Showing papers on "Time-division multiplexing published in 2014"

Generalized Frequency Division Multiplexing for 5th Generation Cellular Networks

Abstract: Cellular systems of the fourth generation (4G) have been optimized to provide high data rates and reliable coverage to mobile users. Cellular systems of the next generation will face more diverse application requirements: the demand for higher data rates exceeds 4G capabilities; battery-driven communication sensors need ultra-low power consumption; and control applications require very short response times. We envision a unified physical layer waveform, referred to as generalized frequency division multiplexing (GFDM), to address these requirements. In this paper, we analyze the main characteristics of the proposed waveform and highlight relevant features. After introducing the principles of GFDM, this paper contributes to the following areas: 1) the means for engineering the waveform's spectral properties; 2) analytical analysis of symbol error performance over different channel models; 3) concepts for MIMO-GFDM to achieve diversity; 4) preamble-based synchronization that preserves the excellent spectral properties of the waveform; 5) bit error rate performance for channel coded GFDM transmission using iterative receivers; 6) relevant application scenarios and suitable GFDM parameterizations; and 7) GFDM proof-of-concept and implementation aspects of the prototype using hardware platforms available today. In summary, the flexible nature of GFDM makes this waveform a suitable candidate for future 5G networks.

A novel DBA scheme for TDM-PON based mobile fronthaul

Abstract: We propose a mobile-DBA with low-latency for a TDM-PON based mobile fronthaul. It utilizes mobile-scheduling information and reduces the latency to about 1/20 of conventional one. Measured latencies (< 50 µs) are enough for LTE.

FiWi access networks based on next-generation PON and gigabit-class WLAN technologies: a capacity and delay analysis

Abstract: Current Gigabit-class passive optical networks (PONs) evolve into next-generation PONs, whereby high-speed Gb/s time division multiplexing (TDM) and long-reach wavelength-broadcasting/routing wavelength division multiplexing (WDM) PONs are promising near-term candidates. On the other hand, next-generation wireless local area networks (WLANs) based on frame aggregation techniques will leverage physical-layer enhancements, giving rise to Gigabit-class very high throughput (VHT) WLANs. In this paper, we develop an analytical framework for evaluating the capacity and delay performance of a wide range of routing algorithms in converged fiber-wireless (FiWi) broadband access networks based on different next-generation PONs and a Gigabit-class multiradio multichannel WLAN-mesh front end. Our framework is very flexible and incorporates arbitrary frame size distributions, traffic matrices, optical/wireless propagation delays, data rates, and fiber faults. We verify the accuracy of our probabilistic analysis by means of simulation for the wireless and wireless-optical-wireless operation modes of various FiWi network architectures under peer-to-peer, upstream, uniform, and nonuniform traffic scenarios. The results indicate that our proposed optimized FiWi routing algorithm (OFRA) outperforms minimum (wireless) hop and delay routing in terms of throughput for balanced and unbalanced traffic loads, at the expense of a slightly increased mean delay at small to medium traffic loads.

Software defined networking (SDN) over space division multiplexing (SDM) optical networks: features, benefits and experimental demonstration

Abstract: We present results from the first demonstration of a fully integrated SDN-controlled bandwidth-flexible and programmable SDM optical network utilizing sliceable self-homodyne spatial superchannels to support dynamic bandwidth and QoT provisioning, infrastructure slicing and isolation. Results show that SDN is a suitable control plane solution for the high-capacity flexible SDM network. It is able to provision end-to-end bandwidth and QoT requests according to user requirements, considering the unique characteristics of the underlying SDM infrastructure.

On-chip multiplexing conversion between wavelength division multiplexing-polarization division multiplexing and wavelength division multiplexing-mode division multiplexing.

Abstract: A compact silicon-on-insulator device used for conversions between polarization division multiplexing (PDM) and mode division multiplexing (MDM) signals is proposed and experimentally demonstrated by utilizing a structure combining the improved two-dimensional grating coupler and two-mode multiplexer. The detailed design of the proposed device is presented and the results show the extinction ratio of 16 and 20 dB for X- and Y-pol input, respectively. The processing of 40 Gb/s signal is achieved within the C-band with good performance. The proposed converter is capable of handling multiple wavelengths in wavelength division multiplexing (WDM) networks, enabling the conversions between WDM-PDM and WDM-MDM, which is promising to further increase the throughput at the network interface.

