structure based on the time-varying traffic load in the CR-IoT network such that the RDV probability and the expected average time to rendezvous improve with the least possible energy consumption. Compared to reference design schemes, the simulation results demonstrate that the proposed algorithm significantly increases the RDV probability, reduces the average rendezvous time, and reduces the energy consumption per successful RDV.

Channel Quality Prediction for TSCH Blacklisting in Highly Dynamic Networks: A Self-Supervised Deep Learning Approach

Cross-Technology Interference (CTI) is a severe issue for wireless networks operating in the license-free ISM bands. In particular, CTI can significantly affect the performance of low-power wireless links used in the Internet-of-Things (IoT). The IEEE 802.15.4 standard adopts a channel hopping scheme in its Time-Slotted Channel Hopping (TSCH) mode as a means to mitigating the adverse effect of CTI. However, the indiscriminate procedure by which TSCH nodes hop over different channels can suffer from severe interference in specific channels. Adaptive channel blacklisting is a technique to alleviate this issue by leaving out low-quality channels from the hopping list. To enable an effective blacklisting, especially in highly varying networks, an accurate real-time prediction of the quality of all available channels is of paramount importance. Previous studies rely on the past records of the channels as an indication of their quality in near future. Evidently, such approaches cannot extend to highly dynamic environments. This paper present a self-supervised approach for training deep neural networks capable of predicting the future behaviour of the frequency channels. The trained models can then substitute the quality assessment approaches in blacklisting schemas. Considering in-vehicle wireless networks as a target application, we evaluate this idea using a real-world experimental dataset, consisting of three measurement scenarios inside a moving vehicle. The experimental results show that using the proposed technique for TSCH blacklisting significantly improves the reliability of networks experiencing such highly dynamic interference and performs at least as good as the existing channel assessment methods in low-interference conditions.

Novel channel-hopping pattern-based wireless IoT networks in smart cities for reducing multi-access interference and jamming attacks

In smart cities, the Internet-of-Thing (IoT) provides an enabling communication infrastructure to support tremendous amount of data exchange. Most IoT applications, e.g., wireless local area network, Bluetooth and so forth, utilize the channel-hopping scheme to suppress the transmission security threats. In this paper, to reduce the mutual interference and external jamming attacks, multiple novel channel-hopping patterns, i.e., traditional no-hit-zone (NHZ) hopping pattern and generalized NHZ hopping pattern, are introduced to suit to IoT networks. Particularly the design of probabilistic hopping pattern is first proposed, which has the various usage probabilities with regard to various channels. The properties of these hopping patterns are investigated by the step-to-step examples. Then, the error-rate performance of the multi-node IoT systems adopting these hopping patterns in the presence of jamming attacks is comprehensively analyzed. The extensive simulations show that the traditional/generalized NHZ hopping patterns are in favor of combating the mutual interference but with the limited capability of reducing jamming attacks, while the probabilistic hopping pattern possesses the opposite feature, that is, it has the predominant merit in suppressing jamming attacks. Thus, the novel channel-hopping pattern-based IoT could provide the secure transmission for communication applications in smart cities. Note that, as the physical-layer security technique, the channel-hopping patterns investigated in this paper are convenient to integrate with the security policies implemented in upper layers (e.g., encryption, authentication and so forth).

A Latin rectangles-based TSCH scheduling and interference mitigation design

The Industrial Internet of Things (IIoT) connects a large number of industrial objects to the Internet that requires a higher level of control in terms of reliability, low power, and delay. IEEE 802.15.4e is the standard of the IIoT and includes time-synchronized channel hopping mechanisms to allow multiple communications. It controls the medium access operations using a time–frequency schedule. However, TSCH (Time Slotted Channel Hopping) specification does not specify how to build an optimized schedule. In this paper, we propose a distributed channel hopping scheme by providing an analytical model for the exploitation of Latin rectangles to avoid interference and collisions. Indeed, Latin rectangles are used to perform the scheduling process, where rows present the channel offsets and columns for slot offsets. Thus, the frequency of communication is derived using Latin rectangles, which prevents the scheduling function of nodes from considering channels already allocated in their neighborhood. Consequently, interference and multi-path fading are mitigated with more reliability and robustness. Markov chain model for the queue on every node is introduced and takes the bulk arrivals and the slot distribution into account. We analyze the efficiency of this algorithm by analytical techniques and extensive simulations for three bulk arrivals: Poisson, Bernoulli, and Geometric.

