Power Line Network Protocol Coexistence via SOF Delimiter Reservation
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Solution Overview
Problem
Existing network protocols, such as HomePlug 1.0, face challenges in achieving higher data rates and better quality of service (QoS) over AC power lines while coexisting with existing power line communication protocols, particularly in in-home and Internet-access communications.
Innovation Solution
A method is introduced where a second network protocol coexists with a first CSMA protocol by reserving time periods on the medium using start of frame (SOF) delimiters without end of frame (EOF) delimiters, allowing stations to communicate using either protocol, and utilizing contention control fields to manage channel access priority and prevent lower-priority stations from transmitting during reserved times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a new protocol is introduced to achieve higher data rates and better QoS, then data transmission performance is improved, but compatibility with existing protocols deteriorates
Solution Approach 1:
The patent makes the SOF delimiter universal by designing it to serve dual purposes: it functions as a standard frame delimiter in existing CSMA protocols while simultaneously serving as a medium reservation signal for the new protocol. This multi-functionality allows stations to interpret the same signal structure according to their protocol type, enabling both protocols to coexist on the same medium without requiring separate signal formats.
Solution Approach 2:
The SOF delimiter acts as an intermediary element that bridges the two protocols. By embedding specific bit patterns (such as the medium reservation indicator bits) within the SOF structure, the patent creates a common language that both CSMA and new protocol stations can understand, allowing them to coordinate their access to the medium through this shared signal structure.
2Productivity
If time periods are reserved using SOF without EOF delimiters, then medium access efficiency is improved, but protocol complexity increases
Solution Approach 1:
The patent extracts the EOF delimiter from the transmission structure when medium reservation is required. By omitting the EOF in reserved time periods, the new protocol extends the reservation duration without requiring additional delimiters, thereby improving medium access efficiency. Stations are designed to understand that an SOF without a subsequent EOF indicates a reserved period, simplifying the overall structure compared to using separate reservation signals.
Solution Approach 2:
The medium reservation is established in advance through the SOF delimiter itself, which contains bits indicating that the subsequent time period is reserved. This preliminary action allows stations to know beforehand when the medium will be occupied, enabling them to defer their transmissions appropriately without requiring complex real-time arbitration mechanisms.
3Reliability
If contention control fields are used to prevent lower-priority stations from transmitting, then QoS is improved, but channel access flexibility deteriorates
Solution Approach 1:
The patent applies different access rules to different priority levels locally. High-priority stations are granted permission to transmit and reserve medium by setting specific bits in the SOF delimiter, while lower-priority stations are instructed to defer. This local differentiation of access rights based on priority level ensures that QoS requirements are met for time-sensitive traffic while still allowing lower-priority traffic to access the medium when resources are available, thus maintaining overall channel access flexibility.
Data Source
AI summary
Methods of operating in a network in which a plurality of stations communicate over a shared medium and contend for access during a priority resolution period. At least some of the stations use a first CSMA network protocol having certain characteristics (e.g., some transmissions have a format that includes a start of frame delimiter (SOF), a payload, and an end of frame delimiter (EOF), wherein the SOF and EOF each contain sufficient information to permit a station receiving only one of the SOF and EOF to determine the start of a priority resolution period). And at least some stations use a second network protocol capable of coexisting with the first protocol, so that stations may communicate using either the first or second protocol. The second protocol may have various characteristics configured to achieve coexistence with the first protocol (e.g., transmissions that have a format that includes an SOF but not an EOF).