Auxiliary service cell access method and system, network side element and user equipment

The invention discloses an auxiliary service cell access method which comprises the steps as follows: user equipment (UE) transmits random access preamble or uplink data to a network side through an auxiliary service cell when the uplink authorization is notified by the network side; the network side calculates the time alignment (TA) according to the received access preamble or uplink data and feeds back the time alignment to the user equipment; the user equipment receives and transmits the data in the auxiliary service cell after acquiring the time alignment. The invention also discloses a system for achieving the auxiliary service cell access method, a network side element and the user equipment. With the adoption of the technical scheme of the invention, the user equipment (UE) helps to shorten the time for accessing into the auxiliary service cell, so as to provide high speed business service for the user equipment (UE) as soon as possible. According to the invention, the Scell of the user equipment (UE) can be accessed more rapidly, and the user equipment can be supplied with the Scell access as soon as possible when the business load of the user equipment is heavier.