Towards 100 channel dense wavelength division multiplexing with 100GHz spacing on silicon

Abstract: A 1 by 4 wavelength division multiplexer with 0.5nm bandwidth and no free spectral range limitation is demonstrated on silicon. The device utilizes wide bandwidth filters cascaded with ring resonators in order to select specific ring resonator modes and route each resonant mode to a separate port. This technology will enable dense wavelength division multiplexing covering the C - and L - bands with up to 100 10GB/s channels separated by 100GHz to be implemented for optical interconnects applications. A 1 by 4 wavelength division multiplexer with 3dB channel bandwidths as small as 0.5nm and 1dB insertion loss are demonstrated with 16dB inter-channel crosstalk suppression. A second wavelength division multiplexer scheme with four channels, each spaced 0.5nm apart without any free spectral range limitations is also demonstrated using wide bandwidth filters centered at the same wavelength to select resonances from four different ring resonators with slightly different widths.

2 x 20 Gbps - 40 GHz OFDM Ro-FSO transmission with mode division multiplexing

Abstract: Radio-over-Free-Space-Optics (Ro-FSO) is a promising technology for future wireless networks. In this work, we have designed a hybrid orthogonal frequency division multiplexing (OFDM) Ro-FSO system for transmission of two independent channels by mode division multiplexing. Two independent 40 GHz radio signals are optically modulated at 20Gbps by mode division multiplexing of two laser modes LG00 and LG10 and transmitted over a free-space link of 20 km to 100 km. The performance of proposed Ro-FSO system is also evaluated under the effect of strong atmospheric turbulences.

320 Gb/s Nyquist OTDM received by polarization-insensitive time-domain OFT

Abstract: We have demonstrated the generation of a 320 Gb/s Nyquist-OTDM signal by rectangular filtering on an RZ-OTDM signal with the filter bandwidth (320 GHz) equal to the baud rate (320 Gbaud) and the reception of such a Nyquist-OTDM signal using polarization-insensitive time-domain optical Fourier transformation (TD-OFT) followed by passive filtering. After the time-to-frequency mapping in the TD-OFT, the Nyquist-OTDM signal with its characteristic sinc-shaped time-domain trace is converted into an orthogonal frequency division multiplexing (OFDM) signal with sinc-shaped spectra for each subcarrier. The subcarrier frequency spacing of the converted OFDM signal is designed to be larger than the transform-limited case, here 10 times greater than the symbol rate of each subcarrier. Therefore, only passive filtering is needed to extract the subcarriers of the converted OFDM signal. In addition, a polarization diversity scheme is used in the four-wave mixing (FWM) based TD-OFT, and less than 0.5 dB polarization sensitivity is demonstrated in the OTDM receiver.

Channel capacity distribution of Layer-Division-Multiplexing system for next generation digital broadcasting transmission

Abstract: Cloud transmission (Cloud-Txn) with Layer-Division-Multiplexing (LDM) was proposed as a candidate Physical Layer (PHY) technology for next generation digital TV broadcasting system This paper presents a fundamental analysis on the channel capacity allocation among the different layers of a LDM-based transmission system The analysis reveals that, for delivering fixed and mobile TV services in the same RF channel, by controlling the power allocation among the layers, the LDM-based system provides much better efficient usage of the spectrum as compared to the single-layer Time-Division-Multiplexing (TDM) or Frequency-Division-Multiplexing (FDM)-based systems The spectrum efficiency of LDM allows the simultaneous delivery of a high-data-rate UHDTV service and a mobile HDTV service within a single 6 MHz channel

Scalable Video Broadcasting Using Bit Division Multiplexing

Abstract: Scalable extension to the H.264/AVC video compression standard (SVC) enables one or more subset bit streams (layers) with multiple qualities to be contained in one high-quality video bit stream, which is a good solution for simultaneous transmission of video programs with different qualities. To fulfill the target of scalable video broadcasting (SVB), the transmission of SVC in broadcasting system uses the physical layer sub-channel technique, and different layers are transmitted in different sub-channels. Bit division multiplexing (BDM) is a newly proposed physical layer sub-channel technique at bit level, which could achieve higher transmission efficiency than conventional time division multiplexing scheme and improve the flexibility of the broadcasting system in conventional hierarchical modulation. In this paper, the combination of SVC and BDM technique is proposed and implemented for SVB. In addition, simplified BDM scheme, BDM-Lite, is also investigated for SVB, which significantly decreases the demapping complexity of the baseline layer due to high-order modulation, which is highly desirable for mobile/handheld receivers. Both simulation and FPGA implementation results show that the proposed BDM-Lite scheme has the advantages of both high transmission efficiency and low complexity of baseline reception.

