SWRA733 March   2022 WL1807MOD , WL1837MOD

 

  1.   Trademarks
  2.   Acronyms
  3. 1Introduction
  4. 2 Single-Channel Versus Multi-Channel
    1. 2.1 MRSC Single Radio Network Topology
    2. 2.2 MRMC Single Radio Network Topology
    3. 2.3 Experiment and Results
  5. 3Multi-Channel Challenges and Requirements
    1. 3.1 802.11 Spec Enablers for Role Switch Protections
    2. 3.2 Role Switch Protection Implementations
      1. 3.2.1 AP Based Roles
      2. 3.2.2 STA Based Roles
    3. 3.3 Single Radio Multi-Channel Challenges
    4. 3.4 Single Radio Multi-Channel Key Requirements
  6. 4WL18xx™ Multi-Channel Implementations
    1. 4.1 Arranging the Role Activity Requests by Priority
    2. 4.2 Scheduling the Role Activities
    3. 4.3 Leveraging MRMC to Improve WLAN-BT Coexistence
  7. 5Conclusions
  8.   Appendix

3.3 Single Radio Multi-Channel Challenges

The MRMC uses a time division solution between the roles and therefore it is required to manage each of the role’s absences from their channel in order to protect it. An unmanaged concurrent operation of multiple WALN role on a single radio chip can result in an unstable and unreliable system and even expose the system to disconnections, low performance and bad user experience. For example, the implications of unmanaged AP absence from its operating channel will cause the connected STAs to have many data transmission retries or poll for data without receiving the ACK or data back from the AP. The system can then suffer from rate drops or even disconnections. Similarly, new STAs might fail to connect. Another example for a challenge in MRMC single radio is handling unmanaged STA absence from the channel. In this case, the connected AP may send data and receive no ACK which might lead to rate drop, disconnections and lost beacons, DTIMs and multicast data. Table 3-1 summarizes the challenges:

Table 3-1 Multi-Role Multi-Channel Single-Radio Implication of Unmanaged Role Absence
Implication / WLAN Role Unmanaged AP absence Unmanaged STA absence
Rate drops Connected STAs try to send or poll for data and receive no ACK/data results in rate drop Connected AP try to send data and receive no ACK results in rate drop
Disconnections Connected STAs lost too many beacons and disconnect from the AP Connected AP try to send data and receive no ACK results in disconnection
Network Integrity New STAs fail to complete the connection process STA might lose channel switch indication
Low Performance Bi-directional traffic is lower due to multiple retries and low data rate