Subband Full Duplex Slot Format With Frequency-Domain Separation
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Solution Overview
Problem
Wireless communication systems face inefficiencies in bandwidth utilization due to half-duplex mode limitations, where devices can only perform either uplink or downlink communications within a slot, leading to underutilization of resources and interference issues due to the inability to handle simultaneous uplink and downlink transmissions.
Innovation Solution
The implementation of subband full duplex (SBFD) slot formats, where uplink and downlink resources are separated in the frequency domain, with time gaps inserted to facilitate transitions and account for propagation delays, allowing devices to perform both uplink and downlink communications within the same slot while minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If half-duplex mode is used where devices can only perform either uplink or downlink communications within a slot, then device complexity is reduced and ease of operation is improved, but bandwidth utilization deteriorates and resource efficiency is reduced
Solution Approach 1:
The frequency band is segmented into multiple subbands, with specific subbands allocated for uplink and downlink transmissions. This allows the system to divide the available spectrum into dedicated regions, enabling simultaneous uplink and downlink operations in different frequency portions while maintaining operational simplicity through clear resource separation.
Solution Approach 2:
The system transitions from time-division duplexing (TDD) to frequency-division duplexing (FDD) by utilizing the frequency dimension. Instead of alternating between uplink and downlink in different time slots, the patent allocates specific frequency subbands for each direction, allowing concurrent transmissions in the same time slot but different frequency regions, thereby improving bandwidth utilization.
2Device complexity
If half-duplex mode is used where devices can only perform either uplink or downlink communications within a slot, then interference management is simplified, but resource utilization deteriorates
Solution Approach 1:
The frequency spectrum is segmented into distinct uplink and downlink subbands, creating clear separation between transmission directions. This segmentation allows devices to operate in full-duplex mode with simplified interference management, as the dedicated frequency regions prevent self-interference while maximizing resource utilization through simultaneous bidirectional communications.
Solution Approach 2:
Guard bands or frequency separation act as intermediaries between uplink and downlink subbands, preventing interference between simultaneous transmissions. This intermediary frequency separation enables full-duplex operation without requiring complex interference cancellation mechanisms, thus reducing device complexity while improving resource utilization.
3Productivity
If subband full duplex slot formats with frequency-separated uplink and downlink resources are implemented, then bandwidth utilization is improved and resource efficiency is enhanced, but device complexity increases due to RF tuning requirements
Solution Approach 1:
Time gaps are inserted between uplink and downlink transmissions to allow preliminary RF tuning and frequency switching before the next transmission direction begins. This preliminary action enables devices to prepare their radio frequency circuits in advance, reducing the complexity of real-time frequency switching while maintaining the benefits of subband full duplex operation.
Solution Approach 2:
The system employs periodic time gaps at regular intervals between uplink and downlink transmissions. These periodic gaps provide consistent opportunities for RF tuning and frequency transitions, making the full-duplex operation more manageable and reducing device complexity through predictable, rhythmic switching patterns rather than continuous complex frequency management.
4Reliability
If time gaps are inserted between uplink and downlink resources to facilitate RF tuning, then device operability is improved and interference is reduced, but transmission time is increased and productivity is reduced
Solution Approach 1:
Time gaps are selectively inserted only where needed between uplink and downlink transmissions, rather than uniformly across all transmission intervals. This local application of time gaps ensures RF tuning opportunities are provided only when frequency transitions are required, minimizing unnecessary time losses while maintaining reliability where it is actually needed.
Solution Approach 2:
The system uses minimal time gaps - just enough to facilitate RF tuning and prevent interference - rather than excessive guard periods. This partial action approach provides sufficient time for frequency transitions while avoiding unnecessary transmission time losses, optimizing the balance between reliability and productivity.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A base station of a wireless communications system may transmit, to a user equipment (UE), a configuration message that indicates a transmission time interval (TTI) format for a plurality of TTIs. At least one format for the plurality of TTIs includes uplink resources and downlink resources separated in the frequency domain, which may be an example of a subband full duplex (SBFD) slot. Since the pattern may include some transitions between uplink and downlink resources, one or more gap periods (e.g., time gaps) may be positioned between such resources.