A Hybrid BLE-Wi-Fi Communication Architecture for Adaptive Imaging in Wireless Capsule Endoscopy

TL;DR

Wireless capsule endoscopy is constrained by limited bandwidth, hindering imaging resolution and frame rate. The authors introduce a hybrid BLE–Wi‑Fi architecture that exploits BLE’s low power and Wi‑Fi’s high throughput, coupled with a frame-boundary synchronized switching mechanism to achieve lossless, adaptive imaging. Using tissue-mimicking experiments with adaptive TXP and a frame-boundary switching protocol, they quantify BLE throughput (~800 kbps) and RSSI stability, compare 2.4 GHz Wi‑Fi STA and 5 GHz configurations, and analyze how image size impacts handover latency (e.g., ~370 ms BLE→Wi‑Fi and ~39 ms Wi‑Fi→BLE for 40 KB frames). The results validate robust, energy-efficient mode switching and provide practical guidelines for next-generation autonomous WCE systems and their imaging workflows.

Abstract

Wireless capsule endoscopy (WCE) is fundamentally constrained by limited wireless bandwidth, resulting in low imaging resolution and frame rate, which can cause motion blur and missed lesions. Although adaptive frame-rate schemes have been explored to accommodate transient gastrointestinal (GI) motility, these approaches typically require sacrificing image resolution. The use of higher-frequency communication bands is further limited by increased tissue attenuation. To address these challenges, we propose a hybrid Bluetooth Low Energy (BLE) and WiFi communication architecture that combines the low-power operation of BLE with the high data throughput of WiFi. We systematically evaluate the performance of BLE and WiFi under tissue-mimicking conditions by measuring throughput, received signal strength indicator (RSSI), and power consumption. The results demonstrate that amplified BLE with an adaptive transmission power control strategy provides a stable frame rate at low power consumption, while 2.4 GHz WiFi operating in station mode is the most suitable high-throughput communication configuration for WCE. Compared with WiFi, BLE reduces power consumption by approximately ten times, whereas WiFi achieves up to ten times higher throughput. To reconcile these complementary trade-offs, we further introduce a hybrid system with a frame-boundary-synchronized switching mechanism to ensure lossless data transmission during BLE and WiFi transitions. Experimental results show that the switching latency from BLE to WiFi is approximately 92.66 ms, which is longer than the WiFi-to-BLE switching latency of 15.49 ms when transmitting 10 kB image payloads. Overall, the proposed hybrid BLE and WiFi system enables robust, lossless, and energy-efficient mode switching, supports adaptive imaging, and advances the development of next-generation autonomous WCE platforms.

Figures (5)

• Figure 1: Hybrid BLE--Wi-Fi communication architecture for wireless capsule endoscopy, enabling energy-efficient operation with lossless switching between low-frame-rate BLE transmission and high-frame-rate Wi-Fi image streaming.
• Figure 2: Bidirectional protocol switching between BLE and Wi-Fi. The system performs handovers using a frame-boundary–synchronized mechanism, ensuring lossless data transmission during protocol transitions.
• Figure 3: Comparison of BLE and Wi-Fi transmission characteristics in air and at various water depths. BLE operates at a fixed TXP of 3 dBm or adaptively, while Wi-Fi uses dynamic TXP under four configurations: 2.4 GHz STA, 2.4 GHz AP, 5 GHz STA, and 5 GHz AP.
• Figure 4: Time-aligned measurements of power consumption and frame rate during BLE$\rightarrow$Wi-Fi and Wi-Fi$\rightarrow$BLE switching. The proposed frame-synchronized handover mechanism enables stable FPS and prevents data loss.
• Figure 5: Switching latency between Wi-Fi and BLE under different image sizes. The measured delays include transitions from BLE$\rightarrow$Wi-Fi and from Wi-Fi$\rightarrow$BLE for image sizes of 10 - 40 KB.