Method and system for initiating bi-directional communication in a time-division duplex communication system

A method at a customer premises equipment (CPE) modem for initiating bi-directional communication in a time-division duplex (TDD) communication system between the CPE modem and an operator modem, the method comprising:

• receiving by the CPE modem noise induced by crosstalk for consecutive discrete time slots in a transmission frequency band,
• identifying at the CPE modem a timing structure of time slots in the transmission frequency band using the noise induced by crosstalk for the consecutive discrete time slots,
• interpreting at the CPE modem a direction of transmission in the time slots based on the timing structure identified using the noise induced by crosstalk,
• aligning transmission of the CPE modem with the time-division duplex timing structure present in the received noise induced by crosstalk, by transmitting initiation signals from the CPE modem to the operator modem in time periods between downstream transmission slots,
• receiving by the CPE modem an initiation response signal transmitted from the operator modem in downstream transmission time slots, and
• after transmitting the initiation signals and after receiving the initiation response, proceeding at the CPE modem with a subsequent initiation procedure to establish bi-directional communication between the CPE modem and the operator modem;
• wherein the timing structure of time slots in the transmission frequency band displays a variation in power with time slots of higher or lower power than average power over the transmission frequency band.

A customer premises equipment (CPE) modem for initiating bi-directional communication in a time-division duplex (TDD) communication system between the CPE modem and an operator modem, the CPE modem comprising:

• a receiver adapted to receive noise induced by crosstalk for consecutive discrete time slots in a transmission frequency band, and
• a processor adapted to identify a timing structure of time slots in the transmission frequency band using the noise induced by crosstalk for the consecutive discrete time slots, to interpret a direction of transmission in the time slots based on the timing structure identified using the noise induced by crosstalk, and to align transmission of the CPE modem with a time-division duplex timing structure present in the received noise, by transmitting initiation signals to the operator modem in time periods between downstream transmission slots,
• the receiver being further adapted to receive an initiation response signal transmitted from the operator modem in downstream transmission time slots, the processor is further adapted to proceed with a subsequent initiation procedure to establish bi-directional communication between the CPE modem and the operator modem after transmitting the initiation signals and after receiving the initiation response;
• wherein the initiation signals comprise handshake tones, and wherein the initiation response signal comprises a handshake response signal.