A method performed by a user equipment, the method comprising: receiving an indication of a set of semi-statically configured random access channel resources via a higher layer signaling, where the higher layer is higher than a physical layer; receiving an indication of availability of a random access channel resource of at least one random access channel resource of the set of semi-statically configured random access channel resources via a dynamic physical-layer signaling, where the dynamic physical-layer signaling is within a number of slots including a random access channel slot, wherein the random access channel slot includes the at least one random access channel resource of the set of semi-statically configured random access channel resources; determining an available random access channel resource in the random access channel slot based on the received indication of the set of semi-statically configured random access channel resources and based on the received indication of availability of the random access channel resource of the at least one random access channel resource of the set of semi-statically configured random access channel resources; and transmitting a random access channel preamble on the available random access channel resource in the random access channel slot; wherein the set of semi-statically configured random access channel resources is a first set of semi-statically configured random access channel resources for a serving cell, characterized by the method further comprises receiving an indication of a second set of semi-statically configured random access channel resources for a handover target cell, where the indication of a second set of semi-statically configured random access channel resources is received in a handover command message, wherein the second set of semi-statically configured random access channel resources is different from a third set of semi-statically configured random access channel resources for at least one random access channel resource, and wherein the third set of semi-statically configured random access channel resources is broadcasted in a system information block of the handover target cell. receiving an indication of a set of semi-statically configured random access channel resources via a higher layer signaling, where the higher layer is higher than a physical layer; receiving an indication of availability of a random access channel resource of at least one random access channel resource of the set of semi-statically configured random access channel resources via a dynamic physical-layer signaling, where the dynamic physical-layer signaling is within a number of slots including a random access channel slot, wherein the random access channel slot includes the at least one random access channel resource of the set of semi-statically configured random access channel resources; determining an available random access channel resource in the random access channel slot based on the received indication of the set of semi-statically configured random access channel resources and based on the received indication of availability of the random access channel resource of the at least one random access channel resource of the set of semi-statically configured random access channel resources; and transmitting a random access channel preamble on the available random access channel resource in the random access channel slot; wherein the set of semi-statically configured random access channel resources is a first set of semi-statically configured random access channel resources for a serving cell, characterized by the method further comprises receiving an indication of a second set of semi-statically configured random access channel resources for a handover target cell, where the indication of a second set of semi-statically configured random access channel resources is received in a handover command message, wherein the second set of semi-statically configured random access channel resources is different from a third set of semi-statically configured random access channel resources for at least one random access channel resource, and wherein the third set of semi-statically configured random access channel resources is broadcasted in a system information block of the handover target cell.