SBFD Random Access Using Subband RA-RNTI Mapping
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Solution Overview
Problem
TDD systems in wireless mobile communication face challenges with reduced coverage, increased latency, and reduced capacity due to limited uplink time duration, which can be addressed by implementing sub-band full duplex (SBFD) to enable simultaneous downlink and uplink operations.
Innovation Solution
A method and apparatus support sub-band full duplex by configuring terminals to receive system information, initiate a random access procedure, transmit preambles on specific radio resource occasions, and monitor PDCCH using specific RA-RNTIs, allowing for simultaneous downlink and uplink operations on separate sub-bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TDD time domain resource is split between downlink and uplink, then downlink and uplink can be separated in time, but uplink coverage is reduced, latency increases and capacity is reduced
Solution Approach 1:
The patent segments the frequency band into multiple subbands, allowing different subbands to be used for different purposes (downlink, uplink, or simultaneous full duplex). This segmentation enables the system to allocate specific subbands for uplink transmission while others remain available for downlink, thereby increasing uplink capacity without completely sacrificing downlink performance.
Solution Approach 2:
The patent transitions from time-division multiplexing (TDD) to frequency-division multiplexing by introducing subband full duplex operation. Instead of separating uplink and downlink only in the time domain, the system now utilizes the frequency dimension by allocating different subbands for different directions, effectively adding a spatial/frequency dimension to the resource allocation.
2Productivity
If TDD time domain resource is split between downlink and uplink, then downlink and uplink can be separated in time, but uplink coverage is reduced
Solution Approach 1:
By segmenting the frequency spectrum into subbands, the patent allows uplink transmission to occur simultaneously with downlink in different subbands. This frequency segmentation enables uplink coverage extension without requiring extended time durations, as uplink signals can be transmitted in dedicated uplink subbands during periods when other subbands handle downlink traffic.
Solution Approach 2:
The patent exploits the frequency dimension to overcome time duration limitations. By allocating specific subbands for uplink transmission, the system effectively creates additional uplink opportunities in the frequency domain, thereby extending uplink coverage without being constrained by the limited time slots available in traditional TDD configurations.
3Productivity
If TDD time domain resource is split between downlink and uplink, then downlink and uplink can be separated in time, but latency increases
Solution Approach 1:
The patent divides the frequency band into multiple subbands with different functional assignments. Uplink subbands are specifically designated for uplink transmission, allowing uplink data to be transmitted immediately when data arrives at the terminal, rather than waiting for the next uplink time slot. This segmentation eliminates uplink latency while maintaining overall system capacity through parallel downlink operations in other subbands.
Solution Approach 2:
By utilizing the frequency dimension for resource allocation, the patent enables simultaneous uplink and downlink operations in different subbands. This dimensional transition from pure time-division to frequency-division with full duplex capability allows uplink transmission to occur without time delays, as uplink subbands are continuously available for uplink traffic.
4Adaptability or versatility
If subband full duplex is implemented with separate RA-RNTI sets for different ROs, then random access can be supported in SBFD mode, but device complexity increases
Solution Approach 1:
The patent segments the random access resources by introducing separate RA-RNTI sets for different RO types (first RO for normal uplink, second RO for SBFD uplink). This segmentation allows the terminal to clearly distinguish between different random access opportunities and apply the appropriate RA-RNTI set, thereby supporting SBFD random access while maintaining manageable complexity through structured resource separation.
Solution Approach 2:
The patent adds a frequency dimension distinction to random access resources by defining different ROs in different subbands with corresponding RA-RNTI sets. This dimensional separation enables the system to support both traditional and SBFD random access modes simultaneously, providing adaptability while the structured approach to resource organization keeps terminal complexity within acceptable bounds.
Data Source
AI summary
A method and apparatus to support sub-band full duplex is provided. In the method, the terminal receives from a base station a system information; the terminal triggers a random access procedure; the terminal transmits a preamble on a first RO or on a second RO; the terminal monitors a PDCCH based on a specific RA-RNTI during a specific duration; and the terminal receives RAR based on the PDCCH. The specific RA-RNTI is selected from a first set of RA-RNTIs in case that the PRACH preamble is transmitted in the first RO and a second set of RA-RNTIs in case that the PRACH preamble is transmitted in the second RO.