Downlink Control Channel Capacity via Frequency Division Multiplexing
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Solution Overview
Problem
In next-generation radio communication systems, the increasing number of users poses a challenge for conventional radio resource allocation methods, which fail to adequately support Multiple User MIMO (MU-MIMO) transmission, leading to a lack of capacity in the downlink control channel.
Innovation Solution
The proposed solution involves frequency-division multiplexing of downlink control signals and data signals into radio resources after a predetermined number of OFDM symbols in a subframe, allowing for enhanced PDCCH (Physical Downlink Control Channel) extension into the PDSCH (Physical Downlink Shared Channel) region, and dynamic allocation of radio resources for retransmission response signals using identification information and indices like CCE or VRB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional radio resource allocation methods are used, then the system structure is simple, but the downlink control channel capacity is insufficient to support increased number of users
Solution Approach 1:
The patent extends the PDCCH region from the time domain only (first N OFDM symbols) into the frequency domain by allowing PDCCH to occupy resource blocks in the PDSCH region. This dimensional extension provides additional control channel capacity without fundamentally changing the LTE frame structure, enabling support for more users while maintaining backward compatibility.
Solution Approach 2:
The patent segments the downlink radio resources into distinct regions: a first region for PDCCH in the time domain (first N OFDM symbols) and a second region for extended PDCCH in the frequency domain (resource blocks in PDSCH region). This segmentation allows independent optimization and allocation of control channel resources to meet increased user demands.
2Quantity of substance
If downlink control signals are multiplexed only in the time domain (first N OFDM symbols), then the control channel structure is simple, but the control channel capacity is limited
Solution Approach 1:
The patent transitions from one-dimensional time-domain multiplexing to two-dimensional time-frequency multiplexing by allowing PDCCH to be allocated in both the time domain (first N OFDM symbols) and frequency domain (resource blocks in PDSCH region). This dimensional change doubles the available multiplexing dimensions, significantly increasing control channel capacity.
3Productivity
If frequency division multiplexing is applied to downlink control signals and data signals, then resource usage efficiency improves, but the system complexity increases
Solution Approach 1:
The patent segments downlink resources into control regions (PDCCH) and data regions (PDSCH) with clear boundaries in both time and frequency domains. This segmentation enables efficient frequency division multiplexing where control and data signals occupy different resource blocks, improving resource usage efficiency while maintaining manageable system complexity through structured resource allocation.
Data Source
AI summary
To provide a user terminal, radio base station apparatus, radio communication system and radio communication method that support increases in the number of users, a user terminal is provided with a reception section that receives a downlink control signal multiplexed into radio resources from the starting OFDM symbol to a predetermined OFDM symbol in a subframe, and a downlink control signal subjected to frequency division multiplexing with a downlink data signal into radio resources after the predetermined OFDM symbol, a retransmission check section that performs a retransmission check on the downlink data signal based on the downlink control signal subjected to frequency division multiplexing to output a retransmission response signal, and a selection section that selects a radio resource of an uplink control channel used in transmission of the retransmission response signal.