Automatic Service Activation

• US 20060045058A1
• Filed: 08/31/2005
• Published: 03/02/2006
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Jonsson, Daniel, Ljungberg, Richard, Lundgren, Jonas
• Granted Patent: US 7,697,493 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems

Abstract

The invention relates to wireless communication systems wherein services involving two or more stations in the system may be activated automatically. Data is communicated between airborne stations (A, B) according to a TDMA protocol, where the data is transmitted in time slots organized in frames of a repeating frame structure. A link address is associated with at least one time slot, and the stations select link addresses for transmission of data according to a self-organizing transmission algorithm. Each station (A, B) broadcasts data messages of a first type (D₁) at a first repetition rate and receives such corresponding messages from the other stations (A, B). At least based on the received data messages of the first type (D₁), each station determines whether a service activation criterion is fulfilled with respect to at least one other station (A, B), for example by the other station being located within a limit distance (r_A). If the service activation criterion is fulfilled, the station (A, B) starts to transmit data messages of a second type (D₂), which pertain to a service that involves the station itself and the at least one other station (A, B).

Claims

1. A method of communicating data between airborne stations (A, B) in a time division multiple access system, where the data is transmitted in time slots (s(1), . . . , s(n)) which are organized in frames (F(i)) of a repeating frame structure (110), a link address (A1, . . . , Ak) for transmission of data is associated with at least one time slot (s(1), . . . , s(m)) in each frame (F(i)), the stations (A, B) selecting link addresses (A1, . . . , Ak) for transmission of data according to a self-organizing transmission algorithm, the method comprising:

broadcasting from each station (A, B) a data message of a first type (D₁) at a first repetition rate, and

receiving in each station (A, B) data messages of the first type from other stations (A, B), wherein a service involving at least two stations (A, B) being accomplished via an exchange of data messages of a second type (D₂) that are transmitted at a second repetition rate which is different from the first repetition rate, the method comprising;

determining in each station (A, B), based on any received data messages of the first type (D₁) or the second type (D₂), whether a service activation criterion is fulfilled with respect to at least one other station (A, B), and if so

transmitting, from each station (A, B) having found said criterion to be fulfilled, data messages of the second type (D₂) at the second repetition rate to accomplish said service with respect to all stations (A, B) which have found said criterion to be fulfilled.

2. A method according to claim 1, wherein the method, in each station (A, B) having found the service activation criterion to be fulfilled, comprising:

determining whether a free link address exists (A1, A2) for transmission of data messages of the second type (D₂), and if so

transmitting the data messages of the second type (D₂) in time slots associated with one of said free link addresses (A1).

3. A method according to claim 2, wherein the second repetition rate being substantially higher than the first repetition rate.

4. A method according to claim 3, wherein the data message of the second type (D₂) comprising a current link address field (LAC) and a previous link address field (LAP) of the transmitting station, and provided that a station (A) transmits data messages of the second type (D₂) at a current link address (A1) the method for this station (A) comprising:

listening for data messages of the second type (D₂) at all link addresses (A2, . . . , Ak) allocated for transmission of data messages of the second type different from the current link address (A1), and provided that the station (A) has transmitted the data messages of the second type (D₂) at the current link address (A1) during at least a minimum time period,

interrupting the transmission of data messages of the second type (D₂) at randomly selected time slots, and during each such time slot

listening for any data messages of the second type (D₂) transmitted from other stations (B, C, D) at the current link address (A1), and if such a transmission is found,

releasing the current link address (A1), otherwise

continuing to transmit data messages of the second type (D₂) at the current link address (A1) until a service deactivation criterion is found be fulfilled.

5. A method according to claim 4, wherein in case the station (A) finds a data message of the second type (D₂) transmitted from another station (B) at the particular link address (A1), the method for the station (A) comprising:

determining whether a free link address (A3, Ak) exists for transmission of data messages of the second type (D₂), and if so

selecting one of said free link addresses (A3),

transmitting data messages of the second type (D₂) in the time slots associated with the selected link address (A3), and

updating the current and previous link address fields (LAC;

LAP) such that the current link address field (LAC) specifies the selected link address (A3) and the previous link address field (LAP) specifies the released link address (A1), otherwise

listening for data messages of the second type (D₂) at all link addresses (A1, . . . , Ak) allocated for transmission of data messages of the second type (D₂).

6. A method according to claim 5, wherein if in said listening step at least one free link address is detected, the method comprises:

selecting one of the at least one free link addresses (A3),

transmitting data messages of the second type (D₂) in the time slots associated with the selected link address (A3), and

updating the current and previous link address fields (LAC;

LAP) such that the current link address field (LAC) specifies the selected link address (A3) and the previous link address field (LAP) specifies an initial default address.

