Abstract: The invention relates to a method for converting a digital signal an analogue signal and to a digital to analogue converter comprising means for converting a digital signal to a thermometer coded signal, means for randomizing the thermometer coded signal, means for controlling the means for randomizing based on the digital signal and means for converting the randomized signal to analogue.

Abstract: A method for determining the number of packets lost in a communications network. Marker packets are inserted before and after a predetermined number of packets in a data stream. The number of packets between the inserted marker packets are counted at two different points in the network. Each number of packets counted between the inserted marker packets at the two different points in the network are compared with one another to ascertain the number of packets lost between the two different points in the network.

Abstract: A mobile communications system employs extended channel assignment messaging during the call setup portion of a mobile call. As part of the call setup process, a mobile station sends an access request message to a primary base station that includes a list of alternate base stations. As call setup continues, the mobile station employs diversity reception in monitoring the paging channel of three base stations, each selected as a function of the strength of the signal-to-noise ratios of their respective pilot tones.

Abstract: An ATM network element receives a stream of data associated with a particular user. This data stream is further partitioned into frames and ATM cells. A predefined traffic set is associated with the user. The ATM network element evaluates the received data stream for conformance to the user's traffic set at every frame boundary. If a particular frame is conforming, the ATM network element provides a predefined quality of service (QoS) to the user. If a particular frame is non-conforming (and hence there is no commitment to the user of the corresponding QoS), the next (future) frame is evaluated only on the basis of the traffic characteristics of past conforming frames and the future frame. That is, past non-conforming user generated traffic is not used to determine any QoS commitments to future user generated traffic.

Abstract: A virtual dial-up service is provided via multiple Internet Service Provides (ISPs). In particular, a remote user accesses the virtual dial-up service by establishing a connection to a serving ISP. The Serving ISP establishes a first tunnel to an anchor ISP. The latter establishes a tunnel to, e.g., a private intranet. As a result, a virtual private network (VPN) service is provided that enables remote access, via multiple tunnels, to a private network.

Abstract: In a cellular system based on industry standard IS-95 CDMA (code division multiple access), a symbol error count based reverse link outer loop power control technique uses adaptive SER targets. In particular, a base station uses a 2nd order statistic, e.g., standard deviation (variance), to identify, or act as a signature of, a particular cellular (wireless) communications environment. The base station monitors the standard deviation of the symbol error count of a received signal (transmitted from a mobile station). The target signal-to-noise ratio (EbT/N0T) of this received signal is adjusted as a function of the value of the standard deviation and the adjusted EbT/N0T target is used to provide power control.

Abstract: In a wireless data network, such as a General Packet Radio Service (GPRS) network, a transmitter uses one of k coding/modulation schemes for transmitting data. The transmitter initially selects a coding/modulation scheme, C, as a function of carrier-to-interference ratio (C/I) measurements. The transmitter then calculates the number of blocks, B, required to transmit a number of data packets, D, using the coding/modulation scheme C. In addition, the transmitter calculates the number of blocks required to transmit the number of data packets, D, for each coding/modulation scheme that is stronger than the selected coding/modulation scheme C. The transmitter finally selects that coding/modulation scheme that results in transmitting the number of data packets D in B blocks using the strongest coding/modulation scheme. As a result, each block is transmitted using the strongest coding/modulation scheme available.

Abstract: A receiver, comprising an adaptive filter, performs blind equalization using a joint constant modulus algorithm—multimodulus algorithm (CMA-MMA) blind equalization algorithm. The adaptive filter is a two-filter structure. The receiver performs CMA-MMA blind equalization using asymmetric algorithms. This joint CMA-MMA blind equalization technique reduces the rate of occurrence of a diagonal solution.

Abstract: In a packet voice system, a dynamic build-out delay approach in a receiver during the duration of a call. In particular, the build-out delay is applied at least twice during the duration of the call. In one embodiment, a packet voice system includes an ATM Adaptation Layer Type 2 (AAL-2) and Service Specific Convergence Sublayer (SSCS) System. The receiver portion of the SSCS System recovers AAL-2 packets and plays back the compressed audio to a voice decoding element. In providing playback, the receiver applies the build-out delay at the start of each talk-spurt. The voice decoding element provides an uncompressed audio stream. In another embodiment, the receiver portion of the SSCS System applies the build-out delay at the start of the each talk-spurt as a function of the length of the previous silence interval.

Abstract: An ATM network element receives a stream of data associated with a particular user. This data stream is further partitioned into frames and ATM cells. A predefined traffic set is associated with the user. The ATM network element evaluates the received data stream for conformance to the user's traffic set at every frame boundary. The Payload Type Indicator (PTI) of an ATM cell header is used to indicate whether that cell belongs to a non-conforming frame or a conforming frame. In particular, if a frame is determined to be non-conforming, the ATM network element sets the PTI field of at least the end-of-frame cell (i.e., the cell with the UUI bit set to one in AAL5), to a predefined code representative of non-conforming (hereafter referred to as an NCF code). As a result, downstream network elements are able to determine which of the currently buffered cells belong to a non-conforming frame by looking at both the PTI field and the frame boundary marker (UUI bit).

