OFDM Preamble Sequence Generation for Multi-Antenna Systems
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Solution Overview
Problem
Current OFDM communication systems using multiple transmission antennas lack a method to generate preamble sequences with a minimum Peak-to-Average Power Ratio (PAPR), which is essential for correct channel estimation and synchronization, leading to interference and reduced performance.
Innovation Solution
The system employs N sequence generators to create preamble sequences of length B/N, mapping these sequences to specific sub-carriers and assigning null data to others, with IFFT processing and guard interval insertion to transmit these sequences over N Tx antennas, enabling channel estimation across all sub-carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transmission antenna is used in OFDM communication systems, then the system complexity is reduced, but the channel estimation accuracy and synchronization performance deteriorate when multiple antennas are deployed
Solution Approach 1:
The patent segments the available sub-carriers into N groups, where each group is assigned to a specific transmission antenna. Each antenna transmits a preamble sequence on its assigned sub-carriers, enabling independent channel estimation for each antenna path while maintaining overall system organization and reducing complexity compared to unsegmented multi-antenna approaches.
Solution Approach 2:
The patent applies local quality by assigning different preamble sequences to different transmission antennas based on their specific channel characteristics. Each antenna's preamble sequence is optimized for its local channel conditions, allowing precise channel estimation tailored to each antenna's propagation environment rather than using a uniform approach for all antennas.
2Use of energy by moving object
If preamble sequences are transmitted without proper PAPR control, then the transmission power efficiency improves, but the signal distortion and receiver performance deteriorate
Solution Approach 1:
The patent changes the PAPR parameter of the preamble sequences by carefully selecting and designing the sequences to have minimum PAPR values. This parameter optimization ensures that the transmitted signals remain within the linear operating range of power amplifiers, preventing signal distortion while maintaining high power efficiency in multi-antenna OFDM systems.
3Productivity
If all sub-carriers are used for data transmission, then the data throughput increases, but the channel estimation capability deteriorates due to lack of reference signals
Solution Approach 1:
The patent performs preliminary action by transmitting channel estimation reference signals (preamble sequences) before actual data transmission on each antenna. These pre-transmitted reference signals enable the receiver to establish accurate channel estimates in advance, which are then used to correctly decode the subsequent data transmission, ensuring both high throughput and accurate channel information.
Data Source
AI summary
A method for generating a preamble sequence in an OFDM (Orthogonal Frequency Division Multiplexing) communication system that uses A sub-carriers in a frequency domain and uses N Tx (Transmission) antennas, includes the steps of: generating N sequences, each having a length of ‘B/N’, by dividing B sub-carriers from among the A sub-carriers by the ‘N’ indicative of the number of the Tx antennas; and mapping, for each of the N sequences, individual components of the sequence to the B/N sub-carriers from among the A sub-carriers on a one by one basis in order to assign the components of the sequence to the B/N sub-carriers, and assigning null data to remaining sub-carriers other than the B/N sub-carriers from among the A-sub-carriers, such that a preamble sequence of a corresponding Tx antenna is generated.