Coexisting communication systems

A communication system comprising:

• a first base station unit, said first base station unit operating according to a first protocol for time division multiple access communication in a first cellular region;
• a second base station unit, said second base unit operating according to a second protocol for time division multiple access communication in a second cellular region at least partially overlapping with said first cellular region;
• and
• a synchronization signal connected from said first base station unit to said second base station unit, whereby first communications between said first base station unit and user stations using said first protocol are coordinated with second communications between said second base station unit and user stations using said second protocol so as to prevent collisions between said first communications and said second communications.

A method for communication comprising the steps of:

• defining a plurality of first time frames, each comprising a first group of time slots,
• defining a plurality of second time frames, each comprising a second group of time slots, wherein said first group of time slots and said second group of time slots overlap temporally;
• and
• selectively communicating at a given time over only one time slot from said first group of time slots and said second group of time slots.

A communication system comprising

• a first base station unit operating according to a first protocol, whereby communication between a first plurality of user stations and said first base station unit is carried out in time slots and using frequency division duplexing, said first base station unit transmitting over a first frequency band and receiving over a second frequency band;
• a second base station unit operating according to a second protocol, whereby communication between a second plurality of user stations and said second base station unit is carried out using time division duplexing, said first base station unit transmitting and receiving over at least one of said first frequency band and said second frequency band;
• and
• a synchronizing signal between said first base station unit and said second base station unit.

A method for communicating comprising the steps of:

• transmitting, over a first frequency band, a first base-to-user message from a first base station unit to a first user station;
• receiving said first base-to-user message at said first user station;
• transmitting, over a second frequency band at least partially overlapping said first frequency band, a first user-to-base message from a second user station to a second base station unit, said first base station unit and second base station unit being located within a same cell;
• receiving said first user-to-base message at said second base station unit;
• transmitting, over said second frequency band, a second base-to-user message from said second base station unit to said second user station;
• receiving said second base-to-user message at said second user station;
• transmitting, over a third frequency band separate and distinct from said first frequency band, a second user-to-base message from said first user station to said first base station unit;
• and
• receiving said second user-to-base message at said first base station unit.

In a communication system, a timing structure for communication comprising:

• a composite time frame having a duration of 18.46 milliseconds;
• a plurality of first time slots in said composite time frame, each of said first time slots supporting a half-duplex GSM communication link, with a corresponding second half-duplex GSM communication link located on a different frequency band;
• and
• a plurality of second time slots in said composite time frame, each of said second time slots having twice the duration of one of said first time slots, and each of said second time slots supporting two half-duplex time division communication links.