Distributed Scheduling Protocol Research Articles

A Dynamic Distributed Multi-Channel TDMA Slot Management Protocol for Ad Hoc Networks

With the emergence of new technologies and standards for wireless communications and an increase in application and user requirements, the number and density of deployed wireless ad hoc networks is increasing. For deterministic ad hoc networks, Time-Division Multiple Access (TDMA) is a popular medium access scheme, with many distributed TDMA scheduling algorithms being proposed. However, with increasing traffic demands and the number of wireless devices, proposed protocols are facing scalability issues. Besides, these protocols are achieving suboptimal spatial spectrum reuse as a result of the unsolved exposed node problem. Due to a shortage of available spectrum, a shift from fixed spectrum allocation to more dynamic spectrum sharing is anticipated. For dynamic spectrum sharing, improved distributed scheduling protocols are needed to increase spectral efficiency and support the coexistence of multiple co-located networks. Hence, in this paper, we propose a dynamic distributed multi-channel TDMA (DDMC-TDMA) slot management protocol based on control messages exchanged between one-hop network neighbors and execution of slot allocation and removal procedures between sender and receiver nodes. DDMC-TDMA is a topology-agnostic slot management protocol suitable for large-scale and high-density ad hoc networks. The performance of DDMC-TDMA has been evaluated for various topologies and scenarios in the ns-3 simulator. Simulation results indicate that DDMC-TDMA offers near-optimal spectrum utilization by solving both hidden and exposed node problems. Moreover, it proves to be a highly scalable protocol, showing no performance degradation for large-scale and high-density networks and achieving coexistence with unknown wireless networks operating in the same wireless domain.

<italic>DeAMON</italic>: A Decentralized Adaptive Multi-Hop Scheduling Protocol for 6TiSCH Wireless Networks

The IEEE 802.15.4-2015 standard provides a link-layer mechanism, based on time synchronized channel hopping (TSCH), to enable deterministic low-power wireless mesh networking. The emerging IPv6 over IEEE 802.15.4e TSCH (6TiSCH) working group aims at harmonizing an IP-enabled protocol stack with the IEEE 802.15.4e link layer. In 802.15.4-TSCH medium access control, nodes follow a communication schedule; however, the standard does not specify any scheduling policy. Therefore, a number of recent studies have investigated scheduling mechanisms for 6TiSCH wireless networks. This paper introduces DeAMON , which is decentralized adaptive multi-hop scheduling protocol for 6TiSCH wireless networks. The key features of DeAMON include traffic-awareness, sequential scheduling, parallel transmissions, robust over-provisioning, and adaptability to topology changes. Moreover, DeAMON incurs minimal signaling overhead. Performance evaluation demonstrates that DeAMON outperforms state-of-the-art distributed scheduling protocols in terms of reliability, latency, and resource utilization.

Stochastic adaptive event‐triggered control and network scheduling protocol co‐design for distributed networked systems

In a distributed ‘networked control system’ (NCS), multiple physical systems or agents are connected to their corresponding controllers through a shared packet-switched communication network. For such distributed NCS, periodic sampled controller design is unsuitable to handle packet-switched closed-loop control systems and a novel stochastic optimal adaptive event-sampled controller scheme is proposed in the application layer for each physical system or agent expressed as an uncertain linear dynamic system. Lyapunov stability analysis will be utilised to derive the event trigger condition. In addition, a network scheduling protocol is also required for such NCS. Traditional network scheduling protocols are unsuitable for such NCS since the behaviour of the physical systems is disregarded during the protocol design. Therefore in this study, a novel distributed network scheduling protocol via cross-layer approach is developed to improve the performance of distributed NCS by minimising an overall system cost function which consists of the information collected from both the event-triggered controller for each physical system in the application layer and the distributed scheduling protocol from the network layer. It will be demonstrated that the proposed co-design approach will not only allocate the network resources efficiently but also it will improve the performance of the overall distributed NCS. Simulation results are included to demonstrate the effectiveness of the proposed cross-layer co-design.

