Abstract: In certain types ol transmission system using nQ,1M it may be desirable to use a control applications in muIticarrier snrstems with variable bitloading it is particularly desirible that the control channel data be separable from user data when the value of n. i.e the bitloading. or constellation identifier are unknown. Binary data is transmitted using nQAM modulation. The binary data comprises both user data and cointro,l clata. This means that a control channel is superimposed on a user data channel within the same nQAM constellation. Separation of said control data is lacilitated by arranging control data points to have either unique phase, or unique amplitude, values. These unique values are not employed for user data points.

Abstract: A multi-carrier transmission system such as a DMT based VDSL system. The system uses orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. This estimate includes digital receiver and transmitter units with the receiver unit including a symbol detection unit. This system is adapted to determine a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point. It compares the parameter with an upper lower limit and if the parameter is outside the limits, changes the constellation used to modulate the carrier to a neighboring constellation. The symbol detection unit may be used to determine a parameter such as the ratio d2/&sgr;2, where d is the shortest distance between neighboring constellations, &sgr; is a standard deviation and &sgr;2 is the variance of the deviations of the input and output signal values of the symbol detection unit.

Abstract: A multi-carrier transmission system, for example a DMT system. Channel information is transmitted between two transceivers using a plurality of subcarriers. Each subcarrier, or symbol, has a parameter associated with it. The transceivers are adapted to transmit the channel information as a sequence of n groups in which each of the n groups contains information concerning the number of adjacent subcarriers which have the same value as the parameter, together with the actual value of the parameter. The parameter which may have a plurality of discrete values, may be a bit-loading value, or a QAM constellation identifier.

Abstract: A multi-carrier transmission system, such as a DMT system. A receiver must be able to recover a sampling clock that is very accurately synchronized to a transmitter sampling clock. Typically, synchronization is achieved by using a reserved carrier, the pilot carrier, which is transmitted with a fixed phase. The receiver sampling clock is then phase locked to the pilot carrier. Frame timing can be recovered by using a correlation technique. Thus an improved method of recovering a sample clock and phase locking the sampling clock to a pilot carrier is provided.

Abstract: A two-way multi-carrier transmission system, such as a DMT system. If there are dynamic changes in the transmission parameters, synchronization must be maintained between the transmitter and the receiver when the transmission parameters changed. The first stage of such a process requires that the changes of parameter be notified by one transceiver to others involved in an active communication process over a slow transmission channel such as the control channel. Subsequently, the synchronization transceiver is adjusted simultaneously, i.e., from a predetermined DMT symbol. Such adjustments in time synchronization must be achieved with a minimum of overhead.

Abstract: A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of a plurality of bits per carrier and symbol. The system uses some method for the determination of an inverse channel model to be used in the equalization process. In the frequency domain, this is normally based on an estimate of the channel attenuation and phase for each carrier. A simplified method of equalization is provided which uses data at the symbol carrier input and output to adaptively estimate an inverse channel model.

Abstract: A multi-carrier transmission system using DMT. It is known to recover a receiver sample and clock from a reserved carrier, a pilot carrier having a fixed phase. A sampling clock oscillator in a receiver is then phase locked to the pilot carrier. Multi-carrier receivers, such as DMT receivers, are normally equipped with an FFT processor. A complex number representing the pilot carrier is then available from the FFT processor output. If an FFT processor is not available, a one frequency DFT processor can be provided to produce a complex estimate of the pilot carrier. In a DMT system, frame synchronization is handled separately from sampling clock synchronization, although the two processes are intimately related and frame synchronization must be acquired before sampling clock synchronization.

Abstract: A multi-carrier transmission system, particularly a discrete multi-tone (DMT) system. Data is transmitted between two transceivers using a plurality of carriers. The frequency bandwidth of the system is divided between the plurality of carriers. The transmission system is adapted for operation in a heterogeneous network including a number of subscriber equipments having different channel characteristics and coexisting on the same cable. The length of cable for each subscriber terminal varies in relation to its respective location. The transmission system includes an allocation device for allocating the traffic of subscriber equipments having a shorter length of cable to tones starting from a higher frequency band of the system bandwidth.

Abstract: A window including a window frame and a casement, the latter being mounted in the frame with the aid of a link-arm mechanism. The casement is pivotable from a closed position within the frame, through 180.degree. to a closed, fully reversed position in the frame. From the latter position, it is pivotable further in the same direction or reversely in the opposite direction.