Signaling for Random Access in Time Division Duplexed (TDD) Systems with Traffic Adaptation

An access point (AP) comprising:

• a processor;
• and
• a computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
• transmit a first signal to a set of user equipments (UEs), the first signal assigning a first set of RACH transmission opportunities in the cell to at least a first sub-set of UEs in the set of UEs;
• and
• transmit a second signal to a second sub-set of UEs in the set of UEs, the second signal assigning a second set of RACH transmission opportunities in the cell to the second sub-set of UEs.

A user equipment (UE) comprising:

• a processor;
• and
• a computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
• receive a system information block (SIB) signal configuring a set of uplink subframes, wherein the SIB signal comprises a first field allocating a sub-set of uplink subframes for RACH transmission by a group of legacy user equipments (UEs);
• and
• receive a second signal reconfiguring at least some uplink subframes in the set of uplink subframes as downlink subframes without reconfiguring any uplink subframes in the sub-set of uplink subframes allocated for RACH transmission by the group of legacy UEs, wherein the second signal is undetected by the group of legacy UEs.

A method for managing random access channel (RACH) transmission opportunities within a cell of a network, the method comprising:

• broadcasting, by a base station, a first index to a group of legacy user equipments (UEs) and a group of next-generation UEs, the first index indicates an initial uplink-downlink configuration in the cell;
• allocating a set of subframes for RACH transmission by the group of legacy UEs, wherein the of subframes are configured for uplink transmission during the initial uplink-downlink configuration;
• selecting an uplink-downlink configuration from a plurality of possible uplink-downlink configurations in accordance with a selection criteria, wherein the selection criteria requires the set of subframes allocated for RACH transmission by the group of legacy UEs to remain configured for uplink transmission for the selected uplink-downlink configuration;
• and
• sending a second index to the group of next-generation UEs, wherein the second index indicates the cell is transitioning from the initial uplink-downlink configuration to the selected uplink-downlink configuration, and wherein the second index is undetected by the group of legacy UEs.