Fast Synchronization 3R Burst-Mode Receivers for Passive Optical Networks

Abstract: This paper gives a tutorial overview on high speed burst-mode receiver (BM-RX) requirements, specific for time division multiplexing passive optical networks, and design issues of such BM-RXs as well as their advanced design techniques. It focuses on how to design BM-RXs with short burst overhead for fast synchronization. We present design principles and circuit architectures of various types of burst-mode transimpedance amplifiers, burst-mode limiting amplifiers and burst-mode clock and data recovery circuits. The recent development of 10 Gb/s BM-RXs is highlighted also including dual-rate operation for coexistence with deployed PONs and on-chip auto reset generation to eliminate external timing-critical control signals provided by a PON medium access control. Finally sub-system integration and state-of-the-art system performance for 10 Gb/s PONs are reviewed.

Multiuser CSK scheme for indoor visible light communications.

Abstract: Color Shift Keying (CSK) is a new modulation scheme for visible light communication systems using RGB LEDs which has been standardized in the PHY III level of the IEEE 802.15.7. This paper proposes some modifications so as to include multiuser capabilities provided by a time-based multiplexing, with the modulation constellation symbols being adapted to encode data with the luminux powers of the red, green and blue color bands respectively. This is achieved by employing a simple and low-complexity time-based pulse signals structure to separate the users’ data symbols, while a three-dimensional signal constellation design is merged to improve data throughput. Numerical simulations are carried out to assess the performance of this novel architecture. The statistical properties of the transmitted RGB signals ensure dimming capabilities and that the illumination function is unaffected by flickering.

Energy-efficiency improvements for optical access

Abstract: This article discusses novel approaches to improve energy efficiency of different optical access technologies, including time division multiplexing passive optical network (TDM-PON), time and wavelength division multiplexing PON (TWDM-PON), point-to-point (PTP) access network, wavelength division multiplexing PON (WDM-PON), and orthogonal frequency division multiple access PON (OFDMA-PON). These approaches include cyclic sleep mode, energy-efficient bit interleaving protocol, power reduction at component level, or frequency band selection. Depending on the target optical access technology, one or a combination of different approaches can be applied.

Space-Time Coding for Generalized Frequency Division Multiplexing

Abstract: Generalized Frequency Division Multiplexing (GFDM) is a novel filtered multicarrier transmission scheme that provides the flexibility required by 5G applications. Its robustness against fading multipath environments can be increased by space-time coding (STC) at the transmitter when the receiver complexity should be kept minimal. In this paper we investigate the application of the Alamouti-STC in GFDM with a maximum ratio combining (MRC) receiver. We show the application to be straight-forward in contrast to the difficulties that arise in FBMC/OQAM due to its OQAM-modulation. The performance is evaluated by comparing coded GFDM and OFDM transmissions in frequency-selective fading channels.

High precision FPGA implementation of neural network activation functions

Abstract: The efficient implementation of artificial neural networks in FPGA boards requires tackling several issues that strongly affect the final result. One of these issues is the computation of the neuron's activation function. In this work, a detailed analysis of the FPGA implementations of the Sigmoid and Exponential functions is carried out, in a approach combining a lookup table with a linear interpolation procedure. Further, to optimize board resources utilization, a time division multiplexing of the multiplier attached to the neurons was used. The results are evaluated in terms of the absolute and relative errors obtained and also through measuring a quality factor and the resource utilization, showing a clear improvement in relationship to previously published works.

Experimental demonstration of real-time adaptively modulated DDO-OFDM systems with a high spectral efficiency up to 5.76bit/s/Hz transmission over SMF links.

Abstract: In this paper, a FPGAs-based real-time adaptively modulated 256/64/16QAM-encoded base-band OFDM transceiver with a high spectral efficiency up to 5.76bit/s/Hz is successfully developed, and experimentally demonstrated in a simple intensity-modulated direct-detection optical communication system. Experimental results show that it is feasible to transmit a raw signal bit rate of 7.19Gbps adaptively modulated real-time optical OFDM signal over 20km and 50km single mode fibers (SMFs). The performance comparison between real-time and off-line digital signal processing is performed, and the results show that there is a negligible power penalty. In addition, to obtain the best transmission performance, direct-current (DC) bias voltage for MZM and launch power into optical fiber links are explored in the real-time optical OFDM systems.

