WLAN Bluetooth Coexistence via NAV and SCO Slot Monitoring

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Solution Overview

Problem

Bluetooth and IEEE 802.11 WLANs often experience collisions due to sharing the same unlicensed frequency band, leading to interference and inefficiencies in coexistence, particularly in applications like voice calls over Bluetooth earpieces and WLANs, where the timing of transmissions from access points is difficult to control.

Innovation Solution

Implementing a method that monitors Synchronous Connection Oriented (SCO) slots in Bluetooth networks, sets a Network Allocation Vector (NAV) at the access point to prevent collisions, and uses power save trigger frames to manage data transmissions, allowing for efficient coexistence by ensuring WLAN transmissions occur between SCO slots and avoiding interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If Bluetooth and WLAN share the same unlicensed frequency band, then spectrum utilization is improved, but transmission collisions and interference increase

Engineering Contradiction:

Improvespectrum utilizationVSAvoidtransmission collisions

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the shared frequency band into distinct time slots: SCO slots for Bluetooth transmissions and inter-SCO gaps for WLAN transmissions. This temporal segmentation allows both protocols to coexist in the same frequency band without colliding, as each protocol has dedicated transmission windows.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic SCO slots that occur at regular intervals in Bluetooth communication. By synchronizing WLAN transmissions to occur during the periodic inter-SCO gaps, the system creates a rhythmic pattern of alternating transmissions that prevents collisions while maintaining high spectrum utilization.

Inventive Principle:

Principle #19Periodic action

2Productivity

If access point transmits data continuously, then WLAN throughput is improved, but interference with Bluetooth SCO slots increases

Engineering Contradiction:

ImproveWLAN throughputVSAvoidinterference with Bluetooth

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses the NAV mechanism to preliminarily reserve inter-SCO gaps for WLAN transmissions before actual data transfer occurs. By setting the NAV duration to match the inter-SCO gap timing, the access point prepares the medium in advance, ensuring WLAN data can be transmitted without collision during these protected time windows.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts WLAN transmission timing based on Bluetooth SCO slot schedules. The access point monitors Bluetooth activity and adapts its transmission pattern to occur during inter-SCO gaps, creating a dynamic coexistence mechanism that maintains high WLAN throughput while avoiding fixed scheduling constraints.

Inventive Principle:

Principle #15Dynamics

3Productivity

If WLAN transmissions occur during SCO slots, then medium utilization is improved, but Bluetooth transmission reliability deteriorates

Engineering Contradiction:

Improvemedium utilizationVSAvoidBluetooth transmission reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by using the NAV mechanism to prevent WLAN transmissions during SCO slots before collisions can occur. The access point sets the NAV to be null or zero during SCO slot periods, proactively blocking WLAN transmissions that would otherwise interfere with Bluetooth voice communications, thereby protecting SCO slot reliability.

Inventive Principle:

Principle #9Preliminary anti-action

4Use of energy by moving object

If power save mode is used, then energy consumption is reduced, but transmission timing control becomes more difficult

Engineering Contradiction:

Improveenergy consumptionVSAvoidtransmission timing control

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent implements feedback mechanisms where the wireless device monitors the NAV values set by the access point and adjusts its power save polling timing accordingly. By receiving feedback about protected SCO slot periods through NAV settings, the device can synchronize its wake-up cycles to inter-SCO gaps, maintaining energy efficiency while achieving precise transmission timing control.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8989212B2Systems and methods for coexistence of WLAN and bluetooth networks

Publication Date: 2015.03.24 SYNAPTICS INC

AI summary

Systems and methods for coexistence of WLAN and Bluetooth networks are described. At least one embodiment includes a method for operating a wireless device in both a 802.11 network and a Bluetooth network. In accordance with some embodiments, the method comprises monitoring transmission of Synchronous Connection Oriented (SCO) slots over the Bluetooth network, informing an access point (AP) in the 802.11 network not to transmit to the device before the end of an SCO slot, transmitting a power save trigger to the AP to retrieve buffered data from the AP, and transmitting data to the AP.