An Adaptive Connection-Establishment Timeout Configuration Method for Bluetooth MANETs in Control Packet Loss Environments

Abstract

Bluetooth MANETs, which consist of Bluetooth-enabled terminals, are a prospective methodology for mobile ad hoc networks (MANETs). Since Bluetooth is a connection-oriented and a low-power-consumption communication method, terminals must execute time-consuming connection establishment procedures in advance. We have to solve the following two problems for Bluetooth MANETs: (1) since terminals move within fields, terminals must establish their connection within a limited time. In addition, (2) since Bluetooth has a shorter range than other technologies, established connections are easily disrupted. In order to solve problem (1), a low-latency connection establishment method has been proposed. However, there is no countermeasure for problem (2). Therefore, the possibility of rapid re-establishment for connections ought to be investigated. In this paper, we have proposed a new adaptive connection-establishment timeout configuration method for environments with control packet loss. Our proposed method employs an adjustment mechanism for control packet loss. We have also implemented our proposed method on Raspberry Pi in order to evaluate our proposed method. To design our proposed method, we have conducted preliminary experiments to investigate the effects on varied connection-establishment timeouts. As a result, we have found that the minimum connection-establishment timeout is 2 seconds. At the same time, we have found that connection establishment failure rates increased as connection-establishment timeouts became shorter than 2 seconds. Especially, when connection-establishment timeouts were less than 2 seconds, the latency of the connection establishment became extremely long. This is due to the presence of a race condition between the processing time of control packets and the connection-establishment timeouts. From these results, we have set an adjustable interval of connection-establishment timeouts between 2 to 5 seconds. 5 seconds is the native default value of Bluetooth’s connection-establishment time-out. We have also conducted experiments of our proposed method in varying packet loss rate scenarios, and have confirmed the effectiveness of our proposed method.