Method and apparatus for improving mobility states of a user equipment group in a wireless communication system

1. A method performed by a user equipment (UE) for managing a mobility state in a mobile communication system, the method comprising:

receiving, from a base station (BS), parameters including information determining a group mobility state;

assigning a plurality of UEs to a group of UEs, wherein the UE is identified as a lead UE;

determining whether a number of cell reselections during time period T CRmax,Group exceeds N CR_H,Group ;

configuring the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds N CR_H,Group , or the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed N CR_H,Group ;

receiving a speed dependent scaling factor T reselection for the group mobility state; and

informing, by the lead UE, the group mobility state and the speed dependent scaling factor T reselection to the group of UEs.

2. The method of claim 1 wherein the group of UEs is a platoon.

3. The method of claim 2 , further comprising using a communication channel that is a different communication channel used for the BS.

4. The method of claim 3 , wherein a short range communication comprises a direct vehicle to vehicle (V2V) interface is used to communicate the group mobility state to the group of UEs in the platoon.

5. The method of claim 1 , further comprising:

determining whether a number of cell reselections exceeds a first predefined threshold; and

determining the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds the first predefined threshold.

6. The method of claim 5 , further comprising determining the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed the first predefined threshold.

7. A method performed by a base station (BS) for managing a mobility state in a mobile communication system, the method comprising:

assigning a plurality of user equipments (UEs) to a group of UEs, wherein one of the plurality of UEs is identified as a lead UE;

transmitting, to the lead UE, parameters including information determining a group mobility state; and

transmitting a speed dependent scaling factor T reselection for the group mobility state,

wherein:

the group mobility state is determined as a group high mobility state based on a determination that a number of cell reselections exceeds N CR_H,Group , or the group mobility state is determined as a group medium mobility state based on a determination that the number of cell reselections does not exceed N CR_H,Group , and

the group mobility state and the speed dependent scaling factor T reselection are informed, by the lead UE, to the group of UEs.

8. The method of claim 7 , wherein the group of UEs is a platoon.

9. The method of claim 8 , wherein a communication channel used for the group mobility state is a different than a communication channel that is used to communicate between the lead UE and the plurality of UEs.

10. The method of claim 9 , wherein a short range communication comprises a direct vehicle to vehicle (V2V) interface is used to communicate group mobility state to the group of UEs in the platoon.

11. The method of claim 7 , further comprising:

determining whether a number of cell reselections exceeds a first predefined threshold; and

determining the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds the first predefined threshold.

12. The method of claim 11 , further comprising determining the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed the first predefined threshold.

13. A user equipment (UE) comprising:

a transceiver configured to receive, from a base station (BS), parameters including information determining a group mobility state; and

a processor operably coupled to the transceiver, the processor configured to:

assign a plurality of UEs to a group of UEs, wherein the UE is identified as a lead

determine whether a number of cell reselections during time period T CRMax,Group exceeds N CR_H,Group ,

configure the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds N CR_H,Group , or the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed N CR_H,Group ,

receive a speed dependent scaling factor T reselection for the group mobility state, and

inform, by the lead UE, the group mobility state and the speed dependent scaling factor T reselection to the group of UEs.

14. The UE of claim 13 , wherein the group of UEs is a platoon.

15. The UE of claim 14 , wherein the processor is further configured to communicate to the group mobility state, and wherein a communication channel used for the group mobility state is different than a communication channel that is used to communicate with the BS.

16. The UE of claim 15 , wherein the transceiver is further configured to perform a short range communication comprising a direct vehicle to vehicle (V2V) interface that is used to communicate the group mobility state to the group of UEs in the platoon.

17. The UE of claim 13 , wherein the processor is further configured to:

determine whether a number of cell reselections exceeds a first predefined threshold, and

determine the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds the first predefined threshold.

18. The UE of claim 17 , wherein the processor is further configured to determine the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed the first predefined threshold.

19. A base station (BS) comprising:

a transceiver configured to transmit parameters including information determining a group mobility state; and

a processor operably coupled to the transceiver, the processor configured to:

assign a plurality of user equipments (UEs) to a group of UEs, wherein one of the plurality of UEs is identified as a lead UE, and

transmit a speed dependent scaling factor T reselection for the group mobility state,

wherein:

the group mobility state is determined as a group high mobility state based on a determination that a number of cell reselections exceeds N CR_H,Group , or the group mobility state is determined as a group medium mobility state based on a determination that the number of cell reselections does not exceed N CR_H,Group , and

the group mobility state and the speed dependent scaling factor T reselection , are informed by the lead UE, to the group of UEs.

20. The BS of claim 19 , wherein the processor is further configured to:

determine whether a number of cell reselections exceeds a first predefined threshold;

determine the group mobility state as a group high mobility state based on a determination that the number of cell reselections exceeds the first predefined threshold; and

determine the group mobility state as a group medium mobility state based on a determination that the number of cell reselections does not exceed the first predefined threshold.