802.16m TDD Frame Structure for Legacy Compatibility
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Solution Overview
Problem
The current IEEE 802.16m system lacks a defined frame structure for the 8.75 MHz system band, preventing backward compatibility with legacy systems that use this bandwidth.
Innovation Solution
A method and apparatus are developed to design a 802.16m frame structure that is backward-compatible with legacy systems by transmitting and receiving signals using a time division duplexing frame structure, specifically using 15 OFDMA symbols in the uplink frame, divided into subframes of 9 and 6 OFDMA symbols, to support both legacy and 802.16m systems operating in the 8.75 MHz bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a frame structure is defined for 8.75 MHz system band in 802.16m, then backward compatibility with legacy systems is achieved, but system complexity increases due to supporting multiple frame structures
Solution Approach 1:
The patent applies universality by designing a frame structure that serves multiple purposes: it is compatible with both legacy 8.75 MHz systems and new 802.16m systems. The frame structure can function as a TDD frame for legacy systems while also supporting FDD operations and 16m-only modes, allowing one structure to fulfill multiple system requirements without needing entirely separate designs.
Solution Approach 2:
The frame structure is segmented into distinct operational modes and configurations. It includes separate frame types for TDD and FDD operations, with specific subframe structures that can be independently configured. This segmentation allows the system to switch between legacy-compatible mode and 16m-enhanced mode by activating different segments of the overall frame structure design.
2Adaptability or versatility
If uplink transmission timing is aligned for legacy systems, then compatibility is maintained, but flexibility in resource allocation is reduced
Solution Approach 1:
The patent implements dynamics by making the frame structure configurable and adaptable based on operational mode. The same frame structure can dynamically adjust its parameters - such as subframe lengths, symbol allocations, and timing configurations - to match either legacy system requirements or 16m performance optimizations. This dynamic configurability allows the system to maintain compatibility when needed while achieving higher productivity when operating in 16m-only mode.
Solution Approach 2:
The invention utilizes parameter changes by defining multiple sets of frame structure parameters that can be activated based on the operational mode. Key parameters such as frame length, subframe boundaries, and symbol timing can be changed between legacy-compatible values and 16m-optimized values. This allows the system to preserve compatibility through parameter adjustment rather than structural redesign, maintaining resource allocation flexibility.
Data Source
AI summary
The present invention relates to transmission and reception of a frame for a legacy support mode of IEEE 802.16m system for supporting a legacy system. A method of transmitting an uplink signal, in which a signal is transmitted by a user equipment in a wireless mobile communication system, according to the present invention includes the step of transmitting the signal from the user equipment, wherein the signal is transmitted via an uplink frame including 15 OFDMA (orthogonal frequency division multiple access) symbols and wherein the uplink frame comprises a first uplink subframe including 9 OFDMA symbols and a second uplink subframe including 6 OFDMA symbols. Preferably, the user equipment is multiplexed with a second user equipment supporting a legacy system for the wireless mobile communication system only by FDM for an uplink.