TDM Switch Latency Reduction in Distributed Wireless Baseband Systems
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Solution Overview
Problem
In distributed Wi-Fi networks, existing technologies face challenges in achieving low latency for data transmission between radio heads and central controllers, particularly due to the introduction of extra latency from Ethernet frame processing and CRC verification, which affects compliance with the 802.11 standard and client device performance.
Innovation Solution
The implementation of an uplink time-division multiplexing (TDM) switch system that receives and processes TDM cells from radio heads, forwarding data bits with predetermined destinations through Ethernet links between central controllers to reduce latency, utilizing TDM cells instead of Ethernet frames to minimize processing overhead and optimize data transmission paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Ethernet frame processing is used for data transmission between radio heads and central controllers, then standard network compatibility is achieved, but latency increases and 802.11 compliance is compromised
Solution Approach 1:
The patent segments the data transmission process by dividing the TDM data stream into fixed-size cells with predetermined destinations. Each cell is independently routed through the switch fabric, enabling parallel processing and reducing overall latency while maintaining compatibility with standard network infrastructure through Ethernet link integration.
Solution Approach 2:
The patent implements preliminary action by pre-configuring destination information in each TDM cell before switching. The switch uses this pre-loaded destination data to make immediate forwarding decisions without requiring frame processing or CRC verification, thereby eliminating the latency associated with standard Ethernet frame handling while maintaining network compatibility.
2Reliability
If Ethernet frames with CRC verification are used, then data integrity checking is performed, but processing overhead increases and latency worsens
Solution Approach 1:
The patent extracts the data integrity function from the Ethernet frame processing layer and implements it at the TDM cell level through predetermined destination routing. By removing the need for CRC verification and frame parsing, the system eliminates processing overhead while maintaining reliability through the inherent structure of TDM cells that include destination identification information.
Solution Approach 2:
The patent introduces TDM cells as an intermediary data structure between the radio heads and central controllers. These cells carry both data and destination information in a compact format that eliminates the need for Ethernet frame processing and CRC verification, thereby reducing processing overhead while maintaining data integrity through deterministic routing.
3Loss of time
If TDM cells with predetermined destinations are used instead of Ethernet frames, then latency is reduced and bandwidth is optimized, but network processing complexity changes
Solution Approach 1:
The patent applies preliminary action by pre-configuring destination information in each TDM cell before it enters the switch. This allows the switch to perform simple table-lookup forwarding based on predetermined destination data, reducing switching complexity despite the specialized TDM cell format. The complexity is shifted to the cell generation stage rather than the switching stage.
Data Source
AI summary
The present disclosure discloses a distributed system. The distributed system includes a plurality of radio heads and a plurality of controllers disposed in one or more chassis external to the plurality of radio heads. Each of the plurality of controllers includes a baseband unit (BBU), an uplink time-division multiplexing (TDM) switch and a downlink TDM switch. The uplink TDM switch and the downlink TDM switch forward data bits between a radio head and a BBU by using TDM cells which may reduce latency relative to using Ethernet frames.