Method for alignment of multi-beam antennas in a non line-of-sight scenario

1. A method for alignment of a first node with at least one secondary node in a wireless communication network, the first node being adapted to direct a plurality of first node antenna beams at corresponding designated first node antenna beam pointing direction angles, wherein for each desired first node antenna beam, the method comprises, for each secondary node:

directing a first node antenna beam in its designated pointing direction;

using a secondary node antenna beam generated by the secondary node for scanning a volume of signal reflections and/or signal diffractions generated due to reflection and/or diffraction of the first node antenna beam with at least one object between the first node and the secondary node, wherein the scanning includes

detecting at least one signal property of the reflected signals and/or diffracted signals, and storing secondary node antenna beam pointing direction angles that result in the at least one signal property of the reflected signals and/or diffracted signals exceeding a corresponding threshold level;

wherein the method further comprises:

exchanging information between the nodes, said information comprising first node antenna beam pointing direction angles and the secondary node antenna beam pointing direction angles resulting in said signal property exceeding the corresponding threshold level; and

selecting a first node antenna beam pointing direction angle and selecting a secondary node antenna beam pointing direction angle from the antenna beam pointing direction angles comprised in said exchanged information for communication between the first node and each secondary node.

2. The method according to claim 1 , further comprising the steps of:

each secondary node, sequentially using its secondary node antenna beam for scanning said volume for a certain first node antenna beam; and

the first node switching to another first node antenna beam, until the desired first node antenna beams have been used.

3. The method according to claim 1 , further comprising the steps of:

all secondary nodes using their corresponding secondary node antenna beams for scanning said volume for a certain first node antenna beam at the same time; and

the first node switching to another first node antenna beam, until the desired first node antenna beams have been used.

4. The method according to claim 1 , wherein all secondary nodes are in receive mode and each secondary node detects signals transmitted by the first node.

5. The method according to claim 1 , wherein all secondary nodes are in transmit mode and the transmitted signals are differentiated such that the first node can identify each secondary node individually.

6. The method according to claim 1 , wherein the first node comprises an antenna arrangement that in turn comprises a beam-forming network in the form of a Butler matrix, a Rothman lens, a Blass matrix or a phased array.

7. The method according to claim 1 , wherein the first node comprises an antenna arrangement that is adapted for digital beamforming.

8. The method according to claim 1 , wherein said information comprises measures of said signal property.

9. The method according to claim 1 , wherein said signal property includes at least one of relative signal strength, Signal to interference ratio, SIR, Signal to noise and interference ratio, SNIR, Signal to noise ratio, SNR, Bit Error Rate, BER, Block Error Rate, BLER, Channel Quality Indicator, CQI, Received Signal Strength Indication, RSSI, and re-transmission frequency.

10. The method according to claim 1 , wherein the method comprises the step of saving the exchanged information, at least at the first node.

11. The method according to claim 1 , wherein each antenna beam pointing direction angle comprised in said exchanged information is identified either by a specific angular measure or by an identification reference.