Base Station Control Channel Center Frequency Raster Alignment
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Solution Overview
Problem
In OFDM-based wireless communication systems, mobile stations face complexity in connecting to a downlink signal when using frequency bands other than the predetermined raster, especially when switching between wide and narrow bands like 20 MHz and 5 MHz, due to non-integral sub-carrier spacing and raster intervals.
Innovation Solution
The base station transmits a synchronization channel and control channel using a band with a center frequency on a raster, including center frequency information for the mobile station, allowing it to connect to the desired band without searching off-raster frequencies, and uses two-dimensional scrambling codes to ensure seamless demodulation across different bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mobile station searches for center frequency by checking each frequency raster in series, then the mobile station can specify the center frequency and connect to downlink, but the connection process becomes complicated when using multiple frequency bands with non-integral sub-carrier spacing
Solution Approach 1:
The base station transmits control information in advance that includes center frequency information for multiple frequency bands. This preliminary transmission of frequency configuration data allows the mobile station to directly obtain the required frequency parameters without performing complex sequential searches across multiple rasters, thereby simplifying the connection process while maintaining support for multiple bands.
2Adaptability or versatility
If the system supports multiple frequency bands with different bandwidths, then the system flexibility and adaptability improve, but the frequency search and connection process becomes more complicated
Solution Approach 1:
The control information transmitted by the base station serves multiple functions simultaneously: it provides center frequency information for both the current frequency band and other available frequency bands. This universal control mechanism allows the mobile station to access frequency configuration data for multiple bands through a single information source, maintaining system flexibility while avoiding the need for separate search procedures for each band.
3Adaptability or versatility
If the center frequency of a narrow band is not positioned on a frequency raster, then the frequency band can be flexibly allocated, but the mobile station cannot easily connect to the downlink signal
Solution Approach 1:
The control information acts as an intermediary that bridges the gap between flexible frequency allocation and ease of connection. It contains pre-calculated center frequency information for bands with non-raster frequencies, allowing the mobile station to directly obtain the correct frequency parameters without attempting to align with standard rasters. This intermediary information enables both flexible frequency usage and simple connection procedures to coexist.
Data Source
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AI summary
A base station apparatus performing communication in a communication system in which a plurality of types of bandwidths are defined comprises a transmission unit and a multiplexing unit. The transmission unit is configured to transmit transmission data by using a bandwidth of the plurality of types of bandwidths in a band centered on a predetermined center frequency. The multiplexing unit is configured to multiplex a control channel into a center band of a predetermined width including the center frequency of the band used in the transmission unit irrespective of the bandwidth used in the transmission unit.