Method and apparatus for transmitting traffic on overlay and underlay carriers

1. A method of determining which one of an underlay carrier and an overlay carrier is to carry traffic for a wireless call associated with a mobile terminal applied to each of K mobile terminals wherein K is an integer greater or equal to 1 and wherein for a mobile terminal k of the K mobile terminals where k is an integer satisfying k=1 . . . K, the method comprising:

determining a resource parameter associated with a resource for carrying the traffic;

determining a mobility parameter representing a mobility of the mobile terminals that is a function of/correlatable to a speed of the mobile terminal; and

determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter, wherein

determining which of the underlay carrier and the overlay carrier is to carry the traffic comprises using a transfer function T k to determine which of the underlay carrier and the overlay carrier traffic is to carry the traffic for a wireless call associated with the mobile terminal k, wherein

when the wireless call associated with the mobile terminal k is assigned to the underlay carrier, the transfer function T k is given by:

T

k

=

p

k

,

u

H

k

,

p k,u being a forward power on the underlay carrier for the call associated with the mobile terminal k and H k being a probability that the mobile terminal k will require a hard hand-off within a predetermined time, and wherein

wherein the wireless call associated with the mobile terminal k is assigned to the overlay carrier, the transfer function is given by:

T

k

=

p

k

,

o

H

k

p k,o being forward power on the overlay carrier for the wireless call associated with the mobile terminal k.

2. A method according to claim 1 , wherein determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter is done as a function of hard hand-off history information, the hard hand-off history information reflecting a probability of hard hand-off as a function of the mobility parameter, the method further comprising maintaining the hard hand-off history information.

3. A method according to claim 2 wherein determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter is done as a function of hard hand-off history information for a current time frame, the method further comprising maintaining hard hand-off history information for a plurality of time frames, the hard hand-off history reflecting a probability of hard hand-off during each time frame as a function of the mobility parameter.

4. A method according to claim 1 wherein the determining which of the underlay carrier and the overlay carrier is to carry the traffic comprises:

when the wireless call is assigned to the underlay carrier, re-assigning the wireless call to the overlay carrier if the transfer function has a value within a first range of values; and

when the wireless call is assigned to the overlay carrier, re-assigning the wireless call to the underlay carrier if the transfer function has a value within a second range of values.

5. A method of determining which one of an underlay carrier and an overlay carrier is to carry traffic for a wireless call associated with a mobile terminal, the method comprising:

determining a resource parameter associated with a resource for carrying the traffic;

determining a mobility parameter representing a mobility of the mobile terminal that is a function of/correlatable to a speed of the mobile terminal; and

determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter, wherein:

the determining which of the underlay carrier and the overlay carrier carrier is to carry the traffic comprises:

calculating a transfer function as a function of the resource parameter, the mobility parameter, and hard hand-off history information;

when the wireless call is assigned to the underlay carrier, re-assigning the wireless call to the overlay carrier if the transfer function has a value within a first range of values; and

when the wireless call is assigned to the overlay carrier, re-assigning the wireless call to the underlay carrier if the transfer function has a value within a second range of values; and

the resource parameter is a function of a forward power for at least one of the carriers and the transfer function is a function of a ratio of the forward power and a probability of hard hand-off.

6. A method according to claim 5 wherein the overlay carrier is an isolated overlay carrier.

7. A method according to claim 5 wherein the resource parameter is an increasing function of at least one of a forward power, a schedule time, a number of Walsh codes that the mobile terminal occupies, and a delay in transmission.

8. A method according to claim 5 wherein the mobility parameter is correlatable with a likelihood of hand-off.

9. A method according to claim 8 wherein the mobility parameter is a function of/correlatable to at least one of:

a) a location, distance, and a non-radial speed in combination with a direction of travel of the mobile terminal, wherein the speed of the mobile terminal is the non-radial speed; and

b) a radial speed, wherein the speed of the terminal is the radial speed.

10. A method according to claim 5 further comprising maintaining hard hand-off history information for a plurality of time frames.

11. A method according to claim 5 adapted for use with at least two underlay carriers and/or at least two overlay carriers.

