Spatial domain self-decoding of encrypted communication
Various embodiments of the present disclosure provide for a method and apparatuses that perform spatial encoding in a multipath environment such that transmissions on different beams are separately encrypted with complex codes such that when the transmissions on the different beams are received at the receiver, the separate encryptions are cancelled out. The transmissions can also have time delay, gain, and phase modifications made to the transmissions such that the automatic self-decryption is performed within a predefined distance of where the receiver is determined to be. In this way, encryption/decryption keys do not have to be sent to the receiver, and unauthorized devices that intercept the beams at a location other than the receiver location will not be able to decrypt the communication.
1 . A method performed by transmitter node for spatially encrypting a communication in a multipath environment, the method comprising:
determining multipath information for the communication between the transmitter node and a receiver node, wherein the communication comprises a first beam associated with a first set of antenna elements and a second beam associated with a second set of antenna elements;
duplicating a signal associated with the communication into a first signal and a second signal;
applying a first complex code to the first signal that modifies a phase and a gain of the first signal, wherein the first complex code is based on a complex random number generator;
applying a second complex code to the second signal that modifies a phase and a gain of the second signal, wherein the second complex code is based on a function of the first complex code, the first set of antenna elements, the second set of antenna elements, a first power associated with the first set of antenna elements, and a second power associated with the second set of antenna elements; and
transmitting the first signal via the first beam and the second signal via the second beam to a receiver node.
2 . The method of claim 1 , further comprising, prior to the applying the first complex code:
applying a first time delay and a first set of beamforming weights to the first signal based on multipath information associated with the first beam; and
applying a second time delay and a second set of beamforming weights to the second signal based on multipath information associated with the second beam.
3 . The method of claim 2 , wherein prior to determining the multipath information, the method further comprises:
receiving, from the receiver node, a reference signal, wherein the multipath information is based on the reference signal.
4 . The method of claim 3 , further comprising:
receiving from the receiver node, new reference signals at predefined intervals; and
updating the multipath information based on each new reference signal for a respective interval.
5 . The method of claim 1 , wherein the second complex code is determined such that when a first transmission associated with the first signal and a second transmission associated with the second signal are received at the receiver node, a first encryption to the first transmission caused by the first code is canceled out by a second encryption to the second transmission caused by the second code.
6 . The method of claim 1 , further comprising:
updating the first complex code and the second complex code at predefined intervals.
7 . The method of claim 1 , wherein the first beam and the second beam traverse different paths to the receiver node.
8 . The method of claim 1 , wherein the first signal and the second signal are identical prior to the first set of beamforming weights and the second set of beamforming weights being applied.
9 . The method of claim 1 , wherein the first beam and the second beam are associated with spatial multiplexing channels with highest signal strengths.
10 . The method of claim 1 , wherein the first power associated with the first set of antenna elements is based at least in part on the gain of the first signal and a number of antenna elements of the first set of antenna elements.
11 . The method of claim 1 , wherein the second power associated with the second set of antenna elements is based at least in part on the gain of the second signal and a number of antenna elements of the second set of antenna elements.
12 . A transmitter node configured to spatially encrypt a communication in a multipath environment comprising a radio interface and processing circuitry configured to:
determine multipath information for the communication between the transmitter node and a receiver node, wherein the communication comprises a first beam associated with a first set of antenna elements and a second beam associated with a second set of antenna elements;
duplicate a signal associated with the communication into a first signal and a second signal;
apply the first signal with a first complex code that modifies a phase and a gain of the first signal, wherein the first complex code is based on a complex random number generator;
apply the second signal with a second complex code that modifies a phase and a gain of the second signal, wherein the second complex code is based on a function of the first complex code, the first set of antenna elements, the second set of antenna elements, a first power associated with the first set of antenna elements, and a second power associated with the second set of antenna elements; and
transmit, to the receiver node, the first signal via the first beam and the second signal via the second beam.
13 . The transmitter node of claim 11 , wherein the processing circuitry is further configured to, prior to the applying the first complex code:
apply a first time delay and a first set of beamforming weights to the first signal based on multipath information associated with the first beam; and
apply a second time delay and a second set of beamforming weights to the second signal based on multipath information associated with the second beam.
14 . The transmitter node of claim 13 , wherein prior to determining the multipath information, the processing circuitry is further configured to:
receive, from the receiver node, a reference signal, wherein the multipath information is based on the reference signal.
15 . The transmitter node of claim 14 , wherein the processing circuitry is further configured to:
receive from the receiver node, new reference signals at predefined intervals; and
update the multipath information based on each new reference signal for a respective interval.
16 . The transmitter node of claim 12 , wherein the second complex code is determined such that when a first transmission associated with the first signal and a second transmission associated with the second signal are received at the receiver node, a first encryption to the first transmission caused by the first code is canceled out by a second encryption to the second transmission caused by the second code.
17 . The transmitter node of claim 12 , wherein the processing circuitry is further configured to:
update the first complex code and the second complex code at predefined intervals.
18 . The transmitter node of claim 12 , wherein the first beam and the second beam traverse different paths to the receiver node.
19 . The transmitter node of claim 12 , wherein the first signal and the second signal are identical prior to the first set of beamforming weights and the second set of beamforming weights being applied.
20 . The transmitter node of claim 12 , wherein the first beam and the second beam are associated with spatial multiplexing channels with highest signal strengths.