# MTRSRP: Joint Design of Multi-Triangular Ring and Self-Routing Protocol for BLE Networks
## 2 Related Work  
A notable surge in interest in BLE technology has been observed in recent years. The conventional star topology design has demonstrated limitations regarding network coverage and diversity of available end-to-end paths. Consequently, alternative technologies have been extensively explored to overcome these constraints, particularly through the use of mesh-based approaches for IoT applications [14]. Two primary strategies have emerged in BLE networks to address coverage limitations. The first strategy focuses on expanding the radio range within an existing star-based topology by adjusting the BLE bandwidth in the physical layer. Conversely, the second strategy involves implementing a BLEmesh network, which introduces complexities in the mesh topology configuration but effectively overcomes the coverage and path diversity limitations inherent in a star topology. A novel on-demand multi-hop routing protocol was introduced in [10] and was specifically tailored for BLE in wireless sensor networks (WSNs). Initially, the network nodes alternate between advertisers and scanners to identify nearby nodes. Subsequently, the source nodes send route request messages to their designated master nodes to locate the destination node and determine the shortest path for packet transmission. This methodology is suitable for implementing the BLE routing protocol in hardware, and its effectiveness was verified through a performance evaluation in a scatternet comprising ten BLE nodes. BLE technology presents an intriguing opportunity to develop cost-effective industrial WSNs, offering advantages such as low energy consumption and high adaptability. A previous study [15] outlined a configuration approach that ensured controlled message latencies within star topologies. This method involves implementing a mesh-based topology over BLE to maintain limited latencies during packet transmission. Furthermore, to facilitate real-time communication, the integration of a multi-hop real-time BLE (MRT-BLE) protocol within BLE was proposed, prioritizing bounded packet delays, particularly for mesh networks [16]. This paper presented the experimental findings from a realistic test environment and analyzed the worst-case end-to-end packet delay scenarios for MRT-BLE. Another study [17] proposed a method for addressing dynamic address allocation and network topology mapping in BLE environments. This approach integrated an automatic configuration protocol for defining and managing IDs along with a proactive source routing algorithm for route discovery, maintenance, and mapping within the spanning tree setup. To assess the practicality of energy constraints in BLE, the performance of a battery-limited Bluetooth mesh protocol was evaluated using real hardware to establish models for current consumption, lifespan, and energy expenditure per bit [18]. Furthermore, this study investigated the applicability and limitations of the Bluetooth mesh as an IoT solution considering the power supply leveraging the Bluetooth mesh architecture. A previous study [12] introduced a CORP topology to facilitate multi-hop communication within BLE networks. Using cluster-based flooding, the protocol effectively manages packet flooding during route discovery, reducing energy consumption compared with traditional flooding methods. This is particularly advantageous because conventional flooding schemes may lead to significant route discovery overheads because packets are forwarded by any node within the mesh connections. Furthermore, a dual-ring tree approach [7] was proposed for BLE networks by incorporating predefined parameters to establish the desired dual-ring tree topology based on single- and multi-hop scenarios. Distributed and localized algorithms have been employed in dense areas to handle multi- and single-hop communication. The resulting dual-ring subnet formed the core network, which was then expanded by a tree-based subnet to cover the less-populated regions.