7. A method according to claim 4, wherein in each station (A, B, C, D) whether the service deactivation criterion is fulfilled based on received data messages of at least one of the first and second types (D₁, D₂).

8. A method according to claim 2, wherein said service being an automatic collision avoidance service, the data message of the first type (D₁) comprising information about the transmitting station'"'"'s position and velocity, and the service activation criterion relating to an estimated risk for a collision between two or more station carrying vehicles (V_A, V_B), the method comprising:

determining, in each station a distance between the station and the other stations based on received data messages of the first type (D₁) or the second type (D₂), and

regarding the service activation criterion for a particular station (A) as fulfilled if the distance between the particular station (A) and at least one other station (B) is less than a first limit distance (r_A).

9. A method according to claim 8, wherein the first limit distance (r_A) depending on a relationship between a velocity vector of the particular station (A) and a respective velocity vector of the at least one other station (B).

10. A method according to claim 8, wherein regarding the service deactivation criterion for the particular station (A) as fulfilled with respect to another station (D) if the distance between the particular station (A) and the other station (D) exceeds a second limit distance (r_D).

11. A method according to claim 8, wherein maintaining in each station a listing (550) of any current users of the automatic collision avoidance service, the listing (550) for each user comprising information about a respective position (LAT, LONG, ALT), velocity (VEX, VELY, VELZ), current link address (LAC), time stamp indicating a point in time when a latest message of the second type (D₂) was received at the current link address (LAC), and previous link address (LAP), and

repeatedly updating the listing (550) based on data messages of the second type (D₂) received from at least one other station.

12. A method according to claim 2, wherein said service being an automatic resource coordination service, the data message of the first type (D₁) comprising information about at least one resource parameter of a vehicle (V_A, V_B) carrying the respective station (A, B) and at least one local environment parameter registered by the vehicle (V_A, V_B), the method comprising:

allocating at least one mission value (MISN) to each of at least two vehicles (V_A, VB) based on received data messages of the second type (D₂), and

determining whether the service activation criterion is fulfilled based on a situation analysis performed with respect to any received data messages of the first type (D₁) or the second type (D₂).

13. A computer program directly loadable into the internal memory of a digital computer, comprising program code for communicating data between airborne stations (A, B) in a time division multiple access system, wherein the program code comprises sets of instructions for:

broadcasting from each station (A, B) a data message of a first type (D1) at a first repetition rate, and

receiving in each station (A, B) data messages of the first type from other stations (A, B), wherein a service involving at least two stations (A, B) being accomplished via an exchange of data messages of a second type (D₂) that are transmitted at a second repetition rate which is different from the first repetition rate, the method comprising;

determining in each station (A, B), based on any received data messages of the first type (D₁) or the second type (D₂), whether a service activation criterion is fulfilled with respect to at least one other station (A, B), and if so

transmitting, from each station (A, B) having found said criterion to be fulfilled, data messages of the second type (D₂) at the second repetition rate to accomplish said service with respect to all stations (A, B) which have found said criterion to be fulfilled.

14. A computer program product in a computer readable medium having computer program code recorded thereon, wherein the program code includes sets of instructions comprising:

first computer instructions for broadcasting from each station (A, B) a data message of a first type (D₁) at a first repetition rate, and

second computer instructions for receiving in each station (A, B) data messages of the first type from other stations (A, B), wherein a service involving at least two stations (A, B) being accomplished via an exchange of data messages of a second type (D₂) that are transmitted at a second repetition rate which is different from the first repetition rate, the method comprising;

third computer instructions for determining in each station (A, B), based on any received data messages of the first type (D₁) or the second type (D₂), whether a service activation criterion is fulfilled with respect to at least one other station (A, B), and if so

fourth computer instructions for transmitting, from each station (A, B) having found said criterion to be fulfilled, data messages of the second type (D₂) at the second repetition rate to accomplish said service with respect to all stations (A, B) which have found said criterion to be fulfilled.

