OFDM Repetition Encoding for Flexible Receive Bandwidth
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Solution Overview
Problem
Data networks, particularly those using the G.hn standard, face challenges in providing high-speed services with strict quality of service requirements due to poor radio frequency propagation and interference in multiple dwelling units, limiting their ability to support applications like high-definition video streaming.
Innovation Solution
A repetition scheme is implemented in network devices to generate encoded payload blocks using repetition-encoded forward error correction (FEC) codewords, which are transmitted as orthogonal frequency-division multiplexing (OFDM) symbols across the entire frequency band, allowing nodes to receive and decode messages without knowing the specific bandwidth of other nodes, enabling broadcast messages to be exchanged efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wireless local area networks (WLANs) are used for in-home networking, then ease of installation is improved, but data transmission reliability deteriorates due to poor radio frequency propagation and interference
Solution Approach 1:
The patent replaces wireless radio frequency transmission with wired electrical signal transmission through existing home wiring infrastructure (power lines, telephone wires, coaxial cables). This substitution eliminates RF propagation issues and interference problems while maintaining ease of installation, as the wiring infrastructure already exists in homes.
Solution Approach 2:
The patent changes the transmission medium from electromagnetic waves in air (WLAN) to electrical signals through conductors (wired networking). This parameter change fundamentally improves reliability by utilizing the stable electrical properties of wired media compared to the unpredictable RF environment.
2Device complexity
If traditional media access schemes are used in G.hn networks, then network coordination is simplified, but bandwidth utilization efficiency deteriorates when nodes have different receive bandwidths
Solution Approach 1:
The patent segments the frequency band into multiple subbands and assigns different repetition factors to different subbands. This allows the system to handle nodes with different receive bandwidths efficiently by allocating more repetitions to subbands used by nodes with narrower bandwidths, thereby improving overall bandwidth utilization without significantly increasing coordination complexity.
Solution Approach 2:
The patent applies different repetition encoding parameters to different subbands based on local requirements. Nodes with limited bandwidth receive more repetitions in their usable subbands, while nodes with wider bandwidths can utilize subbands with fewer repetitions. This local differentiation optimizes bandwidth utilization efficiency while maintaining manageable network coordination.
Data Source
AI summary
A network device implements a repetition scheme to generate a repetition-encoded FEC codeword for a FEC codeword. The repetition-encoded FEC codeword includes a set of bit sequences concatenated together. The set of bit sequences corresponds to a set of OFDM symbols. In some embodiments, each bit sequence is formed by M replicas of the FEC codeword and an offset is applied to shift the bit sequence where the offset is different for each bit sequence. In one embodiment, a right cyclic shift is used to offset the bits in each symbol. Each shifted bit sequence is allocated into subcarriers of an OFDM symbol over a frequency range indicative of an operating frequency band of a domain to form the respective OFDM symbol. The set of OFDM symbols is transformed into a time domain signal for transmission.