Dear Shubho and all,
Thank you for posting the SP text. We appreciate the opportunity to provide comments on your Straw Poll (SP).
First and foremost, we would like to draw attention to the general understanding established at the May IEEE meeting when DSO was SP/motioned in. At that meeting, there was a consensus that DSO operation would be inclusive of 20MHz devices and not exclude them from DSO operations. This understanding was also reflected in the official minutes of that meeting.
Specific Concern with SP Bullet #1: We strongly disagree with the first bullet of the SP, which proposes that DSO should be exclusive to 80MHz and 160MHz UHR STAs. This approach excludes 20MHz-only STAs, which represent a significant and critical portion of the IoT ecosystem. Excluding these devices from the DSO specifications would create unnecessary disadvantages for this segment and hinder innovation in the IoT space.
We would also like to take his opportunity to like to reinforce our position by addressing some of the previously raised concerns, and provide technical and Practical Justifications for 20MHz Inclusion. Below is a summary of our arguments:
#1 Understanding Restrictions in 36.3.2.6
IN the past, some concerns were raised regarding RU allocation restrictions. Let’s break these restrictions down in to 2 cases
- DL related RU allocation restrictions
- UL related RU allocation restrictions
In case of DL, according to 36.3.2.6:
- 242, 106 or 52 tone RUs : There are no restrictions for allocating these RUs to 20MHz devices during DL transmissions..
- 26 tone RUs: Only 4 out of 37 RUs are disallowed, leaving sufficient options for scheduling 20MHz-only devices
In case of UL, according to 36.3.2.6:
- 242-tone RU: As noted, the transmission of 242-tone RUs is already disallowed due to performance degradation concerns.
- 106-tone and 52-tone RUs: There are no restrictions for these RUs.
- 26-tone RUs: Only 8 out of 72 RUs are disallowed, leaving the vast majority of RU options unaffected
In case of MRU combinations, for the DL and UL:
- 4 out of a total of 8, 26 + 52 MRUs are allowed in case of 80 MHz
- 8 out of a total 16, 26 + 52 MRUs are allowed in case of 160 MHz
Performance degradation:
- For the DL, our study should that there is no noticeable performance degradation until MCS 9.
- The 242 tone allocation in UL was alredy disallowed due to performance reason.
Conclusion: Even with these restrictions, the number of viable RU allocation options remains substantial, ensuring the AP scheduler has enough flexibility to schedule 20MHz devices efficiently..
#2: Addressing Concerns of Performance Degradation
- Our studies show no noticeable performance degradation up to MCS 9 when using 20MHz-only devices in DSO-enabled operations.
- The 242-tone RU allocation for UL is already disallowed where performance issues might arise.
- From a tone mapping perspective, the AP does not differentiate between transmissions from a 20MHz device or an 80MHz device.
- The presence of a small RU for a 20MHz-only STA does not introduce any additional complexities or inefficiencies compared to scheduling in non-DSO operations.
- DSO allows 20MHz-only devices to operate on cleaner subchannels, reducing wasted bandwidth in scenarios where 20MHz RUs would otherwise occupy portions of a wider (80MHz or 160MHz) operating bandwidth.
#3: Sounding, Beamforming, and (MU-)MIMO Considerations
- Scheduling complexity for a mix of 80MHz and 20MHz devices exists regardless of DSO.
- DSO does not introduce additional requirements for beamforming, sounding, or (MU-)MIMO operations beyond those already necessary for mixed-bandwidth device environments.
- The AP scheduler must already handle these cases in non-DSO operations, making DSO scheduling complexity comparable to non-DSO scenarios.
#4: Power Consumption and Use Case Flexibility
- While power consumption reduction is a possible benefit for utilizing DSO for 20 MHz only STAs in some use cases, but it is clearly not the only goal.
- For media centric IoT applications and use cases, in particular, that involve streaming video (e.g. Mevo, Automotive Infotainment, Webex etc, and several other Streaming, Smart Home, IIoT, Automotive, use cases), moving to a cleaner channel, enabled by DSO, benefit significantly by seeing improved latency, enhanced reliability and overall increase in system throughput.