15. A station for wirelessly communicating data with airborne stations in a time division multiple access system, where the data is transmitted in time slots (s(1), . . . , s(n)) which are organized in frames (F(i)) of a repeating frame structure (110), a link address (A1, . . . , Ak) for transmission of data is associated with at least one time slot (s(1), . . . , s(m)) in each frame (F(i)), the stations selecting link addresses (A1, . . . , Ak) for transmission of data according to a self-organizing transmission algorithm, the station comprising:

a transmitter (510) adapted to broadcast data messages of a first type (D₁) at a first repetition rate, and

a receiver (520) adapted to receive data messages of the first type (D₁) from other stations (A, B), wherein

a service involving at least two stations (A, B) in the system is accomplishable via an exchange of data messages of a second type (D₂) that are transmitted at a second repetition rate which is different from the first repetition rate, the station comprises a processing means (540) adapted to

determine, based on any received data messages of the first type (D₁) or the second type (D₂), whether a service activation criterion is fulfilled with respect to at least one other station (A, B), and if so control the transmitter (510) to

transmit data messages of the second type (D₂) at the second repetition rate to accomplish said service with respect to the station itself and the at least one other station (A, B).

16. A station according to claim 15, wherein the second repetition rate is substantially higher than the first repetition rate.

17. A station according to claim 15, wherein the data message of the second type (D₂) comprises a current link address field (LAC) and a previous link address field (LAP) of the station, and when station transmits data messages of the second type (D₂) at a current link address (A1), the processing means (540) is adapted to

control the receiver (520) to listen for data messages of the second type at all link addresses (A2, . . . , Ak) allocated for transmission of data messages of the second type different from the current link address (A1), and provided that the station (A) has transmitted the data messages of the second type (D₂) at the current link address (A1) during at least a minimum time period,

control the transmitter (510) to interrupt the transmission of data messages of the second type (D₂) at randomly selected time slots, and during each such time slot

control the receiver (520) to listen for any data messages of the second type (D₂) transmitted from other stations at the current link address (A1), and if such a transmission is found,

release the current link address (A1), otherwise

control the transmitter (510) to continue to transmit data messages of the second type (D₂) at the current link address (A1) until a service deactivation criterion is found be fulfilled.

18. A station according to claim 17, wherein in case a transmission of data messages of the second type (D₂) from another station is found at the current link address (A1), the processing means (540) is adapted to

determine whether a free link address exists (A3, Ak) for transmission of data messages of the second type (D₂) and if so

select one of said free link addresses (A3),

control the transmitter (510) to transmit data messages of the second type (D₂) in the time slots associated with the selected link addresses (A3), and

update the current and previous link address fields (LAC;

LAP) such that the current link address field (LAC) specifies the selected link address (A3) and the previous link address field (LAP) specifies the released link address (A1), otherwise

control the receiver (520) to listen for data messages of the second type (D₂) at all link addresses (A1, . . . , Ak) allocated for transmission of data messages of the second type (D₂).

19. A station according to claim 17, wherein the processing means (540) is adapted to determine whether the service deactivation criterion is fulfilled based on received data messages of at least one of the first and second types (D₁, D₂).

20. A station according to claim 15, wherein said service is an automatic collision avoidance service, the data message of the first type (D₂) comprises information about the transmitting station'"'"'s position and velocity, the service activation criterion relating to an estimated risk for a collision between two or more station carrying vehicles (V_A, V_B), and the processing means (540) is adapted to

determine a distance between the station and other stations based on any received data messages of the first type (D₁) or the second type (D₂), and

regard the service activation criterion as fulfilled if the distance between the station (A) and at least one other station (B, C) is less than a first limit distance (r_A).

21. A station according to claim 20, wherein the first limit distance (r_A) depends on a relationship between a velocity vector of the particular station (A) and a respective velocity vector of the at least one other station (B).

22. A station according to claim 19, wherein the processing means (540) is adapted to regard the service deactivation criterion for the station (A) as fulfilled with respect to another station (D) if the distance between the station (A) and the other station (D) exceeds a second limit distance (r_D).

23. A station according to claim 20, wherein it comprises a listing (550) of any current users of the automatic collision avoidance service, the listing (550) for each user comprising information about a respective position (LAT, LONG), velocity (VELX, VELY, VELZ), current link address (LAC), time stamp indicating a point in time when a latest message of the second type (D₂) was received at the current link address (LAC), and previous link address (LAP), and the processing means (540) is adapted to repeatedly update the listing (550) based on data messages of the second type (D₂) received from at least one other station.

24. A station according to claim 15, wherein said service is an automatic resource coordination service, the data message of the first type (D₁) comprises information about at least one resource parameter of a vehicle (V_A, V_B) carrying the respective station (A, B) and at least one local environment parameter registered by the vehicle (V_A, V_B), and the processing means (540) is adapted to

allocate at least one mission value (MISN) to each of at least two vehicles (VA, VB) based on received data messages of the second type (D₂), and

determine whether the service activation criterion is fulfilled based on a situation analysis performed with respect to any received data messages of the first type (D₁) or the second type (D₂).