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Optimization of BLE Broadcast Mode in Offline Finding Network

L Zhang, C Feng, T Xia

TL;DR

The paper tackles reducing BLE neighbor discovery latency in Offline Finding Networks by proposing CPBIS, a two-interval broadcast mechanism that selects two broadcast intervals on opposite sides of the energy constraint boundary $A_{min}$. By constructing per-mode latency distributions via a Blender-based simulator and weighting them by market shares, CPBIS identifies troughs in the aggregated distribution to form an initial two-interval scheme, then iteratively re-optimizes and selects the optimal pair with a defined proportion to meet the power constraint via $ar A = \delta A_1 + (1-\delta) A_2$. The approach is validated on Nordic nRF52832 hardware, showing a weighted average discovery latency of $10.595$ s and a weighted discovery success rate of $98.3\%$, outperforming single-interval and alternating-interval baselines across two scan modes. These results demonstrate CPBIS’s practical potential to improve offline item finding experiences while respecting tag power budgets, and the work provides a complete methodology for configuring dual broadcast intervals in BLE NDP. The contributions include (i) a comprehensive two-interval screening framework, (ii) a distribution-based method to select interval pairs across multiple scan modes, and (iii) empirical validation on real hardware that confirms superior latency and reliability metrics.

Abstract

In the Offline Finding Network(OFN), offline Bluetooth tags broadcast to the surrounding area, the finder devices receiving the broadcast signal and upload location information to the IoT(Internet of Things) cloud servers, thereby achieving offline finding of lost items. This process is essentially a Bluetooth low energy (BLE) neighbor discovery process(NDP). In the process, the variety of Bluetooth scan modes caused by the scan interval and scan window settings affects the discovery latency of finder devices finding the tag broadcast packets. To optimize the experience of searching for lost devices, we propose the CPBIS-mechanism, a certain proportion broadcast-intervals screening mechanism that calculates the most suitable two broadcast intervals and their proportion for offline tags. This reduces discovery latency in the BLE NDP, improves the discovery success rate, further enhances the user experience. To our knowledge, we are the first to propose a comprehensive solution for configuring the broadcast interval parameters of advertisers in BLE NDP, particularly for configurations involving two or more broadcast intervals. We evaluated the results obtained by CPBIS on the nRF52832 chip. The data shows that the CPBIS-mechanism achieves relatively low discovery latencies for multiple scan modes.

Optimization of BLE Broadcast Mode in Offline Finding Network

TL;DR

The paper tackles reducing BLE neighbor discovery latency in Offline Finding Networks by proposing CPBIS, a two-interval broadcast mechanism that selects two broadcast intervals on opposite sides of the energy constraint boundary . By constructing per-mode latency distributions via a Blender-based simulator and weighting them by market shares, CPBIS identifies troughs in the aggregated distribution to form an initial two-interval scheme, then iteratively re-optimizes and selects the optimal pair with a defined proportion to meet the power constraint via . The approach is validated on Nordic nRF52832 hardware, showing a weighted average discovery latency of s and a weighted discovery success rate of , outperforming single-interval and alternating-interval baselines across two scan modes. These results demonstrate CPBIS’s practical potential to improve offline item finding experiences while respecting tag power budgets, and the work provides a complete methodology for configuring dual broadcast intervals in BLE NDP. The contributions include (i) a comprehensive two-interval screening framework, (ii) a distribution-based method to select interval pairs across multiple scan modes, and (iii) empirical validation on real hardware that confirms superior latency and reliability metrics.

Abstract

In the Offline Finding Network(OFN), offline Bluetooth tags broadcast to the surrounding area, the finder devices receiving the broadcast signal and upload location information to the IoT(Internet of Things) cloud servers, thereby achieving offline finding of lost items. This process is essentially a Bluetooth low energy (BLE) neighbor discovery process(NDP). In the process, the variety of Bluetooth scan modes caused by the scan interval and scan window settings affects the discovery latency of finder devices finding the tag broadcast packets. To optimize the experience of searching for lost devices, we propose the CPBIS-mechanism, a certain proportion broadcast-intervals screening mechanism that calculates the most suitable two broadcast intervals and their proportion for offline tags. This reduces discovery latency in the BLE NDP, improves the discovery success rate, further enhances the user experience. To our knowledge, we are the first to propose a comprehensive solution for configuring the broadcast interval parameters of advertisers in BLE NDP, particularly for configurations involving two or more broadcast intervals. We evaluated the results obtained by CPBIS on the nRF52832 chip. The data shows that the CPBIS-mechanism achieves relatively low discovery latencies for multiple scan modes.

Paper Structure

This paper contains 20 sections, 4 theorems, 13 equations, 23 figures, 2 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. motivation
  3. The possibility of controlling broadcast interval to reduce the discovery latency in BLE NDP
  4. The necessity of setting two broadcast intervals
  5. Overview of CPBIS-mechanism and background
  6. Offline Finding Network
  7. Key parameters in CPBIS-mechanism
  8. CPBIS-mechanism framework
  9. Obtain the broadcast interval-discovery latency distribution
  10. Initial screened broadcast interval sequence
  11. Interval sequence re-optimization
  12. Local optimum interval data pair sequence
  13. Optimal interval data pair
  14. Detailed Design
  15. Acquisition and optimization of initial screened broadcast interval sequence
  16. ...and 5 more sections

Key Result

Theorem 4.1

For any two-interval combination formed by the broadcast intervals from sets $B_L$ and $B_R$, there exists an equivalent broadcast interval $\overline{A}$ that satisfies the minimum equivalent broadcast interval constraint $\overline{A} \geq A_{min}$, and the resulting minimum discovery latency $L$

Figures (23)

  • Figure 1: Offline Finding Network
  • Figure 2: a CDF graph of discovery latency
  • Figure 3: "broadcast interval-discovery latency" distribution
  • Figure 4: Two local optimum broadcast intervals within a scan mode,and $A_{min}$
  • Figure 5: Offline Tag working mode
  • ...and 18 more figures

Theorems & Definitions (7)

  • Theorem 4.1
  • proof
  • Theorem 4.2
  • Theorem 4.2
  • proof
  • Theorem 4.3
  • proof