GSM Beamforming Using Common and Antenna-Specific Training Sequences
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Solution Overview
Problem
Current GSM systems lack efficient beamforming techniques due to the absence of fast feedback channels and cell-specific reference signals, limiting the implementation of closed-loop beamforming for enhanced spectrum efficiency and link performance.
Innovation Solution
The implementation of a method that allows for beamforming transmission and reception using multiple antennas in GSM/EGPRS systems, employing a common training sequence for beamformed data bursts and antenna-specific sequences for non-beamformed bursts, without requiring new fast feedback channels or cell-specific reference signals, and utilizing codebook-based beamforming to adapt signal phases and amplitudes over longer time periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If closed-loop beamforming is implemented to improve spectrum efficiency and link performance, then spectrum efficiency and link performance are improved, but the system requires fast feedback channels and cell-specific reference signals which increase device complexity and system overhead
Solution Approach 1:
The system uses existing uplink data bursts and training sequences to provide the feedback information needed for beamforming, eliminating the need for separate fast feedback channels. The training sequences already present in the data bursts serve dual purposes: data transmission and channel feedback.
Solution Approach 2:
The training sequences in the data bursts serve multiple functions: they enable data transmission, provide channel estimation, and simultaneously act as feedback signals for beamforming adjustments. This multi-functionality eliminates the need for dedicated feedback channels and reference signals.
2Reliability
If beamforming techniques are introduced to enhance link performance, then link performance is improved, but backward compatibility with existing GSM air interface is compromised
Solution Approach 1:
The patent implements feedback mechanisms using existing uplink training sequences, allowing the base station to adjust beamforming weights based on received signal quality without requiring new air interface protocols. The feedback is embedded in the existing data burst structure.
Solution Approach 2:
The system adjusts beamforming parameters (weights, phases, amplitudes) dynamically based on channel conditions while maintaining the same underlying GSM air interface structure. Existing training sequences are reinterpreted and reused for beamforming control purposes.
3Productivity
If multiple antennas are used for beamforming transmission, then spectrum efficiency is improved, but energy consumption increases
Solution Approach 1:
The system performs beamforming adjustments periodically based on changes in channel conditions rather than continuously, reducing the energy consumption of multiple transmit antennas while maintaining spectrum efficiency benefits during active beamforming periods.
Data Source
AI summary
The embodiments herein relate to a method in a transmitter for transmitting a data burst to a receiver in a system supporting GSM and/or EGPRS. The transmitter is arranged to make its transmissions with or without beamforming. The transmitter comprises at least two Tx antennas. When the data burst is beamformed, the transmitter transmits the data burst to the receiver through at least one of the at least two Tx antennas. The data burst comprises a common training sequence. When the data burst is non-beamformed, the transmitter transmits the data burst to the receiver through each of the at least two Tx antennas. The data burst comprises a respective antenna specific training sequence.