Virtual Control Resource Blocks for OFDM Downlink Interference Randomization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OFDM communication systems lack a simple and future-proof method for transmitting various types of control channels in the downlink, particularly in LTE systems, which complicates the handling of different control channel types and their coding rates, and does not effectively address inter-cell interference and frequency diversity.
Innovation Solution
The method involves mapping OFDM control channel symbols to virtual control resource blocks, which are then uniformly distributed across the transmission bandwidth using multiple transmit antennas, allowing for efficient multiplexing and frequency hopping, and organizing these blocks in a tree structure for interference randomization and reliable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control channels are transmitted using traditional mapping methods in OFDM downlink, then the transmission can be implemented, but the system complexity increases and future adaptability is limited
Solution Approach 1:
The patent segments control channel resources into virtual control resource blocks (VCRBs) that can be independently configured and mapped. Each VCRB represents a discrete unit that can be flexibly allocated across different subframes and frequency resources, enabling the system to adapt to varying control channel requirements without redesigning the entire mapping structure.
Solution Approach 2:
The patent creates a universal VCRB mapping framework that can handle multiple types of control channels (PDCCH, ePDCCH, etc.) through a single unified structure. The same VCRB mapping mechanism serves different control channel types, different numbers of user equipments, and different system bandwidths, eliminating the need for separate mapping procedures for each scenario.
2Reliability
If control channels are distributed across the bandwidth, then frequency diversity is improved, but inter-cell interference randomization becomes more challenging
Solution Approach 1:
The patent employs dynamic VCRB mapping where the specific resource block assignments and frequency positions can change from subframe to subframe based on scheduling decisions and interference conditions. This dynamic allocation allows the system to maximize frequency diversity in some subframes while applying interference coordination in others, adapting to changing radio conditions.
Solution Approach 2:
The patent changes key parameters such as VCRB size, number of VCRBs, and mapping patterns based on system conditions including bandwidth, number of user equipments, and interference measurements. By adjusting these parameters dynamically, the system optimizes both frequency diversity gain and interference randomization effectiveness for different operating scenarios.
3Adaptability or versatility
If multiple control channel types are transmitted simultaneously, then system functionality is enhanced, but the complexity of managing different coding rates and resource allocation increases
Solution Approach 1:
The patent merges the resource allocation and coding rate management of multiple control channel types into a unified VCRB framework. Different control channel types share the same VCRB structure, and resource allocation is performed in terms of VCRBs rather than separate resource units for each channel type. This consolidation simplifies the management complexity while maintaining support for diverse control channel functionalities.
Data Source
AI summary
In a method of transmitting control channel symbols in an OFDM communication system downlink in each sub-frame, the OFDM communication system including one or more transmit antennae, for each transmit antenna, each of the OFDM symbols of a control channel which are to be transmitted over the air is mapped to each of the corresponding non-punctured logical resource elements of one virtual control resource block VCRBp,k. For each transmit antenna, the logical resource elements in each virtual control resource block VCRBp,k are mapped to physical resource elements in each of the first L OFDM symbols so that the physical resource elements are uniformly spaced over the entire transmission bandwidth. For each transmit antenna, the physical resource elements are transmitted to user equipment.