Inter-piconet Scheduling Research Articles

Relay Based Performance Metrics of Bluetooth Scatternet Scheduling

<p>Bluetooth is an emerging mobile ad-hoc network that accredits wireless communication to connect various short range devices. A single hop network called piconet is the basic communication topology of bluetooth which allows only eight active devices for communication among them seven are active slaves controlled by one master. Multiple piconets are interconnected through a common node, known as Relay, to form a massive network called as Scatternet. It is obvious that the performance of Scatternet scheduling is highly dependent and directly proportionate with the performance of the Relay node. In contrary, by reducing the number of Relays, it may lead to poor performance, since every Relay has to perform and support several piconet connections. The primary focus of this study is to observe the performance metrics that affects the inter-piconet scheduling since the Relay node’s role is like switch between multiple piconets. In this paper, we address and analyze the performance issues to be taken into consideration for efficient data flow in Scatternet based on Relay node.</p>

Internet Scheduling of Bluetooth Scatter Nets By Inter Piconet Scheduling

Internet Scheduling of Bluetooth Scatter Nets By Inter Piconet Scheduling

Internet Scheduling of Bluetooth Scatter Nets by Inter Piconet Scheduling

Internet Scheduling of Bluetooth Scatter Nets by Inter Piconet Scheduling

Dynamic relay management protocol for efficient inter-piconet scheduling in Bluetooth scatternet

Bluetooth is a low power, short range and inexpensive wireless technology that has limited resources. Therefore, the performance of a scatternet is highly dependent on the number of relays and their degree. The existence of unnecessary relays may increase scheduling overhead and consume system resources. In another instance, a large number of links that pass through a single relay may also decrease the system performance. Therefore, an optimum number of relays must be obtained for an efficient scatternet performance, while the system works with limited resources. The dynamic relay management (DRM) protocol is proposed to achieve the said objective and the solutions will be based on relay reduction and load balancing strategies. Through the DRM, a master reduces unnecessary relays to an optimum number and subsequently assigns them the special role as backup relays. In the event when a large number of links pass through a single relay, the master activates one of the backup relays to resolve the bottleneck, by which the load is balanced over a number of relays. Using this relay management technique, analytically the DRM protocol has reduced control overhead from O(n2) to O(1). Empirically, through simulation of the DRM protocol, the backup relay activation has reduced delay and improved throughput (between 40% and 60%). Also, the simulation results have demonstrated an improvement on network lifetime and packet loss. All these results are evidence that the DRM has outperformed the RVM and LORP protocols for the same issue. Hence, the inefficiency of the inter-piconet scheduling in a scatternet of a Bluetooth network can be resolved by implementing the DRM protocol.

Dynamic Congestion Control through backup relay in Bluetooth scatternet

Bluetooth is a low power wireless technology designed to connect various short-range devices such as laptops, cameras, cell-phones, head-phones, navigators, etc. Bluetooth has limited resources and its devices are connected in ad hoc fashion. The Bluetooth specification allows only eight active devices to communicate within its smallest networking unit known as piconet. Multiple piconets can be connected together through at least one common device, known as relay to form a bigger network called a scatternet. The performance of a scatternet is highly determined by the performance of the relay since it acts as a switch between multiple piconets, where inter-piconet scheduling is the main task to perform. However, the presence of too many relays in the network may cause inefficient use of the limited resources. In contrary, less number of relays may lead to congestion problem because each relay has to participate in multiple piconets and supports several connections. One possible solution is to reorganize the nodes in the scatternet, in order to increase the available bandwidth and to reduce the traffic flows on the congested link. Hence, primarily this paper addresses the issues of traffic congestion on a link by analyzing traffic load in the network. To achieve this, activation of a backup relay is performed by applying role-switching operation, and this technique is called Dynamic Congestion Control (DCC). With DCC, the route length is assured not to increase as to alleviate message and packet overheads in scheduling. The simulation results are evidence that DCC has reduced transmission delays and has increased the scatternet lifetime from 25% to 50% as compared to RVM and LORP techniques.

