MIMO Pilot Signal Allocation for HRPD Channel Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current High Rate Packet Data (HRPD) systems are insufficient for supporting wideband data transmission and efficient frequency resource use, particularly in next-generation systems like broadcasting services, due to limitations in data modulation schemes and antenna usage.
Innovation Solution
The implementation of a transmission/reception apparatus and method that supports Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies by allocating pilot signals in specific interlaces within the HRPD system, allowing for efficient data transmission and channel estimation using multiple antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HRPD system uses single carrier modulation scheme, then system complexity is low, but frequency selective multi-path fading resistance is weak
Solution Approach 1:
The patent divides the data transmission into multiple sub-carriers (e.g., 128 sub-carriers) that are orthogonal to each other. Each sub-carrier transmits a portion of the data independently, allowing the system to resist frequency selective fading by distributing the data across multiple frequency components rather than relying on a single carrier signal.
Solution Approach 2:
The patent transitions from single-carrier modulation to multi-carrier OFDM modulation, adding the frequency dimension to the transmission. By modulating data across multiple orthogonal sub-carriers in the frequency domain, the system gains robustness against frequency selective fading while maintaining manageable complexity through efficient FFT/IFFT processing.
2Productivity
If HRPD system uses conventional slot structure with TDM/CDM, then backward compatibility is maintained, but wideband data transmission capability is insufficient
Solution Approach 1:
The patent merges OFDM multi-carrier modulation with the existing HRPD TDM/CDM slot structure. The slot structure is extended to accommodate both traditional EV-DO users and new OFDM users by multiplexing different modulation schemes within the same time slot, enabling wideband data transmission while maintaining backward compatibility.
Solution Approach 2:
The patent creates a universal HRPD system that can support multiple transmission modes (EV-DO single-carrier, OFDM multi-carrier, and MIMO-OFDM) within the same network infrastructure. The base station can dynamically select the appropriate modulation scheme based on user capabilities, making the system adaptable to both wideband data transmission requirements and existing device limitations.
3Productivity
If HRPD system does not support MIMO technology, then device complexity is low, but frequency resource utilization efficiency is insufficient
Solution Approach 1:
The patent incorporates dedicated pilot signals at predetermined positions in the time-frequency grid before data transmission begins. These pilots are used for channel estimation and MIMO signal processing, enabling the system to prepare the necessary channel information in advance and efficiently utilize multiple antennas for spatial diversity and multiplexing.
Solution Approach 2:
The patent uses pilot signals as templates or copies of known patterns that are transmitted at specific locations in the time-frequency plane. These pilot copies allow the receiver to estimate channel characteristics and decode MIMO signals by comparing received signals with the expected pilot patterns, enabling efficient frequency resource utilization through multiple antennas.
4Reliability
If HRPD system uses conventional pilot signal placement, then channel estimation is simple, but interference from adjacent cells is not reduced
Solution Approach 1:
The patent places pilot signals at specific predetermined positions in the time-frequency grid with optimized spacing and positioning. By strategically locating pilots at these local positions, the system achieves accurate channel estimation in each cell while minimizing interference from adjacent cells through proper pilot placement and guard period design.
Data Source
AI summary
Methods and apparatus are provided for transmitting data in a communication system with a plurality of antennas. The transmitter generates a first pilot signal and a second pilot signal. Data, the first pilot signal, and the second pilot signal are transmitted over a wireless network. The first pilot signal is transmitted at a first position in a time domain in each transmission time interval of the data over each frequency in a frequency domain used to transmit the data, and the second pilot signal is transmitted at a second position known by the transmitter and a receiver in the time domain and the frequency domain of a transmission time interval.