Transfer of communication sessions between base stations in wireless networks

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 stations out of said plurality of base stations communicating with a first network gateway and wherein said first network gateway is adapted to convey 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 continuing a communication session that is currently carried by said mobile subscriber terminal through said first base station, through using a second base station out of said plurality of base stations, and comprising:

• during a communication session held with the mobile subscriber terminal, determining a first IP datagram out of a plurality of IP datagrams associated with said communication session and received at said first network gateway;
• backing up IP datagrams received at said first network gateway after that first IP datagram and addressed to the mobile subscriber terminal;
• and
• upon establishing a connection between said mobile subscriber terminal and said second base station, the first base station would cease to convey uplink traffic originated by the mobile subscriber terminal, the IP datagrams that were backed up during the back up step will be forwarded to the mobile subscriber terminal, and all further IP datagrams addressed to said mobile subscriber terminal and received at the first network gateway after establishing the connection between the mobile subscriber terminal and the second base station, will be forwarded to the mobile subscriber terminal through said second base station.

A method for carrying out an uninterrupted IP communication session with a mobile subscriber terminal through a traffic agent connected to an 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 addressed to said mobile subscriber terminal;
• carrying out a back up procedure for IP datagrams received at said first network gateway which proceeds said first IP datagram 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 another 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.

A network gateway adapted to operate in a mobile IP wireless network and comprising:

• an interface operative to allow communication between said network gateway and a first plurality of base stations associated therewith;
• an interface operative to allow communication between the network gateway and a traffic agent connected to a packetized network;
• at least one processor adapted to:
• determine a first IP datagram out of a plurality of received IP datagrams associated with 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;
• 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.

A base station adapted to operate in a mobile IP wireless network and comprising:

• an interface operative to allow communication between at least one other base station and a at least one mobile subscriber terminal;
• at least one processor adapted to:
• forward 802.16 MAC synchronization information to said at least one other base station required for synchronizing the operation of both said base stations;
• receive confirmation that the operation of said both base stations has been synchronized;
• cease to convey uplink traffic originated by said at least one mobile subscriber terminal.