Base station based methods and apparatus for supporting break before make handoffs in a multi-carrier system

A method of operating a second network attachment point in a communications system including a first network attachment point, the first network attachment point using signals in a first frequency band to communicate with a mobile node having a communications link with said first network point of attachment over which data can be communicated, the method comprising:

• transmitting beacon signals having a predetermined frequency into said first frequency band on a recurring basis, said first frequency band being a frequency band into which said second network attachment point does not transmit user data;
• and
• using a second frequency band which is different from said first frequency band for establishing and maintaining communications links with mobile nodes, said step of using a second frequency band including assigning segments or an uplink communications channel to mobile nodes, the uplink communications channel having a structure that includes a repeating pattern of access segments and traffic segments, access segments being segments into which mobile nodes that do not have an existing wireless communication link established with said second network attachment point can send at least one signal to said second network attachment point over the air to establish a wireless communications link with the second network attachment point, access segments having a predetermined time offset relationship to beacon signals that are transmitted into said first frequency band by said second network attachment point;
• receiving a signal indicating that said mobile node is seeking to perform a handoff from said first network attachment point to said second network attachment point;
• dedicating a first set of tones in a first access segment to said mobile node which is coupled to said first network attachment point;
• communicating information to the first mobile node via the first network attachment point indicating the dedication of said first set of tones to the mobile node;
• monitoring the first set of tones in the first access segment for a registration signal from the mobile node to which said first access segment was assigned;
• and
• receiving a registration signal from the mobile node which was communicated using said dedicated first set of tones.

A method of operating a second base station to perform a mobile node handoff operation involving a handoff of a mobile node from a first base station having a first communications link with said mobile node, the method comprising:

• allocating a dedicated resource, said dedicated resource including at least a dedicated set of uplink tones to be used by said mobile node for a period of time when performing a timing synchronization operation as part of establishing a second communications link with said second base station, said dedicated set of uplink tones being less than a full set of tones available for uplink signaling to said second base station during said period of time;
• transmitting information about the dedicated resource to said first base station by a communications link between said first and second base stations;
• receiving a timing control signal over the air from said mobile node on said uplink tones dedicated to said mobile node by said second base station;
• and
• transmitting to said mobile node, after receiving said timing control signal, a timing synchronization signal, prior to receiving user data from said mobile node.

A method of operating a second base station to perform a mobile node handoff operation involving a handoff of a mobile node from a first base station having a first communications link with said mobile node, the method comprising:

• transmitting high power narrowband signals on a periodic basis;
• allocating a dedicated resource to be used by said mobile node when establishing a second communications link with said second base station;
• transmitting dedicated resource information to said first base station by a communications link between said first and second base stations;
• communicating to said first base station information indicating a point in time said mobile node should register over the air with said second base station, said point in time having a fixed relationship to the time at which said second base station transmits at least one of said high power narrowband signals;
• receiving a timing control signal over the air from said mobile node in an uplink communications segment dedicated to said mobile node by said second base station;
• and
• transmitting to said mobile node, after receiving said timing control signal, a timing synchronization signal, prior to receiving user data from said mobile node.

A method of operating a second base station to perform a mobile node handoff operation involving a handoff of a mobile node from a first base station having a first communications link with said mobile node, the method comprising:

• allocating a dedicated resource to be used by said mobile node when establishing a second communications link with said second base station;
• transmitting information about the dedicated resource to said first base station by a communications link between said first and second base stations;
• receiving a timing control signal over the air from said mobile node in an uplink communications segment dedicated to said mobile node by said second base station;
• and
• transmitting to said mobile node, after receiving said timing control signal, a timing synchronization signal, prior to receiving user data from said mobile node;
• and
• wherein said second base station begins receiving IP packets directed to said mobile node from other network nodes, after transmitting said dedicated resource information to said mobile node and prior to transmitting said timing synchronization signal to said mobile node.

A second base station capable of performing mobile node handoff operations involving a handoff of a mobile node from a first base station having a first communications link with said mobile node to said second base station, the second base station comprising:

• means for allocating a dedicated resource including a set of uplink tones to be used by said mobile node when establishing a second communications link with said second base station, said set of uplink tones being less than a full set of uplink tones which are used for communicating signals to said second base station;
• means for transmitting information about the dedicated resource to said first base station over a communications link between said first and second base stations;
• means for receiving, on said dedicated set of uplink tones, a registration signal communicated over the air from said mobile node to said second base station;
• and
• means for transmitting to said mobile node, after receiving said registration signal, a timing synchronization signal, prior to receiving user data from said mobile node.

A second base station capable of performing mobile node handoff operations involving a handoff of a mobile node from a first base station having a first communications link with said mobile node to said second base station, the second base station comprising:

• means for allocating a dedicated resource to be used by said mobile node when establishing a second communications link with said second base station;
• means for transmitting information about the dedicated resource to said first base station on a communications link between said first and second base stations;
• means for receiving a registration signal over the air from said mobile node;
• means for transmitting to said mobile node, after receiving said registration signal, a timing synchronization signal, prior to receiving user data from said mobile node;
• means for transmitting high power narrowband signals on a periodic basis;
• and
• means for communicating to said first base station information indicating a point in time said mobile node should register over the air with said second base station, said point in time having a fixed relationship to the time at which said second base station transmits at least one of said high power narrowband signals.

A second base station capable of performing mobile node handoff operations involving a handoff of a mobile node from a first base station having a first communications link with said mobile node to said second base station, the second base station comprising:

• means for allocating a dedicated resource to be used by said mobile node when establishing a second communications link with said second base station;
• means for transmitting information about the dedicated resource to said first base station over a communications link between said first and second base stations;
• means for receiving a registration signal over the air from said mobile node;
• and
• means for transmitting to said mobile node, after receiving said registration signal, a timing synchronization signal, prior to receiving user data from said mobile node;
• and
• wherein said second base station begins receiving IP packets directed to said mobile node from other network nodes, after transmitting said dedicated resource information to said mobile node and prior to transmitting said timing synchronization signal to said mobile node.

A method of operating a base station to implement a mobile node handoff between a first communications link with a first base station sector, said first communications link using a first carrier, and a second communications link with a second base station sector said second communications link using a second carrier, the first and second sectors being within the same base station, at least the first sector being different from the second sector or the first carrier being different from the second carrier, the method comprising:

• operating receivers in said first and second sectors corresponding to said first and second carriers, respectively, to operate in a timing synchronized manner;
• transmitting a timing correction signal to said mobile node over said first communications link;
• receiving from the mobile node a signal communicated over said first communications link indicating an intent to handoff to said second communications link;
• transmitting over said first communications link information indicating a dedicated resource to be used by said mobile when communicating over said second communications link;
• terminating said first communications link with said mobile node;
• and
• receiving from said mobile node at least one off user data and a non-timing control signal over said second communications link prior to transmitting a transmission timing control adjustment signal generated based on any timing control signal received over said second communications link from said mobile node.