OFDM Frame Structure for Legacy Bandwidth Compatibility
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Solution Overview
Problem
Existing radio communications systems face challenges in achieving backward compatibility between new and legacy systems with different bandwidths, particularly in transitioning from lower signal bandwidth systems like IEEE 802.16e to higher bandwidth systems like IEEE 802.16m, while maintaining seamless operation and efficient resource allocation.
Innovation Solution
A frame format and signaling method that divides the higher bandwidth channel into sub-bands corresponding to the lower bandwidth system, allowing both legacy and new systems to communicate effectively, with guard bands and preamble sequences used to distinguish and allocate resources, ensuring backward compatibility and efficient bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a new higher bandwidth communications system (IEEE 802.16m) is designed, then data rates and bandwidth utilization are improved, but backward compatibility with legacy systems (IEEE 802.16e) deteriorates
Solution Approach 1:
The patent divides the wider bandwidth channel into multiple sub-bands, where each sub-band corresponds to the bandwidth of legacy systems. This segmentation allows legacy terminals to operate on individual sub-bands while new terminals can utilize the entire bandwidth, thereby maintaining backward compatibility while achieving higher data rates.
Solution Approach 2:
The patent embeds legacy system sub-bands within the broader new system bandwidth structure. Each legacy sub-band is nested within the overall channel bandwidth, allowing legacy terminals to function within their designated sub-bands while new terminals access the full spectrum, including guard bands and remaining resources.
2Quantity of substance
If the channel bandwidth is increased from 5 MHz to 15-20 MHz, then system capacity and data rates are improved, but compatibility with existing 5 MHz terminals deteriorates
Solution Approach 1:
The patent applies local quality by assigning different bandwidth characteristics to different frequency regions. Specific sub-bands are designated with qualities suitable for legacy terminals (5 MHz equivalent), while other regions provide enhanced bandwidth for new terminals. This localized differentiation ensures legacy compatibility in designated regions while enabling high performance elsewhere.
Solution Approach 2:
The patent creates a universal frame structure that serves multiple functions: it supports both legacy 5 MHz terminals and new 15-20 MHz terminals simultaneously. The same physical channel carries data for both system types through appropriate resource allocation and framing, making the system universally compatible across different terminal capabilities.
3Productivity
If guard bands are reduced or eliminated to increase usable bandwidth, then bandwidth utilization is improved, but interference between adjacent channels increases
Solution Approach 1:
The patent applies partial action by retaining guard bands only where necessary for legacy system compatibility and interference protection, while eliminating or reducing them in regions allocated exclusively to new systems. This selective application of guard bands optimizes bandwidth utilization while maintaining necessary protection where legacy terminals operate.
Data Source
AI summary
The technology provides a frame handler, a controller, and a frame structure design for a new radio communications system that provides backward compatibility with an existing or legacy radio communications system with lower signal bandwidth. Data to be transmitted to the new and legacy radio terminals is processed into a frame using a frame format that is compatible with both the new radio access technology system and the legacy radio access technology system so that both types of radio terminals may receive and extract data from the frame intended for each of those radio terminals. The format allows new and legacy radio terminal communications across the different bandwidths employed by the new and legacy systems.