A method for channel estimation, the method comprising: determining, by a communications device, position information of a main sink having a primary transmission path to the communications device and of at least one mirror sink associated with the main sink by at least one secondary transmission path between the main sink and the communications device, wherein the mirror sink is imaginary sink that corresponds to the main sink, relative to a reflective surface; estimating, by the communications device, primary channels between the communications device and antennas of an antenna array of the main sink and secondary channels between the communications device and antennas of an antenna array of the at least one mirror sink, the estimating is at least partially based on the position information of the main sink and the at least one mirror sink and position information of the antennas in the antenna arrays; and instructing, by the communications device, use of the estimated primary channels and the estimated secondary channels; wherein instructing the use of the estimated primary channels and the estimated secondary channels comprises saving information regarding the estimated primary channels and the estimated secondary channels in a database, and signalling indications of the estimated primary channels and the estimated secondary channels; wherein determining the position information of the at least one mirror sink comprises deriving the position information of the at least one mirror sink in accordance with the position information of the main sink and physical environmental deployment, PED, information regarding a physical layout of a communications system including the communications device and the main sink, the PED information comprises information about at least one of a number, a location, a type, a shape, a penetration property, and an orientation of surfaces that reflect transmissions, and a number, a location, a type, a shape, an absorption property, a penetration property, and an orientation of surfaces that absorb transmissions. determining, by a communications device, position information of a main sink having a primary transmission path to the communications device and of at least one mirror sink associated with the main sink by at least one secondary transmission path between the main sink and the communications device, wherein the mirror sink is imaginary sink that corresponds to the main sink, relative to a reflective surface; estimating, by the communications device, primary channels between the communications device and antennas of an antenna array of the main sink and secondary channels between the communications device and antennas of an antenna array of the at least one mirror sink, the estimating is at least partially based on the position information of the main sink and the at least one mirror sink and position information of the antennas in the antenna arrays; and instructing, by the communications device, use of the estimated primary channels and the estimated secondary channels; wherein instructing the use of the estimated primary channels and the estimated secondary channels comprises saving information regarding the estimated primary channels and the estimated secondary channels in a database, and signalling indications of the estimated primary channels and the estimated secondary channels; wherein determining the position information of the at least one mirror sink comprises deriving the position information of the at least one mirror sink in accordance with the position information of the main sink and physical environmental deployment, PED, information regarding a physical layout of a communications system including the communications device and the main sink, the PED information comprises information about at least one of a number, a location, a type, a shape, a penetration property, and an orientation of surfaces that reflect transmissions, and a number, a location, a type, a shape, an absorption property, a penetration property, and an orientation of surfaces that absorb transmissions.