Staggered Serial Bus Transmission for Latency Reduction
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Solution Overview
Problem
Mobile communication devices experience increased latency and packet drops due to concurrent activity of multiple devices on a shared serial bus, leading to degraded performance in high-priority and low-priority communication.
Innovation Solution
Implementing staggered transmission techniques on a serial bus, where devices alternate as transmitters during a single transaction, allowing data exchange in both directions before the datagram is completely transmitted, reducing the need for bus turnaround and arbitration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple devices are concurrently active on the serial bus, then communication functionality is enhanced, but latency increases and packet drops occur
Solution Approach 1:
The patent segments the concurrent communication into staggered time slots, allowing devices to transmit alternately rather than simultaneously. This segmentation of transmission opportunities resolves the conflict between supporting multiple active devices and maintaining low latency, as each device gets dedicated transmission windows without collision.
Solution Approach 2:
The patent implements dynamic transmission scheduling where devices can switch between transmitting and receiving roles based on current communication needs. This dynamic alternation allows the system to adapt to varying traffic patterns while maintaining efficient bus utilization and preventing latency accumulation.
2Adaptability or versatility
If multiple devices are concurrently active on the serial bus, then communication versatility is improved, but packet reliability deteriorates
Solution Approach 1:
By segmenting bus access into alternating transmission slots for different devices, the patent eliminates packet collisions that occur with concurrent transmission. This segmentation ensures that each packet is transmitted without interference, maintaining high reliability while still supporting multiple active devices through time-division multiplexing.
3Adaptability or versatility
If traditional bus turnaround is used for bidirectional communication, then protocol compatibility is maintained, but bus latency increases
Solution Approach 1:
The patent performs preliminary setup of bidirectional communication parameters before actual data transmission begins. By pre-configuring the staggered transmission schedule and alternating roles, the system avoids the need for repeated bus turnaround sequences during data exchange, significantly reducing latency while maintaining protocol compatibility.
Solution Approach 2:
The patent enables continuous bidirectional data exchange by eliminating idle bus turnaround periods. Devices continuously transmit and receive in alternating slots without stopping the data flow, maintaining uninterrupted useful action on the bus and minimizing latency compared to traditional turnaround-based approaches.
4Ease of operation
If bus arbitration is performed for each transaction, then fair resource allocation is achieved, but bandwidth utilization decreases
Solution Approach 1:
The patent implements periodic arbitration where devices are granted transmission rights in alternating cycles rather than arbitrating for every single transaction. This periodic approach maintains fair resource allocation over time while reducing the frequency of arbitration overhead, thereby improving overall bandwidth utilization.
Data Source
AI summary
Systems, methods, and apparatus for optimizing bus latency associated with a serial bus using staggered bidirectional transmission within a transaction or datagram are described. A method performed at a device coupled to a serial bus includes initiating a transaction between the first device and a second device to exchange a datagram with the second device in a first direction over the serial bus, and exchanging one or more bytes of data with the second device in a second direction over the serial bus before the datagram has been completely transmitted. The first device and the second device alternate as transmitters on the serial bus such that direction of data transmission is staggered on the serial bus. The serial bus may be operated in accordance with an I3C, RFFE, SPMI, or other protocol.