Handover random access
Systems, apparatuses, and methods are described for wireless communications. Random access procedures may include various types of procedures, such as 4-step or 2-step random access procedures. One or more indicators may be included in one or more messages for a handover to indicate a type of a random access procedure.
1. A method comprising:
receiving, by a wireless device and from a base station associated with a first cell, a message comprising a command for a handover to a second cell, wherein the message is indicative of a type of a random access procedure for the handover; and
transmitting, by the wireless device and for the handover to the second cell, a random access preamble employing the type of the random access procedure.
2. The method of claim 1 , further comprising transmitting, by the wireless device, one or more transport blocks overlapping in time with the random access preamble.
3. The method of claim 2 , wherein the one or more transport blocks comprise one or more of:
a handover complete message;
uplink data;
a buffer status report; or
an identifier of the wireless device.
4. The method of claim 1 , wherein the message comprises, for the random access procedure, one or more of:
a preamble identifier; or
random access resource information.
5. The method of claim 1 , wherein the message comprises:
timing advance information for transmission of one or more of: the random access preamble or one or more transport blocks.
6. The method of claim 1 , wherein the second cell is a cell of one or more second cells, and wherein the method further comprises:
receiving, via the one or more second cells, one or more second messages comprising one or more of:
an indication of a power associated with a cell;
an indication of a quality associated with a cell; or
an indication of a cell priority; and
transmitting, based on the one or more second messages, a measurement report.
7. The method of claim 1 , wherein the message comprises one or more parameters indicating the type of the random access procedure.
8. The method of claim 1 , wherein the message comprises a preamble identifier, and wherein the method further comprises:
determining, based on the preamble identifier, radio resources associated with the random access procedure.
9. The method of claim 1 , wherein the message comprises:
random access channel configuration information for a two-step random access procedure; and
radio resource configuration parameters for the two-step random access procedure.
10. The method of claim 1 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
11. The method of claim 1 , wherein the message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
12. A method comprising:
transmitting, by a base station associated with a first cell, a first message indicative of a handover to a second cell;
receiving, by the base station, a second message indicative of a type of a random access procedure for the handover; and
transmitting, by the base station, a third message indicative of the type of the random access procedure.
13. The method of claim 12 , wherein:
the receiving the second message comprises receiving the second message from a second base station associated with the second cell; and
the second message comprises a handover request.
14. The method of claim 12 , wherein:
the receiving the second message comprises receiving the second message from a core network device; and
the second message indicates that the handover is requested.
15. The method of claim 12 , wherein the first message indicates that the handover is requested, and wherein the method further comprises:
transmitting, to a second base station, and based on the first message, a fourth message comprising a handover request; and
receiving, from the second base station, a fifth message indicating the type of the random access procedure for the handover and comprising an acknowledgement of the handover request.
16. The method of claim 12 , wherein the third message comprises, for the random access procedure, one or more of:
a preamble identifier; or
random access resource information.
17. The method of claim 12 , wherein the third message comprises timing advance information for transmission, by a wireless device, of one or more of: a random access preamble or one or more transport blocks.
18. The method of claim 17 , wherein the timing advance information comprises one or more of:
an indication of a zero timing advance; or
a value for a timing advance.
19. The method of claim 12 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
20. The method of claim 12 , wherein the third message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
21. A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
receive, from a base station associated with a first cell, a message comprising a command for a handover to a second cell, wherein the message is indicative of a type of a random access procedure for the handover; and
transmit, for the handover to the second cell, a random access preamble employing the type of the random access procedure.
22. The wireless device of claim 21 , wherein the message comprises:
timing advance information for transmission of one or more of: the random access preamble or one or more transport blocks.
23. The wireless device of claim 21 , wherein the second cell is a cell of one or more second cells, and wherein the instructions, when executed by the one or more processors, further cause the wireless device to:
receive, via the one or more second cells, one or more second messages comprising one or more of:
an indication of a power associated with a cell;
an indication of a quality associated with a cell; or
an indication of a cell priority; and
transmit, based on the one or more second messages, a measurement report.
24. The wireless device of claim 21 , wherein the message comprises a preamble identifier, and wherein the instructions, when executed by the one or more processors, further cause the wireless device to:
determine, based on the preamble identifier, radio resources associated with the random access procedure.
25. The wireless device of claim 21 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
26. The wireless device of claim 21 , wherein the message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
27. A base station associated with a first cell, the base station comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the base station to:
transmit a first message indicative of a handover to a second cell;
receive a second message indicative of a type of a random access procedure for the handover; and
transmit a third message indicative of the type of the random access procedure.
28. The base station of claim 27 , wherein the instructions, when executed by the one or more processors, cause the base station to:
receive the second message from a second base station associated with the second cell, wherein the second message comprises a handover request.
29. The base station of claim 27 , wherein the instructions, when executed by the one or more processors, cause the base station to:
receive the second message from a core network device, wherein the second message indicates that the handover is requested.
30. The base station of claim 27 , wherein the first message indicates that the handover is requested, and wherein the instructions, when executed by the one or more processors, further cause the base station to:
transmit, to a second base station, and based on the first message, a fourth message comprising a handover request; and
receive, from the second base station, a fifth message indicating the type of the random access procedure for the handover and comprising an acknowledgement of the handover request.
