METHOD AND APPARATUS FOR FACILITATING DIRECTION FINDING

1 - 52 . (canceled)

53 . A method, comprising:

detecting, by an apparatus, at least one indication frame from another apparatus,

determining properties associated with transmission of at least one subsequent frame from the another apparatus on the basis of the at least one indication frame, and

gathering measurement information for direction calculation on the basis of the determined properties and the at least one subsequent frame from the another apparatus.

54 . The method of claim 53 , further comprising: calculating at least relative direction of the another apparatus on the basis of the measurement information and the determined properties, or

sending a report comprising the measurement information to an apparatus for direction calculation.

55 . The method of claim 53 , wherein the at least one subsequent frame is at least one of a sounding frame and an acknowledgement to a quality of service frame of sub-type ‘no data’.

56 . The method of claim 53 , wherein the indication frame comprises at least one of:

properties of transmit antenna elements and the amount of subsequent frames usable for calculating the at least relative direction of the another apparatus.

57 . The method of claim 53 , wherein the at least one subsequent frame comprises at least two frames transmitted or received by different antenna elements.

58 . The method of claim 57 , wherein the indication frame indicates that subsequent frames are transmitted from a plurality of antenna elements.

59 . The method of claim 53 , wherein the method is for a wireless local area network.

60 . A method, comprising: generating at least one indication frame indicating properties associated with transmission of at least one subsequent frame usable for direction calculation,

transmitting the at least one indication frame for at least one other apparatus, and

transmitting at least one subsequent frame usable for direction calculation in the at least one other apparatus in accordance with the properties indicated in the indication frame.

61 . The method of claim 60 , further comprising:

receiving, after the at least one subsequent frame, a report comprising measurement information generated on the basis of the indication frame and the at least one subsequent frame from the another apparatus, and

performing direction calculation on the basis of the measurement information.

62 . The method of claim 60 , wherein the at least one subsequent frame is at least one of a sounding frame and an acknowledgement to a quality of service frame of sub-type ‘no data’.

63 . The method of claim 60 , wherein the at least one subsequent frame comprises at least two subsequent frames and the indication frame indicates that the at least two subsequent frames are transmitted from a plurality of antenna elements.

64 . An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

detect at least one indication frame from another apparatus,

determine properties associated with transmission of at least one subsequent frame from the another apparatus on the basis of the at least one indication frame, and

gather measurement information for direction calculation on the basis of the determined properties and the at least one subsequent frame from the another apparatus.

65 . The apparatus of claim 64 , wherein the apparatus is further configured to:

calculate at least relative direction of the another apparatus on the basis of the measurement information and the determined properties, or

send a report comprising the measurement information to an apparatus for direction calculation.

66 . The apparatus of claim 64 , wherein at least one subsequent frame is at least one of a sounding frame and an acknowledgement to a quality of service frame of sub-type ‘no data’.

67 . The apparatus of claim 64 , wherein the indication frame comprises at least one of:

properties of transmit antenna elements and the amount of subsequent frames usable for calculating the at least relative direction of the another apparatus.

68 . The apparatus of claim 64 , wherein the at least one subsequent frame comprises at least two frames transmitted or received by different antenna elements.

69 . The apparatus of claim 68 , wherein the indication frame indicates that subsequent frames are transmitted from a plurality of antenna elements.

70 . An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:

generate at least one indication frame indicating properties associated with transmission of at least one subsequent frame usable for direction calculation,

transmit the at least one indication frame for at least one other apparatus, and

transmit at least one subsequent frame usable for direction calculation in the at least one other apparatus in accordance with the properties indicated in the indication frame.

71 . The apparatus of claim 70 , wherein the apparatus is further configured to:

receive, after the at least one subsequent frame, a report comprising measurement information generated on the basis of the indication frame and the at least one subsequent frame from the another apparatus, and

perform direction calculation on the basis of the measurement information.

72 . The apparatus of claim 70 , wherein the at least one subsequent frame is at least one of a sounding frame and an acknowledgement to a quality of service frame of sub-type ‘no data’.

73 . The apparatus of claim 72 , wherein the at least one subsequent frame comprises at least two subsequent frames and the indication frame indicates that the at least two subsequent frames are transmitted from a plurality of antenna elements.