On the Achievable Degrees-of-Freedom by Distributed Scheduling in (N,K)-User Interference Channels

We investigate achievable degrees-of-freedom (DoF) of an (N, K)-user interference channel where only K user (transmitter-receiver) pairs among N user pairs are allowed to simultaneously communicate in a dense network (N ≫ K). Each node is assumed to have M antennas and to be randomly located. We propose a distributed scheduling protocol to achieve the maximum DoF (i.e., MK), which sequentially and opportunistically selects a user pair causing/receiving interference lower than a pre-determined threshold to/from already selected user pairs in each step. It is proven that the proposed protocol achieves the maximum DoF, MK, in the (N, K)-user interference channel with less stringent network size N, compared with the conventional centralized protocol which has been known as the best. With zero-forcing detector at receiver, we prove that it is sufficient that the network size N scales at least as ω(SNR <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(M2)K(K-1))</sup> to achieve the maximum number of DoF MK, where SNR denotes the received signal-to-noise ratio. We also investigate the required feedback overheads of the proposed protocol and show that it is quite small when the network is strongly interference-limited because only a small number of users are required to transmit their signaling. Our numerical results show that our proposed scheme controls interference more effectively than the centralized protocol.

&lt;/title&gt; &lt;/titles&gt; &lt;publication_date&gt; &lt;month&gt;10&lt;/month&gt; &lt;year&gt;2010&lt;/year&gt; &lt;/publication_date&gt; &lt;pages&gt; &lt;first_page&gt;C1&lt;/first_page&gt; &lt;last_page&gt;C4&lt;/last_page&gt; &lt;/pages&gt; &lt;publisher_item&gt; &lt;item_number item_number_type='arNumber'&gt;5602239&lt;/item_number&gt; &lt;/publisher_item&gt; &lt;doi_data&gt; &lt;doi&gt;10.1109/TNET.2010.2086813&lt;/doi&gt; &lt;resource&gt;http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5602239&lt;/resource&gt; &lt;/doi_data&gt; &lt;/journal_article&gt; &lt;journal_article&gt; &lt;titles&gt; &lt;title&gt;&lt;![CDATA[Spectrum Sharing Between Wireless Networks

We consider the problem of two wireless networks operating on the same (presumably unlicensed) frequency band. Pairs within a given network cooperate to schedule transmissions, but between networks there is competition for spectrum. To make the problem tractable, we assume transmissions are scheduled according to a random access protocol where each network chooses an access probability for its users. A game between the two networks is defined. We characterize the Nash Equilibrium behavior of the system. Three regimes are identified: one in which both networks simultaneously schedule all transmissions, one in which the denser network schedules all transmissions and the sparser only schedules a fraction, and one in which both networks schedule only a fraction of their transmissions. The regime of operation depends on the path loss exponent α, the latter regime being desirable but attainable only for α > 4. This suggests that in certain environments, rival wireless networks may end up naturally cooperating. To substantiate our analytical results, we simulate a system where networks iteratively optimize their access probabilities in a greedy manner. We also discuss a distributed scheduling protocol that employs carrier sensing and demonstrate via simulations that again a near cooperative equilibrium exists for sufficiently large α.

A distributed and energy-efficient framework for Neyman-Pearson detection of fluctuating signals in large-scale sensor networks

To address the challenges inherent to a problem of practical interest - of Neyman-Pearson detection of fluctuating radar signals using wireless sensor networks, we propose in this paper a distributed and energy-efficient framework. Such framework is scalable with respect to the network size, and is able to greatly reduce the dependence on the central fusion center. It assumes a clustering infrastructure, and addresses signal processing and communications related issues arising from different layers. This framework includes a distributed scheduling protocol and a distributed routing protocol, which enable sensor nodes to make their own decisions about information transmissions, without requiring the knowledge of the network global information. In this framework, energy efficiency manifests itself at different network layers in a distributed fashion, and a balance between the detection performance and the energy efficiency is also attained.

