Extended PDCCH Resource Allocation in LTE Control Channels
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Solution Overview
Problem
In LTE wireless communication networks, the limited resources and coding gains in the control channel lead to unreliable decoding of Downlink Control Information (DCI) by mobile terminals, resulting in data reception failures and misallocated resource issues, especially in conditions with high Block Error Rate (BLER).
Innovation Solution
The base station dynamically determines when the control portion has insufficient resources and temporarily transmits control information in the data portion, using a higher coding gain, and defines an Extended PDCCH (E-PDCCH) within the PDSCH to ensure reliable reception, by shifting control information from the PDCCH to the PDSCH for selected mobile terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control information is transmitted in the control portion (PDCCH) with limited resources, then the control channel structure is maintained and simple decoding is possible, but the coding gain is insufficient leading to high BLER and unreliable decoding
Solution Approach 1:
The patent extends the control channel into the data portion of the sub-frame, utilizing previously unused time-frequency resources. By defining an Extended PDCCH (E-PDCCH) that spans both the control and data portions, the invention effectively adds a new dimension for control information transmission, increasing available resources without expanding the traditional control channel structure.
Solution Approach 2:
The data portion of the sub-frame is given dual functionality: it serves both as a data channel (PDSCH) and as an extended control channel (E-PDCCH). This multi-functionality allows the same time-frequency resources to carry both control and data information, resolving the contradiction between maintaining simple control channel structure and providing sufficient resources for reliable decoding.
2Productivity
If more control information is transmitted in the control portion, then more mobile terminals can be scheduled, but the coding rate increases reducing decoding performance and increasing BLER
Solution Approach 1:
The control information transmission is segmented across two distinct regions: the traditional control portion (PDCCH) and the extended data portion (E-PDCCH). This segmentation allows control information for multiple mobile terminals to be distributed across different regions, each with appropriate coding rates, thereby maintaining both high productivity and reliability.
Solution Approach 2:
The invention changes the coding rate parameter by transmitting control information in the data portion where higher coding gains can be applied. The E-PDCCH utilizes the full sub-frame duration, enabling lower coding rates and improved decoding performance while still supporting multiple mobile terminals through efficient resource utilization.
3Reliability
If control information is transmitted in the data portion (PDSCH), then higher coding gains can be achieved improving reliability, but the device complexity increases due to extended PDCCH definition and resource management
Solution Approach 1:
The invention introduces dynamic control information transmission where the base station can flexibly allocate control information to either the PDCCH or E-PDCCH based on channel conditions and traffic requirements. This dynamic approach allows the system to adapt to varying reliability requirements while managing complexity through condition-based decision-making rather than fixed complex structures.
Solution Approach 2:
The patent introduces an intermediary layer of control information structure that bridges the traditional control channel and data channel. The E-PDCCH acts as an intermediary that maintains the control-information semantics and processing while utilizing data channel resources, thereby achieving higher reliability without requiring complete redesign of control and data processing architectures.
4Quantity of substance
If the control portion is extended to provide more resources, then more control information can be transmitted, but the time available for data transmission decreases reducing overall system throughput
Solution Approach 1:
The invention implements periodic control information transmission where control information can be sent in both the control portion and data portion of sub-frames. This periodic action across different sub-frame regions ensures that control information is reliably delivered without permanently reducing data transmission opportunities, as the E-PDCCH is activated only when needed.
Data Source
AI summary
A base station includes transmitter and associated processing circuits. The transmitter circuits are configured to transmit control information and data traffic to mobile terminals in repeating transmission intervals, each interval having defined control and data portions. The processing circuits are configured to dynamically determine that the control portion has insufficient resources for transmitting control information to one or more of the mobile terminals, and, in response, at least temporarily transmit control information in the data portion, rather than in the control portion, for a selected one or more of the mobile terminals. Correspondingly, a mobile terminal is configured to selectively search for and decode control information in the data portion of one or more transmission intervals, rather than in the control portion.