Bluetooth Piconets Research Articles

Impact of Interfering Bluetooth Piconets on a Collocated $p$-Persistent CSMA-Based WLAN

In this paper, the effect of cochanneled Bluetooth (BT) piconets on a carrier-sense multiple-access (CSMA)-based wireless local area network (WLAN) is investigated. Specifically, the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> -persistent CSMA protocol is considered for WLANs, and the probability of error of a WLAN packet is calculated in the presence of interfering BT packets of different lengths and variable piconet traffic loads and as a function of the BT's frequency-hopping guard time. The probability derivation is then used in conjunction with the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> -persistent CSMA throughput and delay formulations to examine its net performance in the presence of BT interference. Simulations have been used to corroborate the analytical results, which indicate that the presence of just one fully loaded interfering BT piconet reduces the peak CSMA throughput by 42%. Furthermore, we show that under fully loaded BT traffic conditions, the effect of more shorter BT packet transmissions on the CSMA delay performance can outweigh the interference impact of a higher number of BT piconets with longer packet transmissions.

AES Algorithm of Improving WPAN Throughput

The throughput of WPAN (Wireless Personal Area Network) based on Bluetooth was decided by the interference of Bluetooth piconets in the network. The interference was decided by the hamming correlation of Bluetooth FH (Frequency Hopping) selected sequence. In order to improve the WPAN throughput, the WPAN model and data packet collision model were built and the relations about WPAN throughput, the maximum hamming correlation of FH selected sequence, the numbers of Bluetooth piconets and the SNR of channel were analyzed. The functions of WPAN throughput were deduced. After analyzing the performance of Bluetooth FH selected sequence, the original algorithm was replaced by the AES (Advanced Encryption Standard) algorithm. The theoretical analysis proved that the AES FH sequences selected algorithm could improve the WPAN throughput. The simulation results proved the theoretical analysis. The test result with ARM926EJs SoC (System on Chip) + RF (Radio Frequency) chip nRF2401 and CSR's Bluecore4 Bluetooth module got the same conclusion. All of these could prove that the AES algorithm can improve the WPAN throughput efficiently.

One Tooth, Two Tooth, Green Tooth, Bluetooth, Part I

One Tooth, Two Tooth, Green Tooth, Bluetooth, Part I

Collision analysis for coexistence of multiple bluetooth piconets and WLAN with dual channel transmission

Co-channel interference (CCI) has become an important problem with the increasing deployment of wireless networks in the unlicensed frequency band. The existing Bluetooth scheme avoids collisions by modifying its hop sequences in the presence of WLAN. We propose a frequency diversity technique, namely dual channel transmission (DCT), which reduces packet error rate (PER) due to CCI when multiple Bluetooth piconets coexist with or without WLAN interference. The idea of DCT is to transmit the same packet on two distinct frequency hopped channels simultaneously and the power used in each channel is half of what would be used in single channel transmission (SCT). Since a packet is successfully received if at least one channel survives, the PER is reduced even when multiple piconets coexist. Further, the two channels of DCT are separated by at least 22 MHz to ensure robustness to WLAN interference. Theoretic analysis and numerical simulations on key metrics - PER, throughput, and transmission time are presented to validate the proposed approach and quantify its advantages. Comparisons to other coexistence mechanisms also demonstrate the effectiveness of DCT.

Enhancing Performance of Bluetooth Piconets Using Priority Scheduling and Exponential Back-Off Mechanism

Bluetooth is a personal wireless communication technology and is being applied in many scenarios. It is an emerging standard for short range, low cost, low power wireless access technology. Current existing MAC (Medium Access Control) scheduling schemes only provide best-effort service for all masterslave connections. It is very challenging to provide QoS (Quality of Service) support for different connections due to the feature of Master Driven TDD (Time Division Duplex). However, there is no solution available to support both delay and bandwidth guarantees required by real time applications. This paper addresses the issue of how to enhance QoS support in a Bluetooth piconet. The Bluetooth specification proposes a Round Robin scheduler as possible solution for scheduling the transmissions in a Bluetooth Piconet. We propose an algorithm which will reduce the bandwidth waste and enhance the efficiency of network. We define token counters to estimate traffic of real-time slaves. To increase bandwidth utilization, a back-off mechanism is then presented for best-effort slaves to decrease the frequency of polling idle slaves. Simulation results demonstrate that our scheme achieves better performance over the Round Robin scheduling. Keywords—Piconet, Medium Access Control, Polling algorithm, Scheduling, QoS, Time Division Duplex (TDD).