New Trends of Transmission Capacity Evaluation of Submarine Fiber Cable systems with Different Ultra-High Multiplexing, Amplification and Propagation Techniques

Abstract: This paper has presented the new trends of the performance evaluation of submarine fiber cable system with different ultra-high multiplexing and propagation techniques over a wide range of the affecting parameters. We have taken into account the ultimate optical transmission of 10,000 channels huge submarine cables under different depth conditions. Two amplification techniques are considered (the engagement of Raman and Erbium-doped fiber amplifiers). The double impact of both temperature and pressure is investigated through the defined depth penalty. Three transmission time division multiplexing techniques are studied, namely soliton, nonlinear and maximum time division multiplexing. Also, two multiplexing methods are considered in the design of ultra-wide wavelength division multiplexing (UW-WDM) (10,000 optical channels) and ultra-wide space division multiplexing UW-SDM (400 fiber links). Based on experimental data, both the deep ocean water temperature and pressure are tailored as functions of the water depth. The product of the transmitted bit rate and the repeater spacing is processed over wide ranges of the affecting parameters, where both the repeater spacing and the transmitted soliton bit rate are in positive correlations with the total number of links.

Dynamic vision sensor with shared pixels and time division multiplexing for higher spatial resolution and better linear separable data

Abstract: A Dynamic Vision Sensor (DVS) where pixel pitch is reduced to increase spatial resolution. The DVS includes shared pixels that employ Time Division Multiplexing (TDM) for higher spatial resolution and better linear separation of pixel data. The pixel array in the DVS may consist of multiple N×N pixel clusters. The N×N pixels in each cluster share the same differentiator and the same comparator using TDM. The pixel pitch is reduced (and, hence, the spatial resolution is improved) by implementing multiple adjacent photodiodes/photoreceptors that share the same differentiator and comparator units using TDM. In the DVS, only one quarter of the whole pixel array may be in use at the same time. A global reset may be done periodically to switch from one quarter of pixels to the other for detection. Because of higher spatial resolution, applications such as gesture recognition or user recognition based on DVS output entail improved performance.

Interference classification-based carrier sense adaptive transmission (csat) in unlicensed spectrum

Abstract: Systems and methods for Carrier Sense Adaptive Transmission (CSAT) for reducing interference between Radio Access Technologies (RATs) in unlicensed spectrum are disclosed. A small cell base station may receive signals via a resource, wherein a first RAT is used to receive the signals, and classify interference on the resource associated with the first RAT based on the received signals. Based on the interference classification, one or more cycling parameters may be set for a Time Division Multiplexing (TDM) communication pattern defining activated and deactivated periods of transmission for a second RAT sharing the resource, and operation of the second RAT may be cycled between activated and deactivated periods of transmission over the resource in accordance with the TDM communication pattern.

Ultrahigh-capacity access network architecture for mobile data backhaul using integrated W-band wireless and free-space optical links with OAM multiplexing

Abstract: In this Letter, we propose and experimentally demonstrate a novel access network architecture using hybrid integrated W-band wireless and free-space optical (FSO) links with orbital angular momentum (OAM) multiplexing. The transmission of a 20 GBd quadrature phase-shift keying signal modulated over 10 OAM modes has been demonstrated over a 0.6 m FSO link and a 0.4 m W-band wireless link at 100 GHz. The experimental results show that the architecture can support future ultrahigh-capacity, converged optical–wireless access networks that require extra bandwidth and system flexibility in mobile data networks.

OFDM/WDM PON with laserless, colorless 1 Gb/s ONUs based on Si-PIC and slow IC

Abstract: We introduce a next-generation long-reach access optical network (35 dB loss budget +2 dB margin) delivering up to 40G/40G per passive 1:256 optical distribution network, supporting symmetrical 1 Gb/s rates per home user or up to 40 Gb/s for business users (e.g., enterprises, antenna sites). The proposed system is based on a novel spectrally efficient orthogonal frequency division multiplexing/wavelength division multiplexing OFDM/WDM architecture symmetrically using 16-QAM OFDM polarization diversity in both the downstream and upstream in order to serve low-cost energy-efficient symmetric 1 Gb/s optical network units (ONUs), which are self-coherent, laserless, colorless, and tunable-filter-free. Each ONU comprises a standard semiconductor optical amplifier (SOA), a silicon-based photonic integrated circuit (PIC), and mixed-signal electronic integrated circuits (ICs) performing the signal processing at a relatively slow rate as compared with the overall passive optical network (PON) throughput: digital to analog converters (DACs) and analog to digital converters (ADCs) at 417 MS/s for the home user ONUs.

