Wireless Coexistence via Network Allocation Vector Scheduling
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Solution Overview
Problem
Incorporating multiple wireless protocols in a single device, such as WLAN and Bluetooth, leads to interference and saturation issues due to time multiplexed access to the wireless medium, resulting in performance deterioration and collisions.
Innovation Solution
A wireless apparatus with scheduling logic that determines whether a WLAN communication will complete before the end of its active time period, and if not, transmits a WLAN packet encoding a network allocation vector (NAV) value to prevent the access point from using the medium until the end of the subsequent time period, allowing the Bluetooth protocol to access the medium without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time multiplexed access is used for multiple wireless protocols, then interference between protocols is reduced, but access delay and collisions increase due to waiting periods
Solution Approach 1:
The NAV value is set in advance to reserve the wireless medium for future Bluetooth transmissions. By predicting future protocol needs and preemptively marking the medium as occupied, the system avoids both interference and unnecessary waiting periods, as other WLAN devices will respect the NAV and defer access.
2Productivity
If WLAN controller transmits packets during its active time period, then WLAN communication efficiency is improved, but collisions occur with Bluetooth packets during protocol switching
Solution Approach 1:
The system performs preliminary assessment of whether WLAN communication can complete before Bluetooth active period begins. If not, it preemptively sets the NAV value to prevent collisions before they occur, ensuring both WLAN efficiency and collision avoidance.
Solution Approach 2:
The NAV value acts as an intermediary mechanism that coordinates between WLAN and Bluetooth protocols. By encoding the reserved time period in the NAV field of WLAN frames, it mediates access rights and prevents collisions without requiring direct intervention in the other protocol's transmission.
3Adaptability or versatility
If multiple wireless protocols are incorporated in one device, then device versatility is improved, but coexistence problems and medium saturation occur
Solution Approach 1:
The scheduling logic performs preliminary determination of protocol active periods and preemptively reserves medium access rights using NAV values. This advance planning enables multiple protocols to coexist without interference, as each protocol's time requirements are predetermined and enforced through NAV reservations.
Data Source
AI summary
A wireless apparatus includes a wireless transceiver, a WLAN controller and a second controller coupled to the wireless transceiver. The WLAN controller is configured to send/receive packets in accordance with a WLAN protocol, and the second controller is configured to send/receive packets in accordance with a second wireless protocol. The apparatus includes scheduling logic that determines whether a WLAN communication will complete before an end of a WLAN active time period. If the scheduling logic determines that the WLAN communication will not complete before the end of the WLAN active time period, the scheduling logic causes the WLAN controller to transmit a WLAN packet that encodes a NAV value that prevents an access point from using the wireless medium until an end of second time period. The second controller is configured to use the wireless medium during the second time period.