Adaptive Packet-Level Interleaved FEC for Wireless Priority-Encoded Video Streaming

Packet-level Forward Error Control (FEC) for video streaming over a wireless network has received comparatively limited investigation, because of the delay introduced by the need to assemble a group of packets. However, packet-level interleaving when combined with FEC presents a remedy to time-correlated error bursts, though it can further increase delay if this issue is not addressed. This paper proposes adapting the overall degree of interleaved packet-level FEC according to the display deadlines of packets, transmit buffer occupation, and estimated video input to the wireless channel, all of which address the issue of delay. To guard against estimation error, the scheme applies a conservative adaptation policy, which accounts for picture type importance to ensure that display deadlines are met, thus avoiding this defect of interleaving. The paper additionally introduces a greedy algorithm that effectively groups packet-level FEC protection according to packet priority. Priority encoding adds extra protection during deep fades. As feedback is not required, the interleaving scheme is suitable for all forms of video broadcast. A Bluetooth piconet demonstrates the packet-level FEC interleaving scheme, which provides higher quality delivered video compared to the industry-standard Pro-MPEG Cop#3r2 interleaving scheme.

A random graph-based model to analyze packet interference between frequency hopping systems with an application to Bluetooth

In this paper, we present a graph-based model for analyzing interference between two frequency hopping systems for wireless communication. Informally, frequency hopping means that successive packets are transmitted on different frequencies from a pseudo-random sequence. The frequency band occupied by a packet may be narrow or wide. Our model is based on the concept of probabilistic graphs, where a node represents a “channel” and an edge denotes the probability of interference between two packets belonging to two different channels. Two packets on two channels are said to be mutually interfering if the two packets overlap in time and are transmitted on the same frequency. Thus, from the viewpoint of probabilistic graphs, the expected number of nodes with at least one incident edge is a measure of packet interference in a collection of wireless channels. We apply this model of packet interference to a heterogeneous cluster of Bluetooth piconets, where a piconet could be either of 79-hop type or of 23-hop type. Though the 23-hop type has been phased out, we use it as an example in this paper.

A new insight into Bluetooth piconets coexistence

AbstractThis paper discusses Bluetooth piconets coexistence. We use an approach which is totally different from those used traditionally with Bluetooth (probabilistic collision models). We show how it is possible to obtain an interference‐free Bluetooth environment in some conditions, for certain kinds of Bluetooth devices, using the properties of the Bluetooth frequency hopping system. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Mobile Message Passing using a Scatternet Framework

The Mobile Message Passing Interface is a library which implements MPI functionality on Bluetooth enabled mobile phones. It provides many of the functions available in MPI, including point-to-point and global communication. The main restriction of the library is that it was designed to work over Bluetooth piconets. Piconet based networks provide for a maximum of eight devices connected together simultaneously. This limits the libraries usefulness for parallel computing. A solution to solve this problem is presented that provides the same functionality as the original Mobile MPI library, but implemented over a Bluetooth scatternet. A scatternet may be defined as a number of piconets interconnected by common node(s). An outline of the scatternet design is explained and its major components discussed.

Performance analysis of single Bluetooth piconet in error-prone environments

This paper analyzes the performance of a Bluetooth piconet in error-prone environments. A statistical characterization of a waiting time, an end-to-end delay, and a goodput are derived analytically in terms of the arrival rates, the number of slaves, and the packet error rate (PER). For simplicity, half-symmetric piconet is assumed in this analysis. Both exhaustive and limited scheduling are considered. The analytic results are validated by simulations.