Indoor location awareness based on received signal strength ratio and time division multiplexing using light-emitting diode light

Abstract: We propose and demonstrate an indoor location awareness method for an autonomous robot vehicle using light-emitting diodes (LEDs). The location is estimated by measuring received signal strength ratio (RSSR), which is the relative ratio of optical powers detected between each LED and optical receiver. In this method, multiple LED lamps on the indoor ceiling are used, which can radiate light only during the individual time slot assigned to each of them. Using the RSSRs, circle or straight line equations are obtained and the crossing point among those equations determines the location of the object. In the experiment, four LED lamps are iden- tified by time-division multiplexing with room dimensions of 1.0 × 1.0 × 1.3 m 3 , and the results show that the mean of the location error is 3.24 cm in the entire floor area. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including

A dual-channel wireless communication system by multiplexing twisted radio wave

Abstract: In order to make full use of current wireless spectrum, we achieve a dual-channel wireless communication system by multiplexing twisted radio wave. In this system, a big challenge is antenna design to generate and combine twisted radio wave. Therefore, firstly, we propose a stacked antenna to achieve this. Secondly, we set up the dual-channel wireless communication system at 8.3 GHz by adopting the antenna. To our knowledge, this is the first time that a wireless communication system multiplexes two modes of twisted radio wave. The experimental results show that the system doubles the spectrum efficiency and reaches a data speed of 1 Gbps with low bit error rate (<;10-7).

Single transceiver-based time division multiplexing multiple-input-multiple-output digital beamforming radar system: concepts and experiments

Abstract: This study presents a time division multiplexing (TDM) multiple-input–multiple-output (MIMO) digital beamforming (DBF) radar concept based on a single transceiver (one transmitter and one receiver). Compared with a conventional MIMO DBF radar system with M-element transmitting array and N-element receiving array, the proposed concept can reduce the number of transmitter/receivers from M + N to 2 for a drastic cost reduction. In addition to theoretical analysis and numerical simulation, an experimental TDM MIMO DBF radar demonstrator is realised and tested for verification using real data. Numerical analysis and experimental results show that the proposed concept can achieve considerable higher angular resolution at lower cost compared to conventional DBF radar concepts using the same antenna array with one-way or two-way beamforming.

On-line reconfiguration system and method based on FPGA

Abstract: The invention discloses an on-line reconfiguration system and method based on an FPGA The method is achieved mainly through the FPGA A standard communication interface module, a memory control module, a high-performance embedded processor core, a reconfiguration function module, a reconfiguration control module and an output interface control module are achieved in the FPGA A high-performance processor embedded into the FPGA is used for being in communication with an upper computer, locally and dynamically configuring the reconfiguration module in the FPGA and transmitting corresponding data to the reconfiguration hardware function module according to different hardware functions, and processed data are output to a peripheral interface unit through the output interface control module By adopting the on-line reconfiguration system and method based on the FPGA, time division multiplexing of various hardware function modules with different functions can be achieved, the utilization ratio of resources in the FPGA of an embedded processing system is improved, and complex hardware function circuits can be achieved through less hardware resources

Long Distance Multi-Mode Communication

Abstract: An optical line terminal (OLT) comprising a receiver configured to couple to a mode coupler via a multi-mode optical fiber that supports more than one optical communication mode, and couple to a plurality of optical network units (ONUs) via the mode coupler, a processor coupled to the receiver and configured to schedule upstream multi-mode transmissions from the ONUs via the multi-mode fiber and the mode coupler by employing time division multiplexing (TDM), and a transmitter coupled to the processor and configured to transmit schedule data to the ONUs.

Energy-efficient optical network units for OFDM PON based on time-domain interleaved OFDM technique

Abstract: We propose and experimentally demonstrate a new scheme to reduce the energy consumption of optical network units (ONUs) in orthogonal frequency division multiplexing passive optical networks (OFDM PONs) by using time-domain interleaved OFDM (TI-OFDM) technique. In a conventional OFDM PON, each ONU has to process the complete downstream broadcast OFDM signal with a high sampling rate and a large FFT size to retrieve its required data, even if it employs a portion of OFDM subcarriers. However, in our scheme, the ONU only needs to sample and process one data group from the downlink TI-OFDM signal, effectively reducing the sampling rate and the FFT size of the ONU. Thus, the energy efficiency of ONUs in OFDM PONs can be greatly improved. A proof-of-concept experiment is conducted to verify the feasibility of the proposed scheme. Compared to the conventional OFDM PON, our proposal can save 17.1% and 26.7% energy consumption of ONUs by halving and quartering the sampling rate and the FFT size of ONUs with the use of the TI-OFDM technology.