MIMO Relay Terminal Multiplexing for mmWave Coverage
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Solution Overview
Problem
Millimeter wave (mmWave) wireless communication systems face challenges with poor link budget due to high free space path loss, O2/H2O absorption, and object attenuation, leading to dead spots and throughput penalties in relay communications, especially when MIMO technology is not utilized.
Innovation Solution
Implementing MIMO and multi-user MIMO technology in mmWave communications, with efficient relay selection and link setup methods, allowing for simultaneous data stream multiplexing from Cat B devices to a Cat A relay and then to an access point, reducing air-time and overhead in multi-hopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wireless relaying is used to improve coverage in mmWave systems, then coverage area is improved, but throughput is reduced due to multi-hop transmission and overhead
Solution Approach 1:
The system segments the relay communication into two independent phases: uplink data transmission from STAs to relay, and downlink data transmission from relay to AP. This segmentation allows simultaneous operation of multiple links using different time resources, reducing the total transmission time and overhead while maintaining improved coverage through relay assistance.
Solution Approach 2:
The system implements periodic time-division multiplexing where different links transmit data in alternating time slots. Uplink transmissions from multiple STAs to the relay occur in one phase, followed by downlink transmissions from the relay to AP in another phase. This periodic structure enables efficient resource utilization and reduces overall airtime compared to sequential multi-hop transmission.
2Object-generated harmful factors
If beamforming is used to reduce interference in mmWave systems, then interference between communication links is reduced, but link budget remains poor due to high path loss and absorption
Solution Approach 1:
The system segments the communication path into two separate hops: STA-to-relay and relay-to-AP. Each hop uses beamforming independently to achieve directional gain and reduce interference. This segmentation allows the relay to act as an intermediate beamforming node, multiplying the beamforming benefits across both links while compensating for path loss through the relay's multiple antenna arrays.
Solution Approach 2:
The system merges multiple antenna arrays at the relay node to create a collaborative MIMO system. The relay combines signals from multiple STAs using its multiple receive antennas, processes them through MIMO techniques, and transmits to the AP using multiple transmit antennas. This merging of antenna resources creates spatial diversity and multiplexing gains that improve link budget despite high path loss.
3Productivity
If MIMO technology is implemented in mmWave relay communications, then spectral efficiency is improved, but device complexity increases
Solution Approach 1:
The system segments the MIMO processing complexity across different nodes and time phases. The relay performs MIMO processing for uplink reception from multiple STAs, while the AP performs MIMO processing for downlink transmission. This segmentation distributes the computational burden and allows each node to implement MIMO techniques independently, achieving high spectral efficiency without requiring all devices to have equal complexity.
Solution Approach 2:
The relay acts as an intermediary MIMO node that simplifies the overall system complexity. Instead of requiring direct MIMO communication between all STAs and the AP, the relay mediates the MIMO processing by receiving signals from multiple STAs, performing spatial processing, and transmitting to the AP. This intermediary role enables MIMO benefits while managing device complexity through functional decomposition.
Data Source
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AI summary
A wireless communication system with directional transmission for simultaneously relaying communications between an access point (AP) and multiple radio nodes in the network which are in a first category that supports multiple-input-multiple-output (MIMO) capability, or a second category having different signal processing capabilities. Utilizing a superframe, which is a modification of an existing protocol, a relaying service period (SP) controls multiple simultaneous training and data transmission frames. The AP selects a relay device from the radio nodes based on metrics selected from signal strength, estimation of air time, category of radio node, AoA / AoD, power connectivity. This allows data to be communicated in a MIMO hop from said AP to the selected relay device, with a multi-user (MU) MIMO hop from the selected relay device and a destination radio node (client).