An Analysis on Optimal Attack Schedule Based on Channel Hopping Scheme in Cyber-Physical Systems.

In this paper, we investigate the issue of security on the remote state estimation in cyber-physical systems (CPSs), where a wireless sensor utilizes the channel hopping scheme to transmit the data to the remote estimator over multiple channels in the presence of periodic denial-of-service attacks. Assume that the jammer can interfere with a subset of channels at each attack time in active period. For an energy-constraint jammer, the problem of how to select the number of channels at each attack time to maximally deteriorate the CPS performance is investigated. Based on the index of average estimation error, we introduce two different attack strategies, which include selecting identical number of channels and unequal number of channels at each attack time, and further show theoretically that the attack effect by selecting unequal number of channels is better than that of selecting identical number of channels. By formulating the problem of selecting the number of channels as integer programming problems, we present the corresponding algorithm to approximate the optimal attack schedule for both cases. The numerical results are presented to validate the theoretical results and the effectiveness of the proposed algorithms.

Load-aware anti-jamming channel hopping design for cognitive radio networks

In cognitive radio networks (CRNs), access to unused portions of the licensed spectrum by secondary users renders the system vulnerable to malicious attack. A number of channel hopping schemes with anti-jamming capability have been proposed; however, existing solutions require the pre-sharing of access information or cannot guarantee rendezvous success. Furthermore, existing channel hopping schemes with anti-jamming capability do not consider variations in the traffic loads of different nodes. In this study, we developed a novel anti-jamming scheme, which allows for the dynamic adjustment of the sending/receiving ratio to maximize the throughput of an SU node. The proposed Load Awareness Anti-jamming channel hopping scheme is based on extended Langford pairing. The proposed scheme guarantees rendezvous for any pair of nodes, and was shown in simulations to outperform Sec-CH and Tri-CH in terms of throughput and TTR.

Channel-Hopping-Based Jamming Mitigation in Wireless LAN Considering Throughput and Fairness

Because of the popularity of wireless technology, jamming attack is one of the most critical issues in wireless networks. Wireless jamming attack is one type of denial-of-service attacks where attackers send malicious messages or signal on a legitimate channel by causing intentional interference in the network. In order to avoid jamming attacks, various jamming defense schemes have been proposed. One of the popular methods is a channel-hopping scheme. However, the main challenge of this method is generating a common channel number between the users and the access point without leaking that information to the jammer. We propose a new channel-hopping scheme where the access point shares a separate key with each user to isolate the damage on the network when a key has been compromised, while maintaining high throughput and fairness. We evaluate the proposed scheme through experiment on a test bed.

Synchronization and efficient channel hopping for power efficiency in LoRa networks: A comprehensive study

The usage of Low-Power Wide Area Networks (LPWAN) is increasing rapidly in many sectors of Internet of Things (IoT) applications. Long Range (LoRa) Wide Area Network (LoRaWAN) is a LPWAN, which has a long-range, low-cost and acts as a connectivity enabler. Most of the applications with real-time requirements, need reliable communication. This can be achieved by sharing a common time base across the network. However, making an efficient collaborative service of clock synchronization in LoRaWAN is challenging due to a lack of time notion. In this paper, We comprehensively study different approaches and design considerations for synchronization and tackle two problems of effective robustness in a LoRaWAN network. First, current research typically focuses on the benefits of LoRaWAN but ignores the requirement of reliability. To tackle this problem, we introduce a novel time synchronization scheme for radically reducing the usage of existing Aloha type protocol that handles energy consumption and service quality. Second, we look into the security space of LoRaWAN network, i.e. channel selection scheme for the given spectrum. Several security attacks are possible in LoRaWAN because the entire spectrum space is not used, and the utilization of few channels are comparatively higher. To tackle this problem, we present a channel hopping scheme that integrates cryptographic channel selection with the time notion. Finally, we evaluate the proposed time synchronization and channel hopping scheme for a real-world deployed peer to peer (P2P) model using commodity hardware. This paper concludes by suggesting the strategic research possibilities on top of this platform.

