P-RASP: An efficient packet reassembly and segmentation protocol for Bluetooth low data rate applications

Bluetooth (BT) is being applied to more and more applications in wireless sensor networks (WSNs). Studies indicate that during data transmission of the lower data rate Asynchronous Connection-oriented link (ACL) applications, BT devices have to run with small size baseband packets (e.g. 3-DH1) and BT controllers have to do many polling operations to maintain system synchronization. To reduce the unnecessary polling, BT devices often negotiate an agreed idle/sleep interval duration using the sniff mode, which allow BT devices to enter a low power state. In this paper, a Packet Reassembly and Segmentation Protocol (P-RASP) in the BT baseband is proposed to re-assemble small host controller interface (HCI) data packets in the transmit buffers to a larger one, so that the link manager can assemble a larger baseband packet type (e.g. 3-DH5) with full payload. Furthermore, the P-RASP core functionality, the corresponding operations, procedure details and performance evaluation within appropriate scenarios are studied. Experimental results show the P-RASP can reduce the active time of a BT link and offer efficient packet transmission.