System and method for effecting information transmission and soft handoff between frequency division duplex and time division duplex communications systems

A method for controlling mobile unit communication handoffs from a frequency division duplex (FDD) communication system to a time division duplex (TDD) communications system, wherein the mobile unit is transmitting information via the FDD communications system, the method comprising:

• generating a pilot search signal corresponding to a transmission range of the TDD communication system;
• initiating the communication handoff from the FDD communication system to the TDD communication system when the mobile unit recognizes a predetermined threshold level of the pilot search signal;
• synchronizing concurrent communications between the mobile unit to both the FDD and TDD communications systems;
• transmitting the information in a multirate mode upon acknowledgment of the synchronization by the TDD communication system, including communicating the information with the FDD communication system at an increased FDD data rate in the uplink frame between the mobile unit and the FDD communications system, and communicating the information with the TDD communication system at an increased TDD data rate in a remaining portion of the uplink frame between the mobile unit and the TDD communications system;
• and
• terminating transmission between the mobile unit and the FDD communication system and maintaining communication between the mobile unit and the TDD communication system when the synchronization is complete.

A method for controlling mobile unit communication handoffs from a time duplex (TDD) communication system to a frequency division duplex (FDD) communications system, wherein the mobile unit is transmitting information via the TDD communications system, the method comprising:

• generating a pilot search signal corresponding to a transmission range of the FDD communication system;
• initiating the communication handoff from the TDD communication system to the FDD communication system when the mobile unit recognizes a predetermined threshold level of the pilot search signal;
• synchronizing concurrent communications between the mobile unit to both the TDD and FDD communications systems;
• transmitting the information in a multirate mode upon acknowledgment of the synchronization by the FDD communication system, including communicating the information with the TDD communication system at an increased TDD data rate in the uplink frame between the mobile unit and the TDD communications system, and communicating the information with the FDD communication system at an increased FDD data rate in a remaining portion of the uplink frame between the mobile unit and the FDD communications system;
• and
• terminating transmission between the mobile unit and the TDD communication system and maintaining communication between the mobile unit and the FDD communication system when the synchronization is complete.

A system for managing mobile unit communication handoffs between a frequency division duplex (FDD) communication system and a time division duplex (TDD) communication system, the system comprising:

• an FDD base station within the FDD communication system for communicating with the mobile unit in frequency division duplex mode, and for generating a pilot search signal corresponding to a transmission range of the FDD communication system;
• a TDD base station within the TDD communication system for communicating with the mobile unit in time division duplex mode, and for generating a pilot search signal corresponding to a transmission range of the TDD communication system;
• a mobile unit which is transmitting information via a current one of the FDD and TDD communication systems while moving towards the other, or targeted one of the FDD and TDD communication systems, the mobile unit comprising:
• a receiving unit to receive the first and second pilot search signals, and to initiate a handoff from the current communication system to the targeted communication system when the pilot search signal from the targeted communication system has reached a predetermined threshold level;
• and
• a dual-transceiver to synchronize concurrent communications between the mobile unit and the current and targeted communication systems, and to concurrently communicate the information with the current communication system and the targeted communication system upon synchronization, wherein the dual-transceiver comprises a burst mode capable of increasing a data rate between the mobile unit and the current and targeted communication systems during the handoff to concurrently support communication with both the current and targeted communications systems.

A method for maintaining a connection between a frequency division duplex (FDD) communication system and a time division duplex (TDD) communication system during handoff of a communication unit from one communication system to the other, the method comprising:

• transmitting a first portion of a communication frame to one of the FDD and TDD communication systems;
• transmitting a second portion of the communication frame to the other one of the FDD and TDD communication systems;
• transmitting at least one of the first and second portions of the communication frame at an increased data rate;
• and
• wherein communication occurs with both the FDD and TDD systems during the transmission of the communication frame, and wherein the communication occurs in a time equivalent to the time required to transmit the communication frame to either of the FDD and TDD systems when no handoff is occurring.

A method for controlling information transmissions between a communications unit and frequency division duplex (FDD) and time division duplex (TDD) communication systems, wherein the communication unit is transmitting information via a first one of the FDD and TDD communication systems, the method comprising:

• generating a cell identification signal corresponding to a transmission range of a second one of the FDD and TDD communication systems;
• initiating substantially simultaneous communication between the communications unit and both the FDD and TDD communications systems when the communications unit acknowledges the cell identification signal and is thereby in the coverage area of both the FDD and TDD communications systems;
• and
• maintaining the substantially simultaneous communication between the communications unit and each of the FDD and TDD communications systems by simultaneously communicating at least a part of the information with each of the FDD and TDD communications systems.

A method for controlling mobile unit communication handoffs between a frequency division duplex (FDD) communication system and a time division duplex (TDD) communication system, the method comprising:

• transmitting between the mobile unit and a current communication system;
• generating a pilot search signal corresponding to a transmission range of a targeted communication system, the current communication system being different from the targeted communication system;
• monitoring pilot search signals at designated frequencies using one of time division processing and frequency division processing;
• initiating a communication handoff from the current communication system to the targeted communication system when the mobile unit recognizes a predetermined threshold level of the pilot search signal;
• transmitting a synchronizing preamble to the targeted communication system in a portion of a frame to synchronize concurrent communications between the mobile unit and both the current and targeted communication systems;
• and
• terminating transmission between the mobile unit and the current communication system and maintaining communication between the mobile unit and the targeted communication system when synchronization is complete.

A method for controlling mobile unit communication handoffs between a frequency division duplex (FDD) communication system and a time division duplex (TDD) communication system, the method comprising:

• transmitting between the mobile unit and the FDD communication system;
• generating a pilot search signal corresponding to a transmission range of the TDD communication system;
• monitoring pilot search signals at designated frequencies using time division processing;
• initiating a communication handoff from the FDD communication system to the TDD communication system when the mobile unit recognizes a predetermined threshold level of the pilot search signal;
• synchronizing concurrent communications between the mobile unit and both the FDD and TDD communication systems;
• and
• terminating transmission between the mobile unit and the FDD communication system and maintaining communication between the mobile unit and the TDD communication system when synchronization is complete.

A method for controlling mobile unit communication handoffs between a time division duplex (TDD) communication system and a frequency division duplex (FDD) communication system, the method comprising:

• transmitting between the mobile unit and the TDD communication system;
• generating a pilot search signal corresponding to a transmission range of the FDD communication system;
• monitoring pilot search signals at designated frequencies using frequency division processing;
• initiating a communication handoff from the TDD communication system to the FDD communication system when the mobile unit recognizes a predetermined threshold level of the pilot search signal;
• synchronizing concurrent communications between the mobile unit and both the FDD and TDD communication systems;
• and
• terminating transmission between the mobile unit and the TDD communication system and maintaining communication between the mobile unit and the FDD communication system when synchronization is complete.