An Adaptive Channel Hopping and Dynamic Superframe Selection Scheme With QoS Considerations for Emergency Traffic Transmission in IEEE 802.15.6-Based Wireless Body Area Networks

In modern days, as medical technology advances and the world’s population grows, healthcare has been undergoing crucial changes. The common practice of clinical treatment is gradually being overhauled by ubiquitous healthcare systems. The wireless body area networks (WBANs) are becoming increasingly important for future healthcare applications. According to the human physiological information, WBAN not only sends the real-time notification to the user but also decreases the transmission delay of patient information to the physician for the medical decision. As medical emergency information must be transmitted after a disaster occurrence, the number of WBANs and emergency traffic increase in the particular area. In the situations, a large number of WBANs may be close to each other, thus causing inter-WBAN interference and increasing the transmission delay. Therefore, in this paper, we propose a dynamic channel and superframe selection scheme (DCSSS) in IEEE 802.15.6 WBANs. DCSSS records the channel interference degree which is used to adaptively select different superframe structures and to effectively transmit data. It mitigates the inter-WBAN interference to improve the transmission delay and QoS violation. Additionally, it increases the chance of successful data transmission before the deadline of the data as well as reduces power consumption.

Optimal Attack Strategy Against Wireless Networked Control Systems With Proactive Channel Hopping

This article investigates the security issue based on the proactive channel hopping scheme in wireless networked control systems (WNCS), where the sensor sends the measurement data to the controller through multiple channels attacked by a periodic denial-of-service jammer. For a jammer with the limited energy, the number of attacks, which denotes the amount of time expended in launching the attack, increases with the decline in the channel number attacked at each time, which has an effect on the success of receiving the data. On the basis of this, the problem of making an optimal tradeoff between the channel number attacked at each time and the attack number to degrade the WNCS performance maximally is investigated. We formulate this problem as an integer programming problem based on the linear quadratic Gaussian control cost function. Then, a necessary condition of the optimal solution without integrality constraints for this optimization problem is given for the scenario where the sensor utilizes one channel at each time to perform the data transmission. We further investigate this problem for the case where the sensor can select several channels at each time to transmit the measurement data. Moreover, for both cases the corresponding algorithms are presented to approximate optimal schedules. Finally, the theoretical results and the validity of the algorithm proposed are verified via the numerical results.

Difference-Set-Based Channel Hopping for Minimum-Delay Blind Rendezvous in Multi-Radio Cognitive Radio Networks

Rendezvous in the blind fashion is known as one of the most robust and effective ways for cognitive users (CUs) to exchange control information under the dynamic interference of primary users (PUs). Earlier, no existing scheme could guarantee CUs to rendezvous blindly in each timeslot, which makes them experience relatively long exchange delay. Based on the mathematical concept of relaxed cyclic difference set ( DS ), this paper proposes two novel channel hopping (CH) schemes for multi-radio CUs with and without a synchronized time clock to rendezvous blindly in every timeslot. This achievement of minimum rendezvous delay is especially useful for such delay-sensitive applications as real-time voice and emergency communications. Moreover, based on a special class of DS, the proposed two schemes can closely approach the theoretical lower bound on the number of radio transceivers for CUs to rendezvous blindly in every timeslot and, hence, minimizes their required hardware complexity to exchange control information at the minimum rendezvous delay. Numerical simulation shows that, under dynamic PU interference, the proposed schemes outperform the existing ones in terms of the average throughput and delay of CUs.

Asynchronous Channel-Hopping Scheme under Jamming Attacks

Cognitive radio networks (CRNs) are considered an attractive technology to mitigate inefficiency in the usage of licensed spectrum. CRNs allow the secondary users (SUs) to access the unused licensed spectrum and use a blind rendezvous process to establish communication links between SUs. In particular, quorum-based channel-hopping (CH) schemes have been studied recently to provide guaranteed blind rendezvous in decentralized CRNs without using global time synchronization. However, these schemes remain vulnerable to jamming attacks. In this paper, we first analyze the limitations of quorum-based rendezvous schemes called asynchronous channel hopping (ACH). Then, we introduce a novel sequence sensing jamming attack (SSJA) model in which a sophisticated jammer can dramatically reduce the rendezvous success rates of ACH schemes. In addition, we propose a fast and robust asynchronous rendezvous scheme (FRARS) that can significantly enhance robustness under jamming attacks. Our numerical results demonstrate that the performance of the proposed scheme vastly outperforms the ACH scheme when there are security concerns about a sequence sensing jammer.

