Analysis of the Bluetooth device discovery protocol

Abstract

Device discovery and connection establishment are fundamental to communication between two Bluetooth (BT) devices. In this paper, we give an analytical model of the time it takes for the master in a piconet to discover one slave. We show that, even in the absence of packet interference, the discovery time can be long in some instances. We have simulated the discovery protocol by actually implementing it to validate the analytical model. By means of simulations, we show how discovery time is affected by (i) the presence of multiple potential slaves, and (ii) changes in the maximum backoff limit. Using simulation studies we observed the effectiveness of two proposed improvements to device discovery, namely, (i) avoiding repetitions of the A and B trains before a train switch, and (ii) eliminating the idea of random backoff, or reducing the backoff limit. We show that discovery time can be reduced by avoiding repetitions of the A and B trains before a train switch. However, complete elimination of the random backoff is not a good idea, as discovery time will be too long when the number of BT devices is large. Instead, choosing a small backoff limit of 250-300 slots is highly effective in reducing discovery time even in the presence of a large number (say, 50) of potential slaves.

Analyzing Pedestrian Flows Based on Wi-Fi and Bluetooth Captures

“…Commonly, a Bluetooth device following this protocol is said to be "discoverable" meaning that it remains passive and listens for inquiry requests on a selected single inquiry scan physical channel. The device will answer to inquiry requests received on this channel with an inquiry response [5] Modern smartphones are not in the inquiry scan state by default and thus, they will not be discovered on any inquiry scan physical channel. However, in public areas with heterogeneous crowds like on airports, it is suspected to capture a noticeable amount of discoverable Bluetooth devices, mainly from older generation.…”

eDiscovery: Energy efficient device discovery for mobile opportunistic communications

“…For scanning devices, Bluetooth controls their scanning duration and frequency with two parameters, scan window and scan interval. 5. http://www.cs.uc.edu/ ∼ cdmc/ucbt/…”

“…Based on Bluetooth specification v1.1, Peterson et al [23] derive rigorous expressions for the inquiry-time probability distribution of two Bluetooth devices that want to discover each other. Chakraborty et al [5] present an analytical model of the time of Bluetooth device discovery protocol. Liberatore et al [18] solve the problem of long discovery duration of Bluetooth due to its half-duplex discovery process by the addition of another Bluetooth radio.…”

“…First, we add the theoretical analysis of device-discovery missing probability (Section 5), which motivates us to design the eDiscovery protocol. Second, we port the implementation of eDiscovery into the ns-2 simulator enhanced with the UCBT Bluetooth module 5 and offer a detailed evaluation of its parameters (Section 8). We also compare the performance of eDiscovery and STAR with more network topologies using ns-2 simulations.…”

Formal Verification of Device Discovery Mechanism using UPPAAL

“…The master follows the two procedures to discover the device as follow [20,15]  Page: After receiving the address and clock values of a (potential) slave device, the master communicate with the device via the paging process. During the paging process, the master establishes a connection with a slave [10]. The paging procedure takes a very short time (at most 20 ms) while the inquiry procedure might cause a significant delay (up to a few seconds on average) [14].…”