A multi-zone analog-to-digital converter (ADC) is provided that includes a track-and-hold (T/H) stage having a bandwidth of L Hertz (Hz) to accept an analog input signal, a clock input to accept a clock signal with a clock frequency of P Hz, and N deinterleaved signal outputs with a combined bandwidth of M Hz. N(P/2)=M, L>QM, and Q is an integer >1. The T/H stage is able to sample an analog input signal in the Qth Nyquist Zone, where Q is an integer. A quantizer stage has N interleaved signal inputs connected to corresponding T/H stage signal outputs, a clock input to accept the clock signal, and an output to supply a digital output signal having a bandwidth of M Hz. A packaging interface typically connects the T/H stage to the quantizer stage, and has a bandwidth less than the clock frequency.

Systems and methods providing for dynamic switching between the various waveforms on the downlink are described. Embodiments of a dynamic downlink waveform switching implementation may, for example, support utilization of one or more multiple carrier (MC) waveform (e.g., OFDMA) or other high peak to average power ratio (PAPR) waveform and one or more SC (SC) waveform (e.g., discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM)) or other low PAPR waveform. Dynamic selection of a downlink waveform may be made by an access point based upon various metrics, including relative distance to a served an access terminal and the preference of downlink waveform indicated by a served an access terminal. A downlink waveform selection indication may be signaled from the access point to the served an access terminal using downlink control information (DCI).

Systems and methods for applying a pilot tone to multiple spectral bands are provided. An initial signal is divided into multiple spectral bands. A pilot tone is applied to each of the spectral bands, and then the signals are again combined for transmission. The pilot tones differ in some way, for example in phase or frequency.

A transmission system for performing communication according to time division duplex (TDD), includes a relay unit configured to relay uplink signals and downlink signals in the first and second communication systems, a TDD information estimation unit configured to estimate a transmission stop period during which no uplink signal of the first communication system is transmitted, an estimation error detection unit configured to detect that the estimation of the transmission stop period is erroneous on the basis of the uplink signal or the downlink signal of the first communication system, and a bandwidth allocation unit configured to prioritize allocation of a bandwidth in the relay unit for the uplink signal of the first communication system over allocation of a bandwidth in the relay unit for the uplink signal of the second communication system if the estimation of the transmission stop period is erroneous.

An apparatus comprises an uncooled laser; a splitter coupled to the laser; a first wavelength component coupled to the splitter; a local oscillator (LO) port coupled to the first wavelength component; a modulator coupled to the splitter; a second wavelength component coupled to the modulator; and a signal port coupled to the second wavelength component. A method comprises emitting an input light; splitting the input light into a first local oscillator (LO) optical signal and a first unmodulated optical signal; modulating the first unmodulated optical signal using polarization-multiplexed, high-order modulation to produce a first modulated optical signal; transmitting the first LO optical signal to a first duplex fiber; and transmitting the first modulated optical signal to a second duplex fiber.

Apparatus and methods are provided for application layer optimization in a modern data network. The optimization incorporates variable rate transmission across one or more optical data channels. Data throughput is maximized by enabling quality of service profiles on a per transmission channel basis. According to one aspect, a system is provided in which the application layer is aware of and controls the underlying transmission rate and quality of the transmission. This enables the system to fully utilize the transmission capacity of the channel. The application layer may map different applications to different transmission classes of service. The services can be classified based on data throughput rate, guaranteed error rates, latency and cost, among other criteria. This provides flexibility to the application layer to map some loss tolerant applications to a lower cost (per bit) transmission class.

A method for generating a tone signal (TS) having a tone frequency, f, wherein the method comprises the following steps: supplying (S1) a binary bit stream (BBS) having a mark pattern with a supply bit rate, BR, to a signal filter unit; and filtering (S2) the supplied binary bit stream (BBS) by said signal filter unit to generate the tone signal (TS), wherein the mark pattern of the binary bit stream (BBS) supplied to said signal filter unit is adapted to minimize a ratio of the supply bit rate, BR, to the tone frequency, f, of the generated tone signal (TS).

Systems and methods for performing wavelength conflict detection are provided. These are to detect situations in optical networks where two instances of the same wavelength channel have been added. Wavelength conflict detection is performed for each of a plurality of possible wavelength channels that could be present in an optical signal, each wavelength channel that is present modulated by a pilot tone signal with a respective pilot tone frequency, the pilot tone signal carrying M-ary pilot tone data, M=2.sup.n, n?1, with a respective one of M different sequences being used to represent each of M possible data values over a data value period. Conflict detection for each wavelength channel involves performing correlation peak detection using each of the M different sequences to determine correlation peaks for each of the M different sequences, and, based on the determined correlation peaks, determining whether multiple instances of the wavelength channel are present in the optical signal.

A multi-zone analog-to-digital converter (ADC) is provided that includes a track-and-hold (T/H) stage having a bandwidth of L Hertz (Hz) to accept an analog input signal, a clock input to accept a clock signal with a clock frequency of P Hz, and N deinterleaved signal outputs with a combined bandwidth of M Hz. N(P/2)=M, L>QM, and Q is an integer >1. The T/H stage is able to sample an analog input signal in the Qth Nyquist Zone, where Q is an integer. A quantizer stage has N interleaved signal inputs connected to corresponding T/H stage signal outputs, a clock input to accept the clock signal, and an output to supply a digital output signal having a bandwidth of M Hz. A packaging interface typically connects the T/H stage to the quantizer stage, and has a bandwidth less than the clock frequency.

We disclose embodiments of a WDM transmitter having an in-band OTDR capability for at least a subset of the WDM channels thereof. In an example embodiment, an OTDR-enabled WDM channel of the WDM transmitter is implemented using an optical transceiver that comprises an optical transmitter and a coherent optical receiver. The optical transmitter is configured to generate a modulated optical signal by modulating a respective carrier wavelength, transmit the modulated optical signal through an optical link as a component of the corresponding WDM signal, and provide the respective carrier wavelength to the coherent optical receiver for being used therein as an optical local oscillator. The optical receiver is configured to estimate an impulse response of the optical link by coherently detecting and processing a return optical signal produced within the optical link due to distributed reflection and/or backscattering of the modulated optical signal.