New bluetooth interconnection methods: Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS)

In a large scale Bluetooth network, the permanent Scatternet is regarded as the only method to interconnect Piconets. But, many Bluetooth devices do not support Scatternet. When they support it, features are limited. Moreover, in high mobility situations, the permanent Scatternet is not useful because of the extremely high overhead caused by frequent disconnections and reconnections. We propose Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS) to interconnect Piconets and form a virtual Scatternet. In OBP, every Piconet continuously changes its stages and collects metadata from Piconets within communication range. If metadata shows the existence of useful data to transfer, an inter-piconet connection is made and data is transferred. TS can be used instead of using permanent Scatternet to interconnect Piconets when needed. TS does not require large Scatternet formations and complex maintenance schemes. Moreover, it does not keep routing information. In this paper, we introduce and illustrate the OBP and TS concepts. We then compare throughput and efficiency of OBP and TS with respect to Scatternet.

QoS management middleware solutions for Bluetooth audio distribution

A primary challenge in the mobile Internet scenario is the dynamic differentiation of provided levels of Quality of Service (QoS) depending on client characteristics and current resource availability. In this context, the paper presents how the application-level ubiQoS middleware supports the provisioning of audio applications with different QoS levels over the last Bluetooth segment to wireless devices. To this purpose, ubiQoS dynamically deploys mobile proxies, acting as masters in Bluetooth piconets, to properly configure and manage Bluetooth connections at runtime. Audio applications working on top of ubiQoS can easily exploit differentiated QoS by simply specifying different user classes and terminal profiles. ubiQoS proxies exploit JSR82ext, a newly developed Java library that extends the JSR82 specification for Java-based Bluetooth communication facilities with richer QoS management functions for all types of Bluetooth connections. The reported experimental results show that our Java-based implementation can dynamically support differentiated QoS levels for audio traffic, with an efficient usage of the available Bluetooth bandwidth.

Strategies for adaptive frequency hopping in the unlicensed bands

Mechanisms based on frequency hopping have been widely used to enable short-range wireless networks to use resources from the unlicensed spectrum without frequency planning. Bluetooth piconet is a prime example of an FH-based network with unlicensed operation. As a price for open access, the piconet may experience adverse interference from other collocated FH piconets or other wireless devices that are transmitting in the same unlicensed band. A basic approach to mitigate this interference is that the piconet applies adaptive FH (AFH) and attempts to hop over a set (hopset) of less interfered channels. On the other hand, the regulation of unlicensed operation sets constraints on possible hopset adaptations. In this article we present two novel AFH strategies: adaptive frequency rolling (AFR) and dynamic AFH (DAFH). AFR avoids self-interference while preserving the dynamics of spectrum usage as required by the current regulation. DAFH is a distributed mechanism by which collocated piconets select nonconflicting hopsets while trying to keep the hopset size as large as possible. DAFH is not completely compliant with current regulations, but the rationale given for its design contains new rules of behavior for the unlicensed spectrum. Both approaches significantly outperform the conventional AFH strategy

Worst case response times in a Bluetooth piconet: scheduling combining 1-RR or E-RR with FIFO or EDF

In this paper, we focus on the Bluetooth wireless network, analyzing its ability to support the Quality of Service (QoS) requirements defined by QoS sensitive applications. The QoS perceived by the application depends on the scheduling mechanisms chosen at the medium access layer. Hence, we propose to evaluate the ability of different Bluetooth scheduling algorithms (1-RR/FIFO, 1-RR/EDF, E-RR/FIFO and E-RR/EDF) to guarantee bounded transmission delays. First, we establish a bound on the worst case response time of any sporadic message using a worst case analysis. We then compare the computed bounds with the worst case response times obtained by simulation for different traffic distributions and show in which configurations our bounds are tight. We finally compare those different schedulings and show how to extend our results on worst case response times taking into account message segmentation.