An efficient algorithm for scheduling in bluetooth piconets and scatternets

Bluetooth is a short-range radio technology operating in the unlicensed industrial-scientific-medical (ISM) band at 2.45 GHz. A piconet is basically a collection of slaves controlled by a master. A scatternet, on the other hand, is established by linking several piconets together in an ad hoc fashion to yield a global wireless ad hoc network. This paper proposes a scheduling policy that aims to achieve increased system throughput and reduced packet delays while providing reasonably good fairness among all traffic flows in bluetooth piconets and scatternets. We propose a novel algorithm for scheduling slots to slaves for both piconets and scatternets using multi-layered parameterized policies. Our scheduling scheme works with real data and obtains an optimal feedback policy within prescribed parameterized classes of these by using an efficient two-timescale simultaneous perturbation stochastic approximation (SPSA) algorithm. We show the convergence of our algorithm to an optimal multi-layered policy. We also propose novel polling schemes for intra- and inter-piconet scheduling that are seen to perform well. We present an extensive set of simulation results and performance comparisons with existing scheduling algorithms. Our results indicate that our proposed scheduling algorithm performs better overall on a wide range of experiments over the existing algorithms for both piconets (Das et al. in INFOCOM, pp. 591---600, 2001; Lapeyrie and Turletti in INFOCOM conference proceedings, San Francisco, US, 2003; Shreedhar and Varghese in SIGCOMM, pp. 231---242, 1995) and scatternets (Har-Shai et al. in OPNETWORK, 2002; Saha and Matsumot in AICT/ICIW, 2006; Tan and Guttag in The 27th annual IEEE conference on local computer networks(LCN). Tampa, 2002). Our studies also confirm that our proposed scheme achieves a high throughput and low packet delays with reasonable fairness among all the connections.

Ring of Masters (ROM): A new ring structure for Bluetooth scatternets with dynamic routing and adaptive scheduling schemes

This paper attempts to address the scatternet problem in Bluetooth through a comprehensive approach. We propose a new decentralized ring structure to combat the formation of traffic bottlenecks. The adopted construction protocol ensures flexibility of node selection and a good level of fault tolerance. The routing protocol combines both simplicity and robustness by taking advantage of the ring structure and relying on the collective memory of piconets to make forwarding and discarding decisions. The intra- and inter-piconet scheduling algorithm, called ROM adaptive scheduling (RAS), dynamically allocates time slots and is responsive to the varying workload conditions. We demonstrate, through analysis and simulations, that the various components of ROM yield a system that has good performance in terms of throughput, latency, delivery, and link utilization.

An Adaptive Interpiconet Scheduling Algorithm Based on HOLD Mode in Bluetooth Scatternets

To efficiently relay packets between associated piconets in an arbitrary-sized scatternet, an adaptive interpiconet scheduling algorithm is a requisite in a bridge. In this paper, we proposed a new interpiconet scheduling algorithm based on the HOLD mode - a power-saving mode of Bluetooth - to reduce the average interpiconet packet delay while increasing the utilization of a bridge. Generally speaking, interpiconet packet delay mainly results from the phenomenon that a bridge stays in one piconet without any interpiconet transmission activity in progress while other associated piconets are waiting for the bridge to deal with interpiconet packets. Thus, our proposed scheme estimates the time duration for which the bridge should stay in each piconet according to the traffic pattern so that the bridge can avoid being idle as possible. In particular, neither Bluetooth specification modifications nor any extra devices are needed to integrate our proposed interpiconet scheduling algorithm. Finally, the simulation results show the superiority of our proposed scheme, including low average delay, high throughput, and remarkable scalability.

On the Analysis of the Bluetooth Time Division Duplex Mechanism

Efficient communication in Bluetooth networks requires design of intra and inter-piconet scheduling algorithms, and therefore, numerous algorithms have been proposed. However, due to complexities of the Bluetooth MAC, the performance of these algorithms has been analyzed mostly via simulation. We present analytic results regarding the exhaustive, gated, and limited (pure round robin) scheduling algorithms in piconets with bidirectional and unidirectional traffic. We show that a piconet operated according to the limited scheduling algorithm is equivalent to a 1-limited polling system and present exact results regarding symmetric piconets with bidirectional traffic. Then, the difficulties in analyzing the performance of the exhaustive and gated algorithms in a piconet with bidirectional traffic are demonstrated. In addition, we present exact analytic results for piconets with unidirectional traffic. We show that, surprisingly, in symmetrical piconets with only uplink traffic, the mean waiting time is the same for the exhaustive and limited algorithms. This observation results from the differences between piconets and traditional polling systems and can be extended for time-division-duplex systems with arbitrary packet lengths. Furthermore, we show that the mean waiting time in a piconet with only uplink traffic is significantly higher than its corresponding value in a piconet with only downlink traffic. Finally, we numerically compare the exact results to approximate results, presented in the past.

