A method, comprising: receiving, at an apparatus, from a first location, at least: a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element, and a third radio signal transmitted by a third antenna element; the apparatus discriminating between the received at least first, second and third radio signals (50A, 50B, 50C); the apparatus receiving location information related to the first location; the apparatus obtaining, from the received at least first, second and third radio signals (50A, 50B, 50C), displacement information that is dependent upon the relative displacements of the at least first, second and third antenna elements (32A, 32B, 32C); the apparatus estimating a bearing of the apparatus from the first location using: the received at least first, second and third radio signals (50A, 50B, 50C), and the displacement information; and the apparatus estimating a position of the apparatus using: the estimated bearing, the location information related to the first location, and constraint information for enabling a determination of the location of the apparatus along the estimated bearing, wherein the constraint information is different from the location information related to the first location and is determined independently of the received first, second and third radio signals. receiving, at an apparatus, from a first location, at least: a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element, and a third radio signal transmitted by a third antenna element; a first radio signal transmitted by a first antenna element, a second radio signal transmitted by a second antenna element, and a third radio signal transmitted by a third antenna element; the apparatus discriminating between the received at least first, second and third radio signals (50A, 50B, 50C); the apparatus receiving location information related to the first location; the apparatus obtaining, from the received at least first, second and third radio signals (50A, 50B, 50C), displacement information that is dependent upon the relative displacements of the at least first, second and third antenna elements (32A, 32B, 32C); the apparatus estimating a bearing of the apparatus from the first location using: the received at least first, second and third radio signals (50A, 50B, 50C), and the displacement information; and the received at least first, second and third radio signals (50A, 50B, 50C), and the displacement information; and the apparatus estimating a position of the apparatus using: the estimated bearing, the location information related to the first location, and constraint information for enabling a determination of the location of the apparatus along the estimated bearing, wherein the constraint information is different from the location information related to the first location and is determined independently of the received first, second and third radio signals. the estimated bearing, the location information related to the first location, and constraint information for enabling a determination of the location of the apparatus along the estimated bearing, wherein the constraint information is different from the location information related to the first location and is determined independently of the received first, second and third radio signals.