Basestation collaboration in Bluetooth voice networks

In the near future Bluetooth will be embedded into many different types of mobile and portable devices. Initially this will provide simple wire replacement functions for applications such as hands-free headsets for cellular radio. However, this will also enable future picocellular services such as real-time voice and data. There are many possible applications for this such as telephone lounges in airports, shopping malls and other public places. We consider several Bluetooth-based telephony basestation (BS) designs. Since the number of SCO links per Bluetooth node is very limited, the designs consider the use of multiple overlapping Bluetooth basestations/chips. The first scheme is a direct implementation of the telephony profile where the Bluetooth basestations operate independently, without any coordination. When a mobile comes within range of the system, it associates with a basestation using the normal inquiry/page process. The second scheme, BBSM (Bluetooth basestation with migration), reduces the probability of blocking by having mobile nodes re-associate with available basestations when their current basestation is about to become blocked by SCO links. This improves the performance of the system from a blocking standpoint, but can be very spectrally wasteful. The third design, BBSS (Bluetooth basestation with standby), further improves blocking performance and decreases the wasteful effects of "node migration storms" which can occur in BBSM. We also include results for a design which uses ACL-based voice links. This scheme gives the best performance but has the disadvantage that more complex vocoding is required.