Base Station Pilot Sequence Multiplexing for Channel Estimation
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Solution Overview
Problem
In radio communication systems, the accuracy of channel estimation degrades when unicast and multicast data are time-multiplexed, leading to poor error rate performance due to interpolation errors between subframes with different pilots.
Innovation Solution
A base station configuration that generates a combined pilot sequence for both unicast and multicast subframes, allowing for improved interpolation accuracy by time-multiplexing these pilots, enabling accurate channel estimation across subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different pilots are used for unicast and multicast subframes, then channel estimation can be performed separately for each type, but interpolation accuracy between subframes degrades
Solution Approach 1:
The patent merges the pilot sequences for unicast and multicast subframes by generating a combined pilot sequence that is reused across both subframe types. This allows the mobile station to perform channel estimation using the same pilot reference, enabling accurate interpolation between subframes while maintaining separate data multiplexing. The combined pilot sequence is generated once and applied to both unicast and multicast subframes, resolving the contradiction between separate estimation and interpolation accuracy.
2Productivity
If pilots are time-multiplexed at subframe boundaries, then unicast and multicast data can be transmitted efficiently, but channel estimation accuracy degrades at subframe transitions
Solution Approach 1:
The patent applies preliminary action by generating and positioning the combined pilot sequence at specific locations within each subframe before data transmission begins. The pilots are placed in predetermined resource elements that are consistent across unicast and multicast subframes, allowing the mobile station to perform channel estimation before data reception and maintain accurate interpolation across subframe boundaries. This preliminary positioning of pilots ensures continuous channel knowledge despite subframe transitions.
3Adaptability or versatility
If separate pilot sequences are used for unicast and multicast, then channel-specific estimation is possible, but system complexity increases
Solution Approach 1:
The patent applies universality by creating a single combined pilot sequence that serves multiple functions: it provides channel estimation reference for both unicast and multicast subframes, enables interpolation across subframe boundaries, and maintains compatibility with existing OFDM processing. This universal pilot approach eliminates the need to manage separate pilot sequences while preserving the ability to perform type-specific channel estimation through selective pilot usage.
Data Source
AI summary
A base station realizing enhancement of the interpolation accuracy of the channel estimate between sub-frames. In a base station (100), a scrambling section (105) carries out scrambling such that a predetermined pilot signal sequence is multiplied by a scrambling sequence containing both a sequence unique to the base station (100) and different with cells and a sequence common to base stations for each chip and generates a pilot sequence containing both a pilot for unicast sub-frame and a pilot for multicast sub-frame, a multiplexing section (106) for time-multiplexing the pilot sequence, the unicast data symbol, and a multicast data symbol for each sub-frame, and an S/P section (107) converts the pilot sequences, the unicast data symbols, and the multicast data symbols sequential serially inputted from the multiplexing section (106) the numbers of which are equal to the number of subcarries included in one OFDM symbol into parallel ones and outputs them to an IFFT section (108).