Partial Subframe Control Channel Transmission in Unlicensed Bands
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Solution Overview
Problem
The challenge in wireless communication systems is to efficiently transmit signals in unlicensed frequency bands while ensuring communication quality and preventing interference with conventional wireless devices, particularly in cellular communication services where the unlicensed band is shared without exclusive frequency use rights.
Innovation Solution
A method and apparatus for transmitting a radio frame divided into subframes, where a partial subframe with a duration shorter than the standard subframe is used to start transmitting a control channel at an Orthogonal Frequency Division Multiplexing (OFDM) symbol position, allowing for efficient scheduling of data and channel state estimation, and the control channel schedules only data transmitted later, with the option to transmit or receive at OFDM symbol positions other than the subframe boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the unlicensed band is used for cellular communication service, then spectrum shortage problem is solved, but communication quality cannot be guaranteed and interference with conventional wireless devices occurs
Solution Approach 1:
The patent segments the subframe into multiple slots, each containing multiple OFDM symbols. This segmentation allows flexible allocation of resources within the subframe, enabling the system to adapt to different transmission requirements while maintaining coexistence with conventional devices through controlled access patterns in the unlicensed band.
Solution Approach 2:
The patent implements dynamic transmission timing where the base station can transmit control channels at flexible OFDM symbol positions within slots rather than being constrained to fixed subframe boundaries. This dynamic approach allows the system to adjust transmission timing to avoid interference with conventional wireless devices while maintaining communication quality.
2Productivity
If multiple communication facilities use the unlicensed band simultaneously, then spectrum efficiency improves, but interference between devices increases
Solution Approach 1:
The patent employs a listen-before-talk mechanism where the base station performs clear channel assessment before transmitting. This preliminary action ensures that the unlicensed band is free from interfering signals from conventional wireless devices before the base station begins transmission, enabling multiple facilities to share the spectrum efficiently without causing harmful interference.
Solution Approach 2:
The patent incorporates feedback mechanisms where the base station monitors the transmission environment and adjusts its transmission timing and power levels accordingly. This feedback allows the system to respond to changes in the spectral environment, maintaining spectrum efficiency while minimizing interference with other communication facilities.
3Ease of operation
If control channel is transmitted at traditional subframe boundary, then scheduling simplicity is maintained, but transmission efficiency in unlicensed band is reduced
Solution Approach 1:
The patent transitions from static subframe boundary scheduling to dynamic scheduling within slots. The control channel can be transmitted at various OFDM symbol positions within a slot, allowing the base station to optimize transmission timing based on real-time conditions in the unlicensed band while maintaining relatively simple scheduling through the slot-based structure.
Solution Approach 2:
By dividing the subframe into slots with multiple OFDM symbols, the patent creates a finer-grained scheduling unit. This segmentation allows more flexible and efficient transmission timing in the unlicensed band while maintaining scheduling simplicity through the structured slot-based approach, improving overall transmission efficiency.
Data Source
AI summary
A base station of a wireless communication system is disclosed. The base station comprise a communication module; and a processor. The processor is configured to transmit a radio frame divided into a plurality of subframes by using the communication module, wherein a duration of each of the plurality of subframes is 1 ms. When the base station transmits a partial subframe having a duration shorter than the duration of each of the plurality of subframes, the processor starts to transmit a control channel for scheduling data transmitted through the partial subframe at a symbol position for transmitting a reference signal.