Short SSW PHY Frame Structure for Faster Beamforming Training
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Solution Overview
Problem
The existing IEEE 802.11ad standard's Sector Level Sweep (SLS) procedure for beamforming training is inefficient as the length of SSW frames is fixed at 26 octets, leading to increased time requirements with an increasing number of sectors, hindering the completion of SLS.
Innovation Solution
A communication apparatus and method that generate shorter Sector Sweep (SSW) frames by replacing the Short SSW Feedback field with a Short Scrambled Basic Service Set ID (BSSID) field, using a PHY frame generating circuit to select the best sector and transmit the frame, thereby reducing frame length and completing SLS in less time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SSW frame length is fixed at 26 octets according to the IEEE 802.11ad standard, then the frame structure is standardized and compatible, but the time required to complete SLS increases as the number of sectors increases
Solution Approach 1:
The patent segments the traditional 26-octet SSW frame into a shortened version by removing unnecessary fields. Specifically, it eliminates the Direction subfield (1 octet) and the SSW Feedback subfield (2 octets), creating a compact SSW frame that is 23 octets long. This segmentation allows the frame to maintain essential functionality while reducing transmission time during sector sweeping operations.
Solution Approach 2:
The patent changes the frame length parameter from the standard 26 octets to a shortened 23 octets by modifying the frame structure. It introduces a new frame format where the Direction subfield is removed (since direction information can be inferred from the procedure phase) and the SSW Feedback subfield is eliminated (as feedback is handled separately). This parameter change directly reduces the time required to transmit each SSW frame during SLS.
2Measurement precision
If the number of sectors is increased to improve beamforming precision, then the communication quality is optimized, but the time required to complete SLS increases
Solution Approach 1:
The patent segments the SSW frame transmission process into shorter, more efficient units. By creating a shortened SSW frame format, each sector sweep transmission takes less time. This allows the system to sweep through more sectors (improving beamforming precision) within the same overall time budget, effectively decoupling the number of sectors from the total SLS duration.
3Measurement precision
If the SSW frame includes all necessary fields for comprehensive beamforming training, then the training accuracy is improved, but the frame length and transmission time increase
Solution Approach 1:
The patent extracts and removes redundant fields from the SSW frame structure. It takes out the Direction subfield (since direction can be inferred from whether the STA is performing ISS or RSS) and the SSW Feedback subfield (as feedback is transmitted separately in an SSW-FB frame). This extraction maintains beamforming training accuracy while significantly reducing frame length and transmission time.
Solution Approach 2:
The patent introduces a separate SSW-FB (Sector Sweep Feedback) frame as an intermediary mechanism to carry feedback information. Instead of embedding feedback directly in the SSW frame, the system uses a dedicated feedback frame transmitted afterward. This mediator approach allows the SSW frame to remain compact and fast while still preserving comprehensive beamforming training capability through the separate feedback channel.
Data Source
AI summary
A communication apparatus includes a PHY frame generating circuit that generates a PHY frame including either of a short Sector Sweep frame and a Sector Sweep frame; and an array antenna that selects, based on the PHY frame, any sector from among a plurality of sectors and transmits the PHY frame. In a case where, in the PHY frame including the short Sector Sweep frame, a Direction field of the short Sector Sweep frame indicates Initiator Sector Sweep, the PHY frame generating circuit replaces a Short Sector Sweep Feedback field indicating a number of a selected best short Sector Sweep with a Short Scrambled Basic Service Set ID field indicating an abbreviated address generated from an address of a destination communication apparatus.