A power-aware master and bridge scheduling scheme for bluetooth scatternets

We propose an intra-piconet and inter-piconet scheduling scheme for Bluetooth in which a master assigns priority to each slave based on its packet arrival rate, available buffer space and the number of messages stored in the master buffer for that slave. The number of times a particular slave is polled by its master in succession is dependent on the assigned priority. The slaves know the polling sequence in advance and go to a power-saving mode during the intervening time interval. For bridge scheduling, a bridge is assigned to each piconet for a quantum of time that is determined by the inter-piconet traffic. We compare performance of the proposed scheme with other existing methods by simulation studies.

A traffic-aware scheduling for bluetooth scatternets

Bluetooth is a low cost, low power, short-range radio technology used for wireless personal area networks (PANS). Bluetooth scatternet is a set of piconets interconnected via devices. Good interpiconet schedulings are necessary for devices to switch among piconets they participate in. This paper proposes an interpiconet scheduling algorithm named Traffic-Aware Scatternet Scheduling (TASS), for bridges in Bluetooth scatternets. According to masters' traffic information, TASS can adaptively switch the to high traffic load masters, and increase the usage of the bridge. In addition, TASS can reduce the number of failed unsniffs and the overhead of bridge switch wastes to further increase overall system performance. Simulation results show that TASS outperforms existing interpiconet scheduling in both network throughput and adaptability for various traffic loads.

A Credit-Based On-Demand QoS Routing Protocol Over Bluetooth WPANs

The quality-of-service (QoS) communication that supports mobile applications to guarantee bandwidth utilization is an important issue for Bluetooth wireless personal area networks (WPANs). In this paper, we address the problem of on-demand QoS routing with interpiconet scheduling in Bluetooth WPANs. A credit-based QoS (CQ) routing protocol is developed which considers different Bluetooth packet types, because different types of Bluetooth packets have different bandwidth utilization levels. This work improves the bandwidth utilization of Bluetooth scatternets by providing a new interpiconet scheduling scheme. This paper mainly proposes a centralized algorithm to improve the bandwidth utilization for the on-demand QoS routing protocol. The centralized algorithm incurs the scalability problem. To alleviate the scalability problem, a distributed algorithm is also investigated in this work. The performance analysis illustrates that our credit-based QoS routing protocol achieves enhanced performance compared to existing QoS routing protocols.

Adaptive interpiconet scheduling for multipurpose scatternet scenarios

Bluetooth specification still has open issues, including the intra and interpiconet scheduling topics. This article proposes an interpiconet scheduling algorithm, referred to as AISA (Adaptive Interpiconet Scheduling Algorithm). AISA is characterized by its adaptability to varying network traffic conditions; and its ability to optimize specific performance metrics via parameterization. Both features enable it to be employed in a variety of scenarios with improved performance shown by the simulation results.

Load-adaptive inter-piconet scheduling in small-scale Bluetooth scatternets

Bluetooth enables wireless communication via ad hoc networks. The basic topology (piconet) is a collection of slaves controlled by a master. A scatternet is a multihop network of piconets. We anticipate that most scatternets will be composed of only a few piconets. However, even in small scatternets, efficient data flow requires the design of inter-piconet scheduling algorithms. Thus, this article presents and evaluates a load adaptive scheduling algorithm tailored for small-scale scatternets. The main advantage of this algorithm is the use of the Bluetooth low-power hold mode, which allows greater flexibility than other low-power modes. A simulation model has been developed in order to evaluate the performance of the algorithm. We show that the results obtained by the model are very close to the analytic results. Then we evaluate the performance of various intra-piconet scheduling algorithms. Finally, we present simulation results regarding inter-piconet scheduling, and compare the proposed algorithm to algorithms using the sniff mode.

Bluetooth scatternet formation: A survey

This paper describes the issue of piconet interconnection for Bluetooth technology. These larger networks, known as scatternets, have the potential to increase networking flexibility and facilitate new applications. While the Bluetooth specification permits piconet interconnection, the creation, operation and maintenance of scatternets remains open. In this paper, the research contributions in this arena are brought together, to give an overview of the state-of-the-art. First, operation of the Bluetooth system is explained, followed by the mechanism for link formation. Then, the issue of piconet interconnection is considered in detail. Processes for network formation, routing and intra- and inter-piconet scheduling, are explained and classified. Finally, the research issues arising are outlined.

A fair and traffic dependent scheduling algorithm for Bluetooth scatternets

The Bluetooth specification defines the notion of interconnected piconets, called scatternets, but does not define the actual mechanisms and algorithms necessary to set up and maintain them. The operation of a scatternet requires some Bluetooth units to be interpiconet units (gateways), which need to time-division multiplex their presence among their piconets. This requires a scatternet-scheduling algorithm that can schedule the presence of these units in an efficient manner. In this paper, we propose a distributed scatternet-scheduling scheme that is implemented using the HOLD mode of Bluetooth and adapts to non-uniform and changing traffic. Another attribute of the scheme is that it results in fair allocation of bandwidth to each Bluetooth unit. This scheme provides an integrated solution for both intra-and inter-piconet scheduling, i.e., for polling of slaves and scheduling of gateways.

