A method for performing a handoff by a telecommunication system comprising: Step I: performing a first multi-cell joint detection process for decoding for communications within a home cell when a mobile terminal enters a border area between the home cell and one or more neighboring cells (C2, C3), the joint detection refers to a combined operation of matched filtering and Multiple Access Interference, MAI, - Inter-Symbol Interference, ISI, elimination; Step II: performing a handoff process for the mobile terminal when in the home cell to join a target neighboring cell; and Step III: performing a second multi-cell joint detection process for decoding for the communications between the mobile terminal and the target neighboring cell after the handoff process is performed, characterized in that performing the first multi-cell joint detection process includes: performing a multi-cell channel estimation to obtain pilot channel estimation codes for both the home cell and the one or more neighboring cells (C2, C3); selecting code channels from the one or more neighboring cells (C2, C3) based on a boundary of the home cell and a code channel power intensity of the one or more neighboring cells (C2, C3), comprising: selecting the code channels from the neighboring cells (C2, C3) if the intensity of the interference signal or SNR from the corresponding neighboring cell is above a first predetermined threshold; grouping the selected code channels to obtain a code channel grouping result based on a predetermined arrangement, selected to designate different code channels for neighboring cells (C2, C3), between the code channels and the pilot channel estimation codes of the home cell and the neighboring cells (C2, C3); and performing the first multi-cell joint detection process based on the pilot channel estimation codes of the home cell and the one or more neighboring cells (C2, C3) and the code channel grouping result. Step I: performing a first multi-cell joint detection process for decoding for communications within a home cell when a mobile terminal enters a border area between the home cell and one or more neighboring cells (C2, C3), the joint detection refers to a combined operation of matched filtering and Multiple Access Interference, MAI, - Inter-Symbol Interference, ISI, elimination; Step II: performing a handoff process for the mobile terminal when in the home cell to join a target neighboring cell; and Step III: performing a second multi-cell joint detection process for decoding for the communications between the mobile terminal and the target neighboring cell after the handoff process is performed, characterized in that performing the first multi-cell joint detection process includes: performing a multi-cell channel estimation to obtain pilot channel estimation codes for both the home cell and the one or more neighboring cells (C2, C3); selecting code channels from the one or more neighboring cells (C2, C3) based on a boundary of the home cell and a code channel power intensity of the one or more neighboring cells (C2, C3), comprising: selecting the code channels from the neighboring cells (C2, C3) if the intensity of the interference signal or SNR from the corresponding neighboring cell is above a first predetermined threshold; grouping the selected code channels to obtain a code channel grouping result based on a predetermined arrangement, selected to designate different code channels for neighboring cells (C2, C3), between the code channels and the pilot channel estimation codes of the home cell and the neighboring cells (C2, C3); and performing the first multi-cell joint detection process based on the pilot channel estimation codes of the home cell and the one or more neighboring cells (C2, C3) and the code channel grouping result. performing a multi-cell channel estimation to obtain pilot channel estimation codes for both the home cell and the one or more neighboring cells (C2, C3); selecting code channels from the one or more neighboring cells (C2, C3) based on a boundary of the home cell and a code channel power intensity of the one or more neighboring cells (C2, C3), comprising: selecting the code channels from the neighboring cells (C2, C3) if the intensity of the interference signal or SNR from the corresponding neighboring cell is above a first predetermined threshold; grouping the selected code channels to obtain a code channel grouping result based on a predetermined arrangement, selected to designate different code channels for neighboring cells (C2, C3), between the code channels and the pilot channel estimation codes of the home cell and the neighboring cells (C2, C3); and performing the first multi-cell joint detection process based on the pilot channel estimation codes of the home cell and the one or more neighboring cells (C2, C3) and the code channel grouping result.