Lucent Technologies Inc.

Chu Ng

Joseph L Ciccone

David C Nall

Sanjay Kasturia

Colin Alan Warwick

John G Israel

Bradley A McKay

Jay E Padgett

William Czarnocha

An arrangement is provided which detects the loss of a high power signal in an optical transmission path and the loss of supervisory signal power and, in response thereto, automatically invokes a procedure which causes an optical signal source connected to the fiber to reduce the power level at which it is transmitting optical signals over the fiber to a safe level. More specifically, reduction of optical signal power supplied by an upstream network element by a prescribed amount is achieved by automatically controlling the output power level of the upstream network element in response to the detection of both loss of signal power and loss of supervisory signal power at a downstream network element as a result of a fiber cut, open connector, or other potentially hazardous discontinuity.

Automatic power shut-down arrangement for optical line systems

A cordless telephone is arranged for operation in a frequency hopping system includes an arrangement which achieves optimum utilization of multiple cordless telephone portable units by permitting these units to simultaneously access a common base unit. A physical layer of an air interface is provided by a two channel time division multiple access protocol for supporting a two channel multiple access system for the portable units. These two channels are considered as virtual channels and not dedicated to any particular telephone line, as in the case of two line telephone products. Nor are these two channels dedicated to any particular portable unit, but rather they are available for use by any portable unit in the telephone. A signaling layer of the air interface is provided for supporting the two channel multiple access system. Two types of subframes, acquisition and traffic, are illustratively provided in the air interface for the cordless telephone. The acquisition subframe is a synchronization frame that is configured for fast and reliable symbol and frame timing recovery. Single frame acquisition even in an extreme user hostile environment is achievable. Traffic subframes are used after a communication link has been built and full voice and/or data is interchanged. Signaling between the base unit and portable units is supported during both the traffic mode and the acquisition mode.

Cordless telephone arranged for operating with multiple portable units

A cordless telephone arranged for operation in a frequency hopping system includes an arrangement which achieves optimum utilization of multiple cordless telephone portable units by permitting these units to not only access a common base unit, but also to access each other. In establishing communications between portable units, a first portable unit in the system, in response to a user-initiated request at this unit, transmits a broadcast or page signal to other portable units, also in the system, using a multiple channel frequency hopping sequence. Once a second portable unit in the system responds, a communication link between the first and second portable units is established. A third portable unit in the system may also respond to the user initiated request and join the communication link existing between the first and second portable units. Such portable-unit-to-portable-unit communication link may be established irrespective of whether a base unit to portable unit communication link then exists in the system. After the communication link with the first, second and possibly third portable unit is established, these portable units move to and use a multiple channel frequency hopping sequence that is different from the frequency hopping sequence used to establish the communication link. In this way, the original hopping sequence remains available for other portable units to build similar communication links. Thus, an unlimited number of portable-unit-to-portable-unit communication links may be built and maintained in the system.

Arrangement for configuring multiple portable units for communicating

A cordless telephone arranged for operation in a frequency hopping system provides for conserving battery power in a portable unit when this unit is located remote from its charging station and in a standby state. While in the standby state, the portable unit resides in a low power monitoring mode which includes deactivating certain internal circuitry and periodically activating and deactivating other selected internal circuitry for conserving battery power. When the portable unit is periodically activated from a deactivated state, battery power is conserved through an adaptive operation that reduces considerably the length of time that the selected internal circuitry needs to remain turned on. This reduced on-time period for the selected internal circuitry is provided as long as the base unit is detected as frequency hopping with at least one other of the portable units in the system. If the base unit is not detected as frequency hopping, however, the length of time that the selected internal circuitry remains on is left at its normal, unreduced on-time period. Energy savings for a portable unit operating with the reduced on-time period are significantly greater than those realized when the portable unit is operated with the normal, unreduced on-time period. Another portable unit operating as the base unit may also provide a frequency hopping signal suitable for use by the adaptive operation in providing the reduced on-time period for the internal circuitry of the portable unit.

Apparatus and method for prolonging battery life in a portable telephone

Communication links are quickly and reliably established between units of a cordless telephone configured for operating in a frequency hopping system. This is achieved through specific processes which detects frequency hopping patterns that are embedded in radio frequency noise. A first process is executed by the base unit and/or each of multiple handset units in the cordless telephone for performing a link acquisition with another unit, also in the cordless telephone. In the execution of this process, multiple profile scans of the frequency hopping channels are executed to build up over time tables with information about energy in all of the channels in the frequency spectrum that are used by the units in the cordless telephone for frequency hopping. In the tables will be spectrum energy from a frequency hopping base unit or handset unit that appears as a recognizable pattern. By applying correlation techniques to the pattern in each table, information is obtained which reflects the probability that a hopping pattern for an associated unit in the cordless telephone has been detected. The unit obtaining this information is then able to quickly join the frequency hopping cycle of the detected base unit or handset unit. An abbreviated second process also is executed by each of multiple handset units in the cordless telephone for performing a link acquisition with another unit, also in the cordless telephone. In the execution of this process, multiple profile scans of the frequency hopping channels are executed to build up over time tables with information about the energy in some minimum number of channels that are used by the units in the frequency spectrum. This process is executed when the searching unit has previous information as to the possible location for the hopping unit in the frequency hopping cycle. In this process, the frequency hopping cycle is easily detected and synchronization with this cycle quickly obtained.

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Woodbridge, NJ, United States of America

Chu Ng