Adaptive inter-piconet scheduling in small scatternets

Inter-piconet scheduling in a Bluetooth scatternet may be performed in an adaptive manner, so as to minimize end-to-end packet delays. Using the theory of queues with vacations, we analyze the impact of different values of scatternet parameters on end-to-end delays, and then investigate the possibility of minimization of the aforementioned delays. We show that such minimization is possible for scatternets with both Slave/Slave and Master/Slave bridges, and that it should be based on inter-piconet traffic. We also describe simple algorithms that enable the scatternet to achieve near minimum delays in a wide range of traffic parameter values.

스니프 모드 기반의 효율적인 블루투스 스캐터넷 스케줄링 기법

블루투스 통신은 한 개의 마스터와 최대 7개의 슬레이브로 구성된 피코넷을 기본 단위로 이루어지며, 다수의 피코넷은 브리지 노드라 불리는 공유 노드를 통해 상호 연결되어 스캐터넷을 형성한다. 브릿지 노드는 스위칭을 통해 피코넷간 통신을 수행하며, 이때 스위칭은 슬롯의 낭비, 즉 패킷 지연 시간을 최소화 할 수 있도록 주의 깊게 스케줄링 되어야 한다. 본 논문에서는 스니프 모드에 기반 한 효율적인 인터 피코넷 스케줄링 기법을 제안한다 스케줄링 기법은 브릿지 노드가 슬레이브로 동작하는 각 피코넷에 대해 스니프 모드를 통해 할당된 통신 시간 중 낭비되는 슬롯을 자신이 마스터로 동작하는 피코넷 통신에 할당함으로써 슬롯의 낭비를 줄인다. 각 피코넷에 할당되는 통신 시간은 트래픽의 양에 따라 적응적으로 결정된다. 실험 결과에 의하면 통신 시간을 균등하게 할당하는 라운드-로빈 기법에 비해 좋은 결과를 보인다. Bluetooth communication is based on piconet, which is composed by one master and maximum seven slaves. Several piconets can be interconnected via an inter-piconet Bluetooth unit called a bridge unit to form a Bluetooth scatternet. This bridge node can make its presence in each piconet by switching. This switching must be carefully scheduled so that slot wastage and, hence, packet delays are minimized. In this paper, we introduce an efficient inter-piconet scheduling scheme based on sniff mode. This scheme tries to minimize the wastage of slots by having the bridge unit sniff with its peering masters with time limits and communicate with its slaves in remaining slots. The sniff time limits are determined adaptively based on the amount of traffic in each piconet. Simulation results show this scheme outperforms round-robin scheme based on sniff intervals of equal lengths.

Bluetooth: an enabler for personal area networking

We find ourselves today often carrying numerous portable electronic devices, such as notebook computers, mobile phones, PDAs, digital cameras, and mp3/MD/DVD players, used to help and entertain us in our professional as well as private lives. For the most part, these devices are used separately, and their applications do not interact. Imagine, however, if they could interact directly and thus create a network where information may flow seamlessly between the devices-such a network of personal devices is often referred to as a personal area network, or PAN. Moreover, access to the Internet via a (public) wireless LAN access point and/or via a 3G UMTS mobile phone would enable the PAN to be constantly online. The strongest candidate to provide the cheap short-range radio links necessary to enable such networks is the Bluetooth wireless technology. Seen from a networking perspective, a PAN will be expected to have participants, both of its own devices and guest devices from other PANs, continuously moving in and out of its coverage. To cope with this volatile nature of the network, the concept of ad hoc networking may be applied to create robust and flexible connectivity. A major technical step is taken when the Bluetooth piconet network architecture, a strict star topology, is extended into a scatternet architecture, where piconets are interconnected. A consequence of creating scatternet-based PANs is that some nodes will form gateways between piconets, and these gateways must be capable of time sharing their presence In each piconet of which they are members. While the Bluetooth standard defines the gateway nodes, the actual mechanisms and algorithms that accomplish the interpiconet scheduling (IPS) are left rather open. Given the lack of research literature in the subject, an overall architecture for handling scheduling in a scatternet is presented. A family of feasible IPS algorithms, referred to as rendezvous point algorithms, is also introduced and discussed.