Transfer of communication sessions between base stations in wireless networks

A method for carrying out an uninterrupted Internet Protocol (IP) communication session with a mobile subscriber terminal through a traffic agent connected to a first IP network, wherein said IP communication session is established in an area serviced by a first base station and continues while said mobile subscriber terminal moves to an area serviced by a second base station, the method comprising:

• at a first network gateway associated with said first base station, selecting a first IP datagram out of a plurality of IP datagrams being part of said communication session with said mobile subscriber terminal;
• prior to establishing a connection between said mobile subscriber terminal and said second base station, carrying out a back up procedure for IP datagrams received at said first network gateway after said first IP datagram had been received thereat and destined to said mobile subscriber terminal;
• and
• upon establishing a connection between said mobile subscriber terminal and another base station out of one or more other base stations, determining said other base station to be a second base station for servicing said mobile subscriber terminal;
• upon determining said second base station:
• refraining from conveying uplink traffic comprising IP datagrams originated by said mobile subscriber terminal, through the first base station;
• forwarding the backed up IP datagrams destined to said mobile subscriber terminal through said second base station;
• and
• forwarding all downlink traffic comprising IP datagrams destined to the mobile subscriber terminal only through said second base station.

In a wireless system comprising a plurality of base stations, at least one network gateway, at least one traffic agent and a mobile subscriber terminal currently communicating with a first base station out of said plurality of base stations communicating with a first network gateway and wherein said first network gateway conveys Internet Protocol (IP) traffic received from said mobile subscriber terminal to the at least one traffic agent and to convey IP traffic received along a packetized network towards said mobile subscriber terminal, a method to enable handover of a communication session that is currently carried by said mobile subscriber terminal through said first base station, by allowing the continuation of said communication session while using a second base station selected out of said plurality of base stations, and comprising:

• transmitting synchronization information from said first base station to said second base station, to enable synchronizing the operation of both said base stations;
• determining a first IP datagram out of a plurality of IP datagrams belonging to said communication session and received at said first network gateway;
• prior to establishing a connection between said mobile subscriber terminal and said second base station, backing up IP datagrams received at said first network gateway after the receipt of said first IP datagram which are destined to the mobile subscriber terminal;
• and
• upon establishing a connection between said mobile subscriber terminal and said second base station, the IP datagrams that were backed up during the back up step and further IP datagrams received at the first network gateway after establishing the connection between the mobile subscriber terminal and the second base station and destined to said mobile subscriber terminal, shall be forwarded to said mobile subscriber terminal through said second base station.

A network gateway operates in a mobile IP wireless network comprising:

• an interface configured to allow communication between said network gateway and a first plurality of base stations associated therewith;
• an interface configured to allow communication between the network gateway and a traffic agent connected to a packetized network;
• at least one processor configured to:
• determine a first IP datagram out of a plurality of received IP datagrams being part of a communication session held with a mobile subscriber terminal through a first base station out of said first plurality of base stations;
• carry a back up procedure for the IP datagrams which follow said first IP datagram and destined to said mobile subscriber terminal before a connection between said mobile subscriber terminal and said second base station has been established;
• and
• in response to receiving a notification that a connection has been established between said mobile subscriber terminal and a base station other than said first base station,
• enable forwarding of said backed up IP datagrams to said mobile subscriber terminal through said other base station;
• enable forwarding of downlink traffic comprising IP datagrams destined to said mobile subscriber terminal only through said other base station;
• and
• preventing from conveying uplink traffic comprising IP datagrams originated by said mobile subscriber terminal, through said first base station.