SC-FDMA Control Information Transmission Using Orthogonal Codes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In mobile communication systems, particularly in LTE, there is a challenge in efficiently transmitting a large quantity of control information due to insufficient resources in the time, frequency, and code domains, especially when the quantity of control information exceeds the capacity of existing transmission schemes like 'type A' and 'type B' schemes.
Innovation Solution
A new transmission scheme, referred to as 'type C', which allocates a separate frequency band for control information and spreads it in the time domain using orthogonal codes, such as Walsh codes or Orthogonal Variable Spreading Factor (OVSF) codes, allowing for increased transmission bit rate by mapping multiple control information modulation symbols per sub-frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If type A transmission scheme is used to transmit control information through a pre-defined frequency band, then the transmission structure is simple and resource allocation is straightforward, but the transmission bit rate is limited and cannot handle large quantities of control information
Solution Approach 1:
The patent introduces a new dimension for control information transmission by mapping multiple modulation symbols to each resource element in the time-frequency grid. Instead of transmitting one symbol per resource element as in type A, the invention maps multiple control information modulation symbols to each resource element, thereby increasing the transmission bit rate without adding more resource elements. This dimensional change in symbol mapping enables higher throughput while maintaining the existing resource allocation structure.
Solution Approach 2:
The patent segments control information into multiple modulation symbols that are then mapped to resource elements. By dividing the control information stream into multiple symbols and distributing them across the allocated resource elements, the system can transmit larger quantities of control information efficiently. This segmentation approach allows the transmission scheme to handle variable amounts of control information flexibly.
2Quantity of substance
If more resource elements are allocated to transmit control information, then the transmission capacity increases, but the resource utilization efficiency decreases and available resources for data transmission are reduced
Solution Approach 1:
The patent merges multiple control information modulation symbols into a single resource element by mapping them together. This combining approach allows multiple symbols to be transmitted through the same time-frequency resource, effectively increasing the quantity of control information transmitted without requiring additional resource elements. The merging of multiple symbols into one resource element maintains resource utilization efficiency while achieving higher transmission capacity.
3Reliability
If frequency hopping is employed to increase frequency diversity, then the robustness against interference improves, but the system complexity and overhead increase
Solution Approach 1:
The patent implements dynamic resource element allocation and symbol mapping that adapts to channel conditions. The system can dynamically adjust the mapping of control information symbols to resource elements based on current channel quality and interference conditions. This dynamic approach provides frequency diversity and robustness against interference without requiring complex frequency hopping schemes, as the flexibility is achieved through adaptive symbol mapping within the allocated resources.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided is a method and an apparatus for transmitting a large quantity of control information in a mobile communication system. When there is no uplink data to be transmitted, a UE spreads second control information, a quantity of which is less than or equal to a pre-defined threshold, by using a ZC sequence cyclic-shifted according to resource blocks, each of which indicates at least one time interval used for a transmission of the second control information. When there is uplink data to be transmitted, the UE performs TDM of the uplink data with third control information. When there is no uplink data to be transmitted and the quantity of control information exceeds a pre-defined threshold, or when the first control information includes various types of information, the UE spreads the first control information in a time domain by the orthogonal codes.