Multi-band Directional Scanning for mmWave Link Establishment
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Solution Overview
Problem
Millimeter-wave (mmWave) network devices experience increased propagation loss due to line-of-sight obstructions and atmospheric conditions, leading to longer scan times during passive directional scanning for establishing wireless communication links.
Innovation Solution
Implementing multi-band directional scanning by using a first radio operating below the mmWave band to receive a probe request from a second network device, allowing the second radio operating within the mmWave band to transmit probe responses in specific sector directions, thereby reducing the need for beacon frames and minimizing scan times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive directional scanning is used at mmWave band, then directional communication link can be established, but scan time becomes excessively long (102.4 seconds)
Solution Approach 1:
The patent introduces a sub-6 GHz frequency band as an intermediary communication channel between the two mmWave devices. This intermediary band carries probe requests and responses that enable devices to discover each other's sector directions without requiring exhaustive mmWave beam scanning, thereby dramatically reducing scan time while still establishing reliable directional mmWave communication links.
Solution Approach 2:
The patent segments the communication process into two distinct phases: (1) initial discovery and coordination using sub-6 GHz omnidirectional communication, and (2) directional data transmission using mmWave beams. This segmentation allows the time-consuming directional scanning to be replaced by faster omnidirectional signaling for the critical path of link establishment.
2Productivity
If mmWave band is used for communication, then wider channel bandwidth and higher throughput are achieved, but propagation loss increases due to line-of-sight obstructions and atmospheric conditions
Solution Approach 1:
The sub-6 GHz band serves as an intermediary that is less susceptible to propagation losses. It carries control signaling (probe requests/responses) that coordinate the directional beams, allowing the mmWave band to focus on high-throughput data transmission while the intermediary handles the robust signaling needed to overcome propagation challenges.
Solution Approach 2:
The patent adds a frequency dimension to the communication system by utilizing two distinct frequency bands (sub-6 GHz and mmWave) simultaneously. Each band serves a different functional dimension: sub-6 GHz for robust control signaling and mmWave for high-capacity data transmission, thereby overcoming the limitations of using a single band.
Data Source
AI summary
Examples described herein provide multi-band directional scanning. Examples may include receiving, by a first radio of a first network device operating at a first frequency band below the millimeter-wave (mmWave), a probe request from a second network device indicating a protocol and a particular sector receiving direction of the second network device, and in response to the protocol indicated by the probe request, transmitting, by a second radio of the first network device operating at a second frequency band within the mmWave, a probe response in each of one or more sector transmitting directions, wherein the second network device receives one or more probe responses in the particular sector receiving direction.