Hybrid Time-Spatial Multiplexing for Wireless Broadcast
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Solution Overview
Problem
Conventional beamforming techniques are ineffective for transmitting broadcast messages to multiple mobile stations within a coverage region, resulting in lower signal levels and limited coverage, as they cannot utilize beamforming weights for each individual station, leading to impractical and unreliable signal reception.
Innovation Solution
A hybrid time-spatial multiplexing technique divides the coverage region into segments, assigns mobile stations to these segments based on their location, and computes beamforming weights to produce focused radiation beam patterns for each segment, allowing for time-division multiplexed transmission of broadcast messages to achieve beamforming gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a base station uses a radiation beam pattern that covers the entire cell to transmit a broadcast message, then the broadcast message can reach multiple mobile stations, but the signal level becomes lower and coverage is limited
Solution Approach 1:
The coverage region is divided into multiple segments, and beamformed broadcast messages are transmitted to each segment separately using dedicated beamforming weights. This segmentation allows the system to achieve both wide coverage (by covering multiple segments) and high signal levels (by focusing energy in each segment), resolving the contradiction between coverage area and signal reliability.
2Adaptability or versatility
If conventional beamforming weights are used for broadcast messages, then transmission to multiple mobile stations is possible, but beamforming gain cannot be achieved
Solution Approach 1:
By segmenting the coverage region and computing separate beamforming weights for each segment, the system maintains the ability to transmit to multiple mobile stations (adaptability) while achieving beamforming gain in each segment (power efficiency). The segmentation enables the system to apply directional beamforming locally while still providing broadcast service to multiple stations across different segments.
3Reliability
If beamforming is applied to broadcast messages intended for multiple mobile stations, then signal focus is improved, but the technique is not applicable when locations are unknown
Solution Approach 1:
The system performs preliminary actions by dividing the coverage region into segments and pre-computing beamforming weights for each segment before actual broadcast transmission. When a mobile station's location is unknown, the system can still transmit beamformed messages to all segments, ensuring the message reaches the station wherever it is located. This preliminary segmentation and weight computation enables beamforming to work effectively even when receiver locations are not known in advance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the coverage and reliability of broadcast messages by focusing the signal on specific segments, achieving beamforming gain and improving signal strength and range compared to conventional methods.
Implementation Method 1
The base station computes beamforming antenna weights which are configured to produce a synthesized radiation beam pattern from a plurality of antennas of the base station to a particular segment in the region
Implementation Method 2
the signals received by a communication device on its multiple antennas from another device are coherently combined, and the signals transmitted from multiple antennas of a communication device are weighted in both phase and magnitude so that they will be coherently combined at the intended destination communication device
Data Source
AI summary
A hybrid time-spatial multiplexing technique is provided for beamforming broadcast messages to mobile stations that may be within a coverage region or cell of a base station. The coverage region is divided into a plurality of segments. The mobile stations are assigned to at least one of the segments based on their locations within the coverage region or other criteria. The base station computes beamforming antenna weights which are configured to produce a radiation beam pattern from a plurality of antennas of the base station to respective ones of each of the plurality of segments in the region. A broadcast message is transmitted to each segment of the region in a time-division multiplexed manner using the beamforming antenna weights associated with the radiation beam pattern for the corresponding segment.