Symmetric Channel Hopping for Blind Rendezvous in Cognitive Radio Networks Based on Union of Disjoint Difference Sets

In order to exchange control information without relying on any fixed control channel, neighboring cognitive users (CUs) in a multichannel cognitive radio network (CRN) can tune their transceivers to hop among a common set of spectrum channels and communicate when they rendezvous at a common channel in the blind fashion. Based on the combinatorial concept of the union of disjoint difference sets ( UDDS ), the present paper proposes two novel symmetric channel hopping (CH) schemes, namely UDDS-SCH and UDDS-ACH , for CUs with or without a synchronized time clock, respectively, to achieve blind rendezvous. By deriving their performance metrics, we then point out that both UDDS-SCH and -ACH can be optimized by adopting a special UDDS, which can be partitioned into mutually disjoint minimal difference sets ( MDSs ) as many as possible. This stimulates us to further develop exhaustive and heuristic solutions for searching the optimal and suboptimal numbers of mutually disjoint MDSs at high and low computational complexities, respectively. Based on these searching results, we finally show that both UDDS-SCH and -ACH can achieve better performance metrics than most existing symmetric CH schemes and remedy one major shortcoming of the best known ones, i.e., incapability to rendezvous at an arbitrary number of spectrum channels. Numerical simulation demonstrates that, when primary users may appear at part of or all rendezvous channels, the proposed CH schemes will outperform the existing ones in terms of the average transmission throughput and time of the CRN.

Anti-Jamming Rendezvous Scheme for Cognitive Radio Networks

In cognitive radio networks (CRNs), channel hopping-based communications are widely used to improve channel utilization. However, channel hopping schemes for CRNs are usually vulnerable to jamming attacks, especially when jammers have cognitive radios to perform channel sensing and fast channel switching. Many mitigating approaches for coping with jamming attacks in wireless communications rely on pre-shared secrets (e.g., pre-shared hopping sequences). In CRNs, pre-sharing secrets between senders and receivers is usually impractical (because neighborhood dynamically changes, and receivers of a broadcast may be unknown to the sender). Hence, anti-jamming channel hopping approaches without pre-shared secrets have gained more and more research interests. However, existing approaches either have unbounded time to rendezvous on an available channel (even no signals of jammers and PUs appear), or require role pre-assignment (SUs should be pre-assigned as a sender or receiver). Role pre-assignment is not applicable to environments where each SU may play a sender and a receiver, simultaneously. In this paper, we propose an anti-jamming channel hopping scheme, Sec-CH. Sec-CH has bounded time to rendezvous and can work without role pre-assignment.

Channel hopping scheme to mitigate jamming attacks in wireless LANs

Although a jamming attack is an important problem in Wi-Fi networks, there is no effective solution to this problem yet. In this paper, we propose a new approach to resolve jamming attacks in Wi-Fi networks based on the concept of channel hopping. If we assume that the attacker does not jam all the channels simultaneously, then it might be possible to circumvent a jamming attack by changing the channel. A channel hopping mechanism is designed so that the access point (AP) and a normal user can agree on the next channel with a high probability without pre-sharing of any secret information between the AP and a user node. The proposed scheme is evaluated through experiment in a test bed.

Combined Sector and Channel Hopping Schemes for Efficient Rendezvous in Directional Antenna Cognitive Radio Networks

Rendezvous is a prerequisite and important process for secondary users (SUs) to establish data communications in cognitive radio networks (CRNs). Recently, there has been a proliferation of different channel hopping- (CH-) based schemes that can provide rendezvous without relying on any predetermined common control channel. However, the existing CH schemes were designed with omnidirectional antennas which can degrade their rendezvous performance when applied in CRNs that are highly crowded with primary users (PUs). In such networks, the large number of PUs may lead to the inexistence of any common available channel between neighboring SUs which result in a failure of their rendezvous process. In this paper, we consider the utilization of directional antennas in CRNs for tackling the issue. Firstly, we propose two coprimality-based sector hopping (SH) schemes that can provide efficient pairwise sector rendezvous in directional antenna CRNs (DIR-CRNs). Then, we propose an efficient CH scheme that can be combined within the SH schemes for providing a simultaneous sector and channel rendezvous. The guaranteed rendezvous of our schemes are proven by deriving the theoretical upper bounds of their rendezvous delay metrics. Furthermore, extensive simulation comparisons with other related rendezvous schemes are conducted to illustrate the significant outperformance of our schemes.

The Effect of Increasing the Number of Transceivers in an Anti-jamming Channel-Hopping Scheme

The Effect of Increasing the Number of Transceivers in an Anti-jamming Channel-Hopping Scheme