12. A method according to claim 11 further comprising:

transmitting traffic on the one of the underlay carrier and the overlay carrier determined and/or receiving traffic on any carrier, time slot or channel associated by duplexing to the one of the underlay carrier and the overlay carrier.

13. The method of claim 5 comprising:

at each of a first plurality of base stations, providing wireless access using the underlay carrier and the overlay carrier;

at each of a second plurality of base stations, providing wireless access using only the underlay carrier;

for a particular base station of the first plurality of base stations, performing said steps of:

determining a resource parameter associated with a resource for carrying the traffic;

determining a mobility parameter representing a mobility of the mobile terminal; and

determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter.

14. An apparatus for carrying traffic for a wireless call associated with a mobile terminal, the apparatus comprising:

a memory for storing instructions;

a processor adapted to, using the instructions;

i) determine a resource parameter associated with a resource for carrying the traffic;

ii) determine a mobility parameter representing a mobility of the mobile terminal that is a function of/correlatable to a seed of the mobile terminal; and

iii) determine which one of an underlay carrier and an overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter; and

a transmitter adapted to transmit the traffic on any one of the underlay carrier and the overlay carrier determined and/or a receiver adapted to receive traffic on any carrier, time slot or channel associated by duplexing to the one of the underlay carrier and the overlay carrier, wherein a capacity to provide the resource for carrying the traffic increases with use of the overlay carrier.

15. An apparatus according to claim 14 wherein to determine which of the underlay carrier and the overlay carrier is to carry the traffic the processor is adapted to determine a transfer function that is a function of the resource parameter and the mobility parameter.

16. An apparatus according to claim 15 wherein to determine which of the underlay carrier and the overlay carrier is to carry the traffic, the processor is adapted to:

when the wireless call is assigned to the underlay carrier, re-assign the wireless call t the overlay carrier if the transfer function has a value within a first range of values; and

when the wireless call is assigned to the overlay carrier, re-assign the wireless call to the underlay carrier if the transfer function has a value within a second range of values.

17. An apparatus according to claim 15 wherein to determine which one of the underlay carrier and the overlay carrier is to carry the traffic, the processor is adapted to:

calculate the transfer function as a function of the resource parameter, the mobility parameter, and hard hand-off history information;

when the wireless call is assigned to the underlay carrier, re-assign the wireless call to the overlay carrier if the transfer function has a value within a first range of values, the first range of values having a first limit defined by a first threshold; and

when the wireless call is assigned to the overlay carrier, re-assign the wireless call to the underlay carrier if the transfer function has a value within a second range of values, the second range of values having a second limit defined by a second threshold.

18. An apparatus according to claim 15 wherein the processor is further adapted to:

maintain hard hand-off history information allowing an estimate of a probability that the mobile terminal will require a hard hand-off within a predetermined time, the hard hand-off history information being maintained as a function of the mobility parameter; and

use the probability to determine the transfer function.

19. An apparatus according to claim 18 wherein the resource parameter is a function of a forward power for at least one of the carriers and the transfer function is a function of a ratio of the forward power and the probability.

20. An apparatus according to claim 14 wherein the overlay carrier is an isolated overlay carrier.

21. An apparatus according to claim 14 wherein the resource parameter is a function of at least one of a forward power, a schedule time, a number of Walsh codes that the mobile terminal occupies, and a delay in transmission.

22. An apparatus according to claim 14 wherein the mobility parameter is a function of/correlatable to at least one of:

a) a location, distance, and a non-radial speed in combination with a direction of travel of the mobile terminal, wherein the speed of the mobile terminal is the non-radial speed; and

b) a radial speed, wherein the speed of the terminal is the radial speed.

