Control Channel Start Position Signaling in Wireless Systems
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Solution Overview
Problem
In wireless communication systems, particularly in 3GPP LTE systems, there is a need for an efficient method to transmit and receive control channels, especially when data and control channels are multiplexed in the same subframe, requiring accurate start position information of the data channel to be provided by the base station to terminals, and this is challenging especially in scenarios where multiple base stations transmit data and control channels to the same terminal.
Innovation Solution
The method involves allocating a data channel to a radio resource, adding start position information into the payload of the control channel, and signaling this information. This includes defining a bit field for the start position information, inserting a CRC value based on a predefined mask, and using temporary IDs to ensure unique CRC values for each terminal, as well as applying different scrambling sequences based on the start position information. Additionally, the method configures an enhanced downlink physical control channel by allocating demodulation reference signals and setting search spaces for control channel elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If start position information is added into the payload of the control channel, then the terminal can accurately demodulate the data channel, but the control channel payload size increases
Solution Approach 1:
The patent embeds start position information within existing control channel structures by utilizing unused bit fields in the DCI payload. Specifically, it reuses bits that would otherwise be reserved or unused in the downlink control information format, nesting the new information within the existing control message without adding a separate transmission channel.
Solution Approach 2:
The patent changes the interpretation of existing payload parameters by redefining the function of specific bit fields. Instead of adding new bits, it repurposes existing bits to carry start position information, effectively changing what the payload parameters represent while maintaining the same transmission size.
2Reliability
If multiple terminals are supported with unique CRC values, then each terminal can correctly identify its control channel, but the complexity of CRC calculation and ID management increases
Solution Approach 1:
The patent performs preliminary actions by pre-calculating and storing CRC values for each terminal during system initialization or connection setup. This allows the base station to quickly retrieve and apply the appropriate CRC value when transmitting control channels, avoiding complex real-time calculations for each transmission.
Solution Approach 2:
Each terminal is assigned a unique identifier that it uses to self-verify control channel integrity. The terminal independently calculates CRC using its own ID and compares it with the received CRC value, enabling self-service verification without requiring complex centralized management of CRC values.
3Reliability
If scrambling sequences are applied based on start position information, then control channel robustness is improved, but the processing complexity at the transmitter and receiver increases
Solution Approach 1:
The patent generates and stores scrambling sequences in advance based on predetermined parameters including start position information. These pre-generated sequences are kept in memory buffers, allowing the transmitter to simply retrieve and apply the appropriate sequence without performing complex generation operations during each control channel transmission.
Solution Approach 2:
The patent changes the initialization parameters of standard scrambling sequences to embed start position information. By modifying the seed or initial state of well-known scrambling algorithms with the start position data, it achieves position-dependent scrambling without implementing entirely new scrambling mechanisms, thus balancing robustness with processing simplicity.
Data Source
AI summary
A method of transmitting and receiving a control channel in a wireless communication system is provided. A base station allocates a data channel to a radio resource, adds start position information of the data channel into a payload of a control channel, and performs signaling for indication information on the start position information added into the payload of the control channel to a terminal. Accordingly, the legacy system and the enhanced system can efficiently transmit a control channel.