TDD Frame Structure with Variable Cyclic Prefix Lengths
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Solution Overview
Problem
The existing IEEE 802.16 wireless communication systems face interference issues due to different cyclic prefix lengths in time division duplexing (TDD) frame structures across adjacent cells, and there is a need for a frame structure that supports both time division duplexing (TDD) and frequency division duplexing (FDD) schemes while maintaining backward compatibility.
Innovation Solution
A method and structure for TDD frames with varying cyclic prefix lengths and an FDD frame structure that shares common features with TDD frames, allowing for efficient coexistence and minimizing interference, including specific configurations for different downlink-to-uplink ratios and cyclic prefix lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If TDD frames with different cyclic prefix lengths are used in adjacent cells, then system flexibility and adaptability are improved, but interference between frames occurs due to boundary overlap between downlink and uplink regions
Solution Approach 1:
The patent applies local quality by configuring different cyclic prefix lengths in different subframes within the same frame structure. Specifically, the first through fourth subframes use a first cyclic prefix length while the fifth through eighth subframes use a second cyclic prefix length. This localized differentiation allows each subframe to be optimized for its specific function while maintaining overall frame synchronization, thereby preventing boundary overlap interference between adjacent cells.
Solution Approach 2:
The patent segments the TDD frame into multiple subframes with different cyclic prefix length configurations. By dividing the frame into distinct segments (first-fourth subframes and fifth-eighth subframes) with different CP lengths, the system can independently control the timing and duration of each segment, ensuring that downlink and uplink boundaries align properly across adjacent cells and preventing interference.
2Adaptability or versatility
If a frame structure supports both TDD and FDD schemes, then system versatility is improved, but device complexity increases due to multiple configuration requirements
Solution Approach 1:
The patent implements universality by designing a frame structure that can operate in both TDD and FDD modes using the same basic framework. The frame consists of eight subframes with configurable cyclic prefix lengths that can accommodate different duplexing schemes. This multi-functional design allows the system to support both TDD and FDD without requiring separate frame structures, thereby reducing overall device complexity while maintaining versatility.
Solution Approach 2:
The patent applies dynamics by enabling flexible configuration of cyclic prefix lengths in different subframes based on the operating mode. In TDD mode, specific subframes can have different CP lengths to optimize for TDD requirements, while in FDD mode, the same frame structure can be configured differently. This dynamic configurability allows a single frame structure to adapt to multiple modes without increasing inherent complexity.
Data Source
AI summary
A device and method for communicating by a mobile communication terminal in communication with a base station. The method according to an embodiment includes exchanging a frame of data with the base station. The frame of data includes a) a plurality of first subframes each having a first number of orthogonal frequency division multiple access (OFDMA) symbols, and b) a plurality of second subframes each having a second number of orthogonal frequency division multiple access (OFDMA) symbols different from the first number. A first and a last subframe each includes one of the plurality of first subframes.