Abstract: A dual-mode receiver uses a hybrid cost function that provides for automatic constellation phase recovery regardless of whether a CAP signal or a QAM signal has been transmitted. In one embodiment, the receiver uses a hybrid cost function that is the superposition of a QAM-based cost function and a CAP-based cost function. In another embodiment, the receiver comprises an adaptive filter that alternates between a QAM-based cost function and a CAP-based cost function. In addition, a method is described that uses information about (a) the expected constellations, and (b) the values before and after a rotator of the receiver for deciding what type of signal is being received.

Abstract: A distributed processing telephone system for providing “plug-and-play” capability. In particular, a key telephone system comprises a plurality of telephone sets. Each telephone set is coupled to at least one common communications channel, or telephone line, and includes at least one tunable RF modem. There is no key service unit (KSU). That is, the system is KSU-less. Resources of the telephone system are allocated using a peer-to-peer protocol. For example, as each telephone set is newly added to the system, the new telephone set adaptively determines its own allocation of resources, e.g., intercom numbers, etc. During operation, each telephone set requests the appropriate resources from its peers.

Abstract: A receiver has a dual mode of operation—a carrierless amplitude modulation/phase modulation (CAP) mode and a quadrature amplitude modulation (QAM) mode-yet only requires a single equalizer structure for both the CAP mode of operation and the QAM mode of operation during blind start-up. The receiver uses the same blind equalization updating algorithm independent of the type of received signal for converging the equalizer structure. The blind equalization updating algorithm incorporates a constant R, whose value is a function of the type of received signal, e.g., a QAM signal or a CAP signal. The type of received signal is determined as a function of the in-phase component of the mean-squared error, E[e2n.

Abstract: A cable modem supports two-way packet-switched traffic and is capable of telephony-type signaling to provide local telephone services over a two-way HFC cable network. The telephony-type signaling is transmitted using the TCP/IP protocol over an HFC distribution plant. This telephony-type signaling includes representations of “off-hook,” “on-hook,” etc. At the customer's premises, the telephony cable modem takes any one of a number of forms. For example, the telephony cable modem comprises terminal equipment ports for coupling to both data terminal equipment such as a personal computer and voice terminal equipment such as a POTS telephone. Alternatively, the telephony cable modem includes POTS functionality and comprises a handset and keypad for dialing. As yet another example, the telephony cable modem includes a terminal equipment port for coupling to data terminal equipment that also functions as a telephone, such as a personal computer equipped with a microphone and speakers.

Abstract: In a packet voice system, discarding of a packet is performed as a function of previously discarded packets. In one embodiment, a packet voice system includes an ATM Adaptation Layer Type 2 (AAL2) and Service Specific Convergence Sublayer (SSCS) System. In this system, a transmission buffer stores AAL2 voice packets for transmission, each AAL2 voice packet comprising a sequence number, the values of which range from 0 to n−1, and a source identifier, k. When traffic congestion is detected, the transmitter portion of the SSCS System selectively discards one packet from a source k at the output of the transmission buffer if no packet from source k was dropped in either the last n−1 packets or over a predefined prior interval of time. Another embodiment of the invention discards packets at the input of the transmission buffer.

Abstract: In a cellular system based on industry standard IS-95 CDMA (code division multiple access), a symbol error count based reverse link outer loop power control technique uses non-adaptive SER targets. In particular, a base station set a fixed target for a 2nd order statistic, e.g., standard deviation (variance), of the symbol error count as a function of a target frame error rate (FER). The base station monitors a symbol error count of a received signal (transmitted from a mobile station). This symbol error count is used to update an estimate of the standard deviation of the symbol error count. This estimate of the standard deviation of the symbol error count is compared with a target standard deviation of the symbol error count to make changes in the EbT/N0T target. The adjusted EbT/N0T target is used to provide power control.

Abstract: An alternate access platform is coupled to the Internet, a local-exchange-carrier (LEC), and other communications facilities such as a plurality of long-distance facilities provided by any one of a number of long distance carriers. Access to the alternate access platform occurs in any one of a number of ways. For example, a user, or calling party, establishes an Internet connection to the alternate access platform, or dials into the alternate access platform via a local plain-old-telephone-service (POTS) call. Independent of the access method, the alternate access platform selects a communications facility for routing the call as a function of a “call profile” associated with the calling party. This “call profile” uses any one of a number of parameters to determine routing such as called party, cost, quality, reliability, time-of-day, etc. This “call profile” is either determined by the user on a call-by-call basis, or is separately administered by the user.

Abstract: An AAL2/SSCS packet voice system multiplexes various forms of voice-band traffic including voice packets, fax packets, and data packets into a virtual circuit (VC). This AAL2/SSCS packet voice system executes a dynamic call admission algorithm that takes into account call type in deciding whether to admit a new call to the VC. In particular, this approach takes into account different bandwidth needs for different call types. The AAL2/SSCS packet voice system also performs bit or block dropping on voice packets to mitigate the effects of traffic congestion. The bit or block dropping is done based on the packet queue fill value exceeding at least one queue threshold. Further, the AAL2/SSCS packet voice system also dynamically varies a queue threshold as a function of capacity.