- Moving 20MHz devices to cleaner channels via DSO reduces retransmissions. The power consumption reduction that will result from these lesser retransmissions provides an overall network benefit (rather than a direct device benefit primarily).
Summary
- Flexibility of RU Allocation: Even with the restrictions in place, there are still sufficient RU allocation options available for 20MHz-only devices, both in DL and UL.
- Performance Degradation: Restrictions that eliminate performance degradation are already in place, leaving viable configurations that maintain system performance.
- Sounding and Scheduling Complexity: DSO does not introduce additional complexities for scheduling or beamforming beyond existing requirements in non-DSO environments.
- Use Case Flexibility: DSO should remain an option to support diverse use cases where its benefits (e.g., reduced retransmissions, improved reliability) may outweigh the concerns raised.
Recommendation: Inclusivity and Market Relevance
The IEEE standard should not be the place to disallow DSO for 20MHz-only devices. Excluding 20MHz-only devices from DSO operations would be short-sighted and counterproductive for several reasons:
- Market Relevance: 20MHz devices dominate the IoT ecosystem, representing a significant and growing market segment. Excluding them creates barriers to adoption and disadvantages a substantial portion of the industry.
- Diversity of Use Cases: IEEE standards should aim to accommodate a diverse range of use cases, including those where 20MHz devices are critical (e.g., smart homes, healthcare IoT, automotive, and industrial automation).
- Flexibility for the Industry: The IEEE standard should provide a framework that allows the market to decide on the adoption of DSO features, rather than preemptively excluding an entire class of devices. This discussion is perhaps better suited for the Wi-Fi Alliance.
In closing, we urge the group to consider the broader implications of this decision. Voting to exclude 20MHz-only devices from DSO will set a precedent that could limit innovation and growth in key areas. Instead, we propose that DSO remain inclusive of 20MHz-only devices, allowing the market to explore and adopt this feature where it provides value.
We look forward to a fruitful discussion during the meeting and remain hopeful that the group will recognize the importance of maintaining inclusivity in the specification.
Thanks and Kind Regards,
Rakesh
From: Shubhodeep Adhikari <00000c144a46bcee-dmarc-request@xxxxxxxxxxxxxxxxx>
Sent: Friday, April 18, 2025 11:53 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBN] SP request for DSO
Hi Alfred,
Please queue the following SP on DSO to the TGbn MAC agenda.
Do you agree that:
· only 80MHz UHR STAs and 160MHz UHR STAs can be DSO STAs
· the DSO ICF-ICR exchange and the PPDUs that follows it shall only be between UHR STAs
· one 80MHz subband in 320MHz BSS can be a DSO subband
§ whether more than one 80MHz subband can be a DSO subband in 320MHz BSS TBD
· Secondary 80MHz in 160MHz BSS can be a DSO subband
· Secondary 160MHz in 320MHz BSS can be a DSO subband
Supporting document: 11-24/1588r1
Regards,
Shubho
Please queue the following two SPs on DSO topic to the TGbn MAC adhoc agenda.
- Do you support that in the DSO ICF, the AP indicates to a DSO STA to switch to a DSO sub-band
- Upon reception of the DSO ICF, the DSO STA shall
- transition to the DSO sub-band,
- transmit the response in the DSO sub-band a SIFS after the end of the DSO ICF
- be ready to receive frames or be triggered to transmit frames, subject to its spatial stream capabilities and operation mode, in the DSO sub-band (derived from the DSO ICF), a SIFS after the end of the response frame
- The baseline rules for CS required are followed.
- Supporting document: 11-24/1553
- Do you agree that if no non-AP STA that is assigned resources in the primary 20 MHz responds to the initial Control frame and there is at least one response on other channels, the AP shall do one of the following:
- Terminate the frame exchange sequence with all non-AP STAs, or
- Continue the frame exchange sequence by ensuring that the primary 20 MHz is occupied
- Supporting document: 11-24/1553
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