Cross-layer distributed joint power control and scheduling for delay-constrained applications over CDMA-based wireless ad-hoc networks

In this paper, we propose a cross-layer distributed power control and scheduling protocol for delay-constrained applications over mobile CDMA-based ad hoc wireless networks. Herein, we propose a novel scheme where power control is employed to combat delay occurring on multi-hop wireless ad hoc networks via cross-layer information exchange. Based on that, a distributed power control and scheduling protocol is proposed to control the incurred delay as well as the multiple access interference (MAI). Unlike other previous work on power control and scheduling, we also investigate the impact of Doppler spread upon the system performance, and provide a robust system which employs a combination of power control, and coding/interleaving to combat the effects of Doppler spread by exploiting the time diversity when the Doppler spread gets large. Hence, our proposed approach can function appropriately over a wide range of channel conditions.

QoS guarantee and provisioning for realtime digital video over mobile ad hoc cdma networks with cross-layer design

In this article we investigate the trade-offs and the constraints for multimedia over mobile ad hoc CDMA networks, and propose a cross-layer distributed power control and scheduling protocol to resolve those trade-offs and constraints in order to provide high-quality video over wireless ad hoc CDMA networks. In particular, a distributed power control and scheduling protocol is proposed to control the incurred delay of video streaming over multihop wireless ad hoc networks, as well as the multiple access interference (MAI). We also investigate the impacts of Doppler spread and noisy channel estimates upon the end-to-end video quality, and provide a relatively robust system which employs a combination of power control and coding/interleaving to combat the effects of Doppler spread by exploiting the increased time diversity when the Doppler spread becomes large. Thus, more robust end-to-end video quality can be achieved over a wide range of channel conditions

Source routing and scheduling in packet networks

We study routing and scheduling in packet-switched networks. We assume an adversary that controls the injection time, source, and destination for each packet injected. A set of paths for these packets is admissible if no link in the network is overloaded. We present the first on-line routing algorithm that finds a set of admissible paths whenever this is feasible. Our algorithm calculates a path for each packet as soon as it is injected at its source using a simple shortest path computation. The length of a link reflects its current congestion. We also show how our algorithm can be implemented under today's Internet routing paradigms.When the paths are known (either given by the adversary or computed as above), our goal is to schedule the packets along the given paths so that the packets experience small end-to-end delays. The best previous delay bounds for deterministic and distributed scheduling protocols were exponential in the path length. In this article, we present the first deterministic and distributed scheduling protocol that guarantees a polynomial end-to-end delay for every packet.Finally, we discuss the effects of combining routing with scheduling. We first show that some unstable scheduling protocols remain unstable no matter how the paths are chosen. However, the freedom to choose paths can make a difference. For example, we show that a ring with parallel links is stable for all greedy scheduling protocols if paths are chosen intelligently, whereas this is not the case if the adversary specifies the paths.

Performance of a distributed scheduling protocol for TWIN

This paper discusses a scheduling mechanism for a new network architecture (TWIN) that provides arbitrary capacity up to a wavelength to any source-destination pair as needed, without optical-to-electronic conversion. The network emulates ultra-fast switching in the passive network core through the use of ultra-fast wavelength tunable lasers at the network edge. This architecture is suitable for any end-to-end traffic load, from static or quasi-static load (Sonet), to highly dynamic (IP) load. The key enabler of this architecture is a scheduling mechanism that schedules transmissions for maximal throughput. We propose a distributed scheduling scheme that is randomized for highly dynamic load and can learn to adjust for quasi-static load. We derive analytical formulae for the performance of the proposed scheme when load is highly dynamic, show that it outperforms standard protocols (such as &lt;i&gt;aloha&lt;/i&gt;) and illustrate the effect of learning for quasi-static load through simulation.