System and method for performing soft handoff in a wireless data network

A method for performing handoff of mobile wireless user terminals between access points on a packet-switched core network in a communications network, each said access point being adapted to provide any said user terminal with communications access to said core network when said any user terminal becomes affiliated with said access point, and including an address resolution cache which is adapted to store information representative of affiliation between said user terminals and said access points, the method comprising:

• when a said user terminal changes its affiliation from a first said access point to a second said access point, controlling an other node on said core network other than said first and second access points to continue to send data packets intended for receipt by said user terminal to said first access point until having updated its respective address resolution cache based on a message indicating that a said user terminal has changed its affiliation from said first access point to said second access point;
• and
• while said other node continues to send said data packets to said first access point, controlling said first access point to continue to send said data packets received from said other node to said user terminal without sending said data packets to said second access point,
• wherein when said user terminal changes its affiliation from a first said access point to a second said access point, controlling an additional node other than said first and second access points and said other node to send data packets intended for receipt by said user terminal to said second access point after having updated its respective address resolution cache based on said message while said other node continues to send data packets intended for said user terminal to said first access point which continues to send said data packets received from said other node to said user terminal without sending said data packets to said second access point.

A computer-readable medium of instructions for controlling a communications network having access points on a packet-switched core network to perform handoff of mobile wireless user terminals between said access points, each said access point being adapted to provide any said user terminal with communications access to said core network when said any user terminal becomes affiliated with said access point, and including an address resolution cache which is adapted to store information representative of affiliation between said user terminals and said access points, the computer-readable medium of instructions comprising:

• a first set of instructions which, when a said user terminal changes its affiliation from a first said access point to a second said access point, is adapted to control an other node on said core network other than said first and second access points to continue to send data packets intended for receipt by said user terminal to said first access point until having updated its respective address resolution cache based on a message indicating that a said user terminal has changed its affiliation from said first access point to said second access point;
• a second set of instructions which, while said other node continues to send said data packets to said first access point, is adapted to control said first access point to continue to send said data packers received from said other node to said user terminal without sending said data packets to said second access point, and
• a third set of instructions which, when said user terminal changes its affiliation from a first said access point to a second said access point, is adapted to control an additional node other than said first and second access points and said other node to send data packets intended for receipt by said user terminal to said second access point after having updated its respective address resolution cache based on said message while said other node continues to send data packets intended for said user terminal to said first access point which continues to send said data packets received from said other node to said user terminal without sending said data packets to said second access point.