TDD User Equipment Shortened Cyclic Prefix Subframe Switching
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Solution Overview
Problem
Current wireless communication systems, such as 3GPP LTE, face challenges in efficiently managing uplink and downlink subframes, particularly in short-distance communications where propagation delay is low, leading to inefficiencies in resource utilization and timing advance command length.
Innovation Solution
A Time Division Duplex (TDD) transmission and reception method is implemented, where user equipment receives information about subframe configurations and applies a shortened Cyclic Prefix (CP) to optimize subframe switching, generate guard periods, and adjust timing advance commands, allowing for dynamic reconfiguration of uplink and downlink subframes and reducing the length of timing advance commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normal Cyclic Prefix (CP) length is used in TDD subframes, then protection against inter-subframe interference is ensured, but resource utilization efficiency decreases in short-distance communications where propagation delay is low
Solution Approach 1:
The patent applies a shortened Cyclic Prefix (CP) length specifically in TDD subframes where switching occurs between downlink and uplink, rather than using a fixed normal CP length across all subframes. This dynamic adaptation of CP length to the specific communication scenario (short-distance with low propagation delay) reduces wasted resources while maintaining sufficient protection against inter-subframe interference, thereby improving resource utilization efficiency without sacrificing reliability
Solution Approach 2:
The invention applies different CP lengths to different subframes based on local conditions: shortened CP is applied in subframes requiring switching between downlink and uplink in short-distance scenarios, while normal CP can be used in other subframes. This localized optimization ensures that the CP length matches the specific interference protection needs of each subframe, avoiding the resource waste associated with uniformly using normal CP length across all subframes
2Device complexity
If subframe configurations are fixed in 3GPP LTE, then system complexity is reduced, but adaptability to short-distance communications with low propagation delay is limited
Solution Approach 1:
The patent enables dynamic reconfiguration of TDD subframes by allowing the eNodeB to flexibly assign downlink and uplink subframes based on real-time communication conditions, including propagation delay characteristics. This dynamic subframe configuration allows the system to adapt to short-distance communications with low propagation delay by optimizing the timing and allocation of uplink and downlink subframes, thereby improving adaptability without requiring complete redesign of the subframe structure
Solution Approach 2:
The invention changes the timing parameters of TDD subframes by applying shortened CP length and adjusting the timing advance command bits, allowing the system to adapt to different propagation delay conditions. By modifying these timing parameters dynamically based on communication distance and propagation characteristics, the system achieves better adaptability to short-distance communications while maintaining a relatively simple configuration framework
3Measurement precision
If timing advance command uses full 11 bits, then precision in timing adjustment is maintained, but resource efficiency decreases in short-distance communications where propagation delay is low
Solution Approach 1:
The patent reduces the timing advance command from the standard 11 bits to fewer bits (e.g., 8 bits) specifically in short-distance communications where propagation delay is low. This parameter change is appropriate because the reduced timing range required in short-distance scenarios does not demand the full 11-bit precision, allowing the system to use fewer bits efficiently while maintaining sufficient timing adjustment precision for the specific communication distance, thereby improving resource efficiency
Data Source
AI summary
According to one embodiment of the present invention, suggested is a method for user equipment transceiving a time division duplex. The method comprises the steps of: receiving from a cell first information on a downlink (DL)-uplink (UL) subframe configuration according to the TDD; receiving second information on whether to apply a third cyclic prefix (CP), which has a reduced length compared to a first CP and a second CP; and depending on the first information, determining whether to apply the third CP to the downlink subframe and the uplink subframe according to the second information.