23. An apparatus for carrying traffic for a wireless call associated with a mobile terminal, the apparatus comprising:

a memory for storing instructions;

a processor adapted to, using the instructions:

i) determine a resource parameter associated with a resource for carrying the traffic;

ii) determine a mobility parameter representing a mobility of the mobile terminal that is a function of/correlatable to a speed of the mobile terminal; and

iii) determine which one of an underlay carrier and an overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter; and

a transmitter adapted to transmit the traffic on any one of the underlay carrier and the overlay carrier determined and/or a receiver adapted to receive traffic on any carrier, time slot or channel associated by duplexing to the one of the underlay carrier and the overlay carrier, wherein:

to determine which of the underlay carrier and the overlay carrier is to carry the traffic the processor is adapted to determine a transfer function that is a function of the resource parameter and the mobility parameter;

the processor is further adapted to:

maintain hard hand-off history information allowing an estimate of a probability that the mobile terminal will require a hard hand-off within a predetermined time, the hard hand-off history information being maintained as a function of the mobility parameter; and

use the probability to determine the transfer function;

the resource parameter is a function of a forward power for at least one of the carriers and the transfer function is a function of a ration of the forward power and the probability; and

the processor is adapted to determine a resource parameter associated with a resource for carrying the traffic, and to determine a mobility parameter representing a mobility of the mobile terminal, and to determine which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter for each of K mobile terminals wherein K is an integer greater or equal to 1.

24. An apparatus according to claim 23 wherein the processor is adapted to use a transfer function T k to determine which of the underlay carrier and the overlay carrier traffic from a wireless call associated with the mobile terminal k is to be carried on;

wherein when the wireless call associated with the mobile terminal k is assigned to the underlay carrier, the transfer function T k is given by:

T

k

=

p

k

,

u

H

k

,

p k,u being a forward power on the underlay carrier for the call associated with the mobile terminal k and H k being a probability that the mobile terminal k will require a hard hand-off within a predetermined time; and

wherein when the wireless call associated with the mobile terminal k is assigned to the overlay carrier, the transfer function is given by:

T

k

=

p

k

,

o

H

k

p k,o being a forward power on the overlay carrier for the wireless call associated with the mobile terminal k.

25. A base station comprising the apparatus of claim 23 and further comprising:

a receiver adapted to receive information associated with the resource parameter and/or the mobility parameter.

26. A base station comprising the apparatus of claim 23 further adapted to collect information associated with the resource parameter from within the base station.

27. A computer readable medium having computer readable program code means embodied therein for determining which one of an underlay carrier and an overlay carrier is to carry traffic for a wireless call associated with a mobile terminal, the computer readable code means in said article of manufacture comprising:

computer readable code means for determining a resource parameter associated with a resource for transmitting the traffic;

computer readable code means for determining a mobility parameter representing a mobility of the mobile terminal that is a function of/correlatable to a speed of the mobile terminal; and

computer readable code means for determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter, wherein:

the computer readable code means for determining which of the underlay carrier and the overlay carrier is to carry the traffic comprises:

computer readable code means for calculating a transfer function as a function of the resource parameter, the mobility parameter and hard hand-off history information;

computer readable code means for when the wireless call is assigned to the underlay carrier, re-assigning the wireless call to the overlay carrier if the transfer function has a value within a first range of values; and

computer readable code means for when the wireless call is assigned to the overlay carrier, re-assigning the wireless call to the underlay carrier if the transfer function has a value within a second range of values; and

the resource parameter is a function of a forward power for at least one of the carriers and the transfer function is a function of a ration of the forward power and a probability of hard hand-off.

28. A method of determining which one of an underlay carrier and an overlay carrier is to carry traffic for a wireless call associated with a mobile terminal, the method comprising:

determining a resource parameter associated with a resource for carrying the traffic;

determining a mobility parameter representing a mobility of the mobile terminal that is a function of/correlatable to a speed of the mobile terminal; and

determining which of the underlay carrier and the overlay carrier is to carry the traffic as a function of the resource parameter and the mobility parameter, wherein:

the determining which of the underlay carrier and the overlay carrier is to carry the traffic comprises:

calculating a transfer function as a function of the resource parameter, the mobility parameter, and hard hand-off history information;

where the wireless call is assigned to the underlay carrier, re-assigning the wireless call to the overlay carrier if the transfer function has a value within a first range of values; and

when the wireless call is assigned to the overlay carrier, re-assigning the wireless call to the underlay carrier if the transfer function has a value within a second range of values; and

the first range of values and the second range of values are selected to avoid rapid alternation between the underlay carrier and the overlay carrier.