31. The base station of claim 27 , wherein the third message comprises timing advance information for transmission, by a wireless device, of one or more of: a random access preamble or one or more transport blocks.
32. The base station of claim 31 , wherein the timing advance information comprises one or more of:
an indication of a zero timing advance; or
a value for a timing advance.
33. The base station of claim 27 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
34. The base station of claim 27 , wherein the third message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
35. A non-transitory computer-readable medium storing instructions that, when executed, configure a wireless device to:
receive, from a base station associated with a first cell, a message comprising a command for a handover to a second cell, wherein the message is indicative of a type of a random access procedure for the handover; and
transmit, for the handover to the second cell, a random access preamble employing the type of the random access procedure.
36. The non-transitory computer-readable medium of claim 35 , wherein the message comprises:
timing advance information for transmission of one or more of: the random access preamble or one or more transport blocks.
37. The non-transitory computer-readable medium of claim 35 , wherein the second cell is a cell of one or more second cells, and wherein the instructions, when executed, further configure the wireless device to:
receive, via the one or more second cells, one or more second messages comprising one or more of:
an indication of a power associated with a cell;
an indication of a quality associated with a cell; or
an indication of a cell priority; and
transmit, based on the one or more second messages, a measurement report.
38. The non-transitory computer-readable medium of claim 35 , wherein the message comprises a preamble identifier, and wherein the instructions, when executed, further configure the wireless device to:
determine, based on the preamble identifier, radio resources associated with the random access procedure.
39. The non-transitory computer-readable medium of claim 35 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
40. The non-transitory computer-readable medium of claim 35 , wherein the message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
41. A non-transitory computer-readable medium storing instructions that, when executed, configure a base station to:
transmit a first message indicative of a handover to a second cell, wherein the base station is associated with a first cell;
receive a second message indicative of a type of a random access procedure for the handover; and
transmit a third message indicative of the type of the random access procedure.
42. The non-transitory computer-readable medium of claim 41 , wherein the instructions, when executed, configure the base station to:
receive the second message from a second base station associated with the second cell, wherein the second message comprises a handover request.
43. The non-transitory computer-readable medium of claim 41 , wherein the instructions, when executed, configure the base station to:
receive the second message from a core network device, wherein the second message indicates that the handover is requested.
44. The non-transitory computer-readable medium of claim 41 , wherein the first message indicates that the handover is requested, and wherein the instructions, when executed, further configure the base station to:
transmit, to a second base station, and based on the first message, a fourth message comprising a handover request; and
receive, from the second base station, a fifth message indicating the type of the random access procedure for the handover and comprising an acknowledgement of the handover request.
45. The non-transitory computer-readable medium of claim 41 , wherein the third message comprises timing advance information for transmission, by a wireless device, of one or more of: a random access preamble or one or more transport blocks.
46. The non-transitory computer-readable medium of claim 45 , wherein the timing advance information comprises one or more of:
an indication of a zero timing advance; or
a value for a timing advance.
47. The non-transitory computer-readable medium of claim 41 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
48. The non-transitory computer-readable medium of claim 41 , wherein the third message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.
49. A system comprising:
a base station associated with a first cell, the base station comprising:
one or more processors; and
memory storing instructions; and
a wireless device comprising:
one or more processors; and
memory storing instructions,
wherein the instructions stored in the memory of the base station, when executed by the one or more processors of the base station, cause the base station to:
transmit a first message indicative of a handover to a second cell;
receive a second message indicative of a type of a random access procedure for the handover; and
transmit a third message indicative of the type of the random access procedure, and
wherein the instructions stored in the memory of the wireless device, when executed by the one or more processors of the wireless device, cause the wireless device to:
receive the third message; and
transmit, for the handover to the second cell, a random access preamble employing the type of the random access procedure.
50. The system of claim 49 , wherein the instructions stored in the memory of the base station, when executed by the one or more processors of the base station, cause the base station to:
receive the second message from a second base station associated with the second cell, wherein the second message comprises a handover request.
51. The system of claim 49 , wherein the instructions stored in the memory of the base station, when executed by the one or more processors of the base station, cause the base station to:
receive the second message from a core network device, wherein the second message indicates that the handover is requested.
52. The system of claim 49 , wherein the first message indicates that the handover is requested, and wherein the instructions stored in the memory of the base station, when executed by the one or more processors of the base station, further cause the base station to:
transmit, to a second base station, and based on the first message, a fourth message comprising a handover request; and
receive, from the second base station, a fifth message indicating the type of the random access procedure for the handover and comprising an acknowledgement of the handover request.
53. The system of claim 49 , wherein the third message comprises timing advance information, and wherein the instructions stored in the memory of the wireless device, when executed by the one or more processors of the wireless device, cause the wireless device to transmit the random access preamble using the timing advance information.
54. The system of claim 53 , wherein the timing advance information comprises one or more of:
an indication of a zero timing advance; or
a value for a timing advance.
55. The system of claim 49 , wherein the type of the random access procedure for the handover is one of a two-step random access procedure or a four-step random access procedure.
56. The system of claim 49 , wherein the third message is indicative of the type of the random access procedure for the handover being one of a contention free random access procedure, a contention based random access procedure, or a contention free two-step random access procedure.