Modelling, Performance Analysis and Design of WPAN Systems

This paper covers the main issues that must be solved in order to design and analyse the performance of Wireless Personal Area Networks (WPANs) with the aid of simulation tools. We review state-of-the-art channel models to account for small- and large-scale propagation conditions in waveform- and system-level simulations. When dealing with waveform simulations, we also look at Montecarlo and importance sampling techniques that allow efficient estimation of error probabilities. Additionally, discrete channel models are introduced to efficiently link both waveform- and system-level approaches and we point out some methods to obtain the model parameters that are suitable for the wireless environment. The discussion of these techniques is complemented with two application examples that show the use of the different simulation levels for system design and performance study. With the paradigm of Bluetooth piconets we illustrate the usefulness of discrete channel models and we consider the design of an OFDM-based WPAN system to exemplify simulation from a waveform-level point of view.

Impact of Bluetooth MAC layer on the performance of TCP traffic

AbstractRecent updates of the Bluetooth specification have introduced significant changes in the Bluetooth protocol stack, including optional flow control. When the Bluetooth piconet is used to carry TCP traffic, complex interactions between TCP congestion control mechanisms and data link layer controls of Bluetooth will occur. In this paper, we model the performance of the piconet with TCP traffic, expressed through segment loss probability, round‐trip time, and goodput, through both probabilistic analysis and discrete‐event simulations. We show that satisfactory performance for TCP traffic may be obtained through proper dimensioning of the Bluetooth architecture parameters. Copyright © 2006 John Wiley &amp; Sons, Ltd.

Time-synchronised multi-piconet Bluetooth environments

Multiple Bluetooth piconets operating in the globally available 2.4 GHz industrial, scientific and medical (ISM) band are likely to co-exist in a physical environment, supporting applications such as wireless earphones, keyboards etc. An independently operating Bluetooth piconet will inevitably encounter the interference from collocated piconets, which results in both individual piconet and overall network performance degradation. We propose a simple time- synchronisation scheme among co-existing Bluetooth piconets that yields considerable performance improvements as compared to uncoordinated piconets. We introduce a new state to the Bluetooth link controller that does not require any changes to the existing Bluetooth hardware. The proposed scheme synchronises the collocated piconets in a totally blind fashion and incurs minimal overhead to the participating piconets. The performance of the scheme is measured by evaluating metrics such as packet error rate, individual piconet throughput and aggregate network throughput using an extensive analytical model. Furthermore, the effect of partial synchronisation among collocated piconets is also investigated.

Performance analysis of Bluetooth piconets with finite baseband buffers

AbstractWe analyze the performance of Bluetooth piconets under bursty traffic and finite buffer sizes. We model the joint probability distributions of uplink and downlink queues using the M[x]/G/1/K model with vacations and derive buffer blocking probabilities at slaves and at the master. The results, which are confirmed through simulations, provide some practical guidelines as to the sizing of device buffers. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Analytical Evaluation of Throughput for a Bluetooth Piconet with MAC Level Link Adaptation

In this paper a MAC level Link Adaptation (LA) strategy to be implemented in a Bluetooth piconet is investigated: the performance level that can be achieved in terms of throughput is derived and the comparison with the case of no LA is performed.Suitable definitions of the performance figures related to throughput are given and, starting from the knowledge of the physical level performance obtained via simulation, their analytical evaluation is performed in both the cases of LA and no LA.All aspects related to the propagation characteristics of the environment, the modulation/demodulation and coding/decoding techniques, and the multiple access strategy are taken into account in an integrated way; moreover a reference scenario analytically characterized along with a realistic scenario have been considered for the performance level assessment.The analytical results have been compared with simulation outcomes which confirm the validity of the approach adopted.

A Secure Protocol for Bluetooth Piconets Using Elliptic Curve Cryptography

In this article, the authors shall propose a new method for the implementation of secure Bluetooth piconets. Two requirements for the systems must be considered, i.e., privacy and authentication. Privacy ensures that an eavesdropper cannot intercept conversations between two slaves in piconets. Authentication ensures that service is not obtained fraudulently in order to avoid charge for usage. Additionally, a new key distribution scheme is designed for practical implementation in low-cost and low-power Bluetooth piconets. The proposed method employs elliptic curve cryptography for the use in the Bluetooth network. We have proper solutions to Bluetooth devices registration and Bluetooth piconets establishment. Furthermore, compared with Seo and Lee's protocol, the proposed scheme has a lower computation cost.