Today I attended a South Seattle meetup on WiFi and its vulnerabilities. As someone with next to no knowledge of radio, it was a revelation for me to realize the following over these last months:
- Everything is a radio, including WiFi and Bluetooth.
- Radio is a software application called software-defined radio (SDR), something that hackers are apparently quite interested in.
- Radio is directional; this is probably based on the directionality of an antenna, that is, the capacity of the antenna to control the trajectory of the signal.
In the same vein, any waveform can probably be transmitted with directionality.
Hence, what I learned about today, “directional” WiFi, a protocol that attempts to shape the modulated waveforms of wireless from omni-directional antenna—probably those on a router, I would imagine—into “beams.” It might be IEEE 802.11ad, as described by Thomas Nitsche et al in IEEE 802.11ad: Directional 60 GHz Communication for Multi-Gbps Wi-Fi at http://networks.rice.edu/files/2014/10/11adPaper.pdf.
Chuck Fung’s 2011 thesis on Basic Antenna Theory and Application focuses on directional antennas, including dipole antennas. I had considered that dipole antennas might be a possibility for line-of-sight (LOS) transmission of waveforms between two mobbing houses located on either side of the house to be acquired; at least, it appeared that might be possible, for example, if the dipoles were sunk into the ground and the ultra-low frequency (ULF) band of 300-3000 Hz was used. This band is used for below ground communication within mines and, one might think, could be suitable to send vibrations through a common slab or through the earth under the house sought for acquisition after the residents are expelled by the harassment. Geophysics uses the very low frequency (VLF) band of 3-30 kHz. I don’t know about seismographic technologies but these are certainly of interest to building engineers, especially in fragile environments like my own slide-prone neighborhood over Lake Washington.
Cisco’s 2007 document Omni Antenna vs. Directional Antenna compares the use of both types of antennas with wireless systems at http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/82068-omni-vs-direct.html#intro.
I haven’t looked at this yet and this is all I know about it but it sounds like it could be analogous to the directionality of a parametric speaker and perhaps even paired with the technology. I’m just guessing though. If the directionality was precise enough, I wonder if the broadcast of packets could be focused in a manner that would limit a transmission to a single device, for example.
I’m sure there are a lot of network technologists and hackers out there who’d probably be quick to grasp the capabilities of directional WiFi to “mob” or harass neighbors, if such capabilities do exist.
Feel free to comment.