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Please follow the links to view the publication.A novel method for illumination and communication using white LED lights
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0149
LED lighting is regarded as the most potential lighting source due to its advantages, such as low power and long lifespan which is largely dependent on the temperature of the LED. So it is possible to predict the life of the LED lamp if the temperature can be read. The conventional method of reading information about a LED lamp is based on communication buses such as RS485 and CAN, but it is inconvenient to add communication lines. This paper proposes a novel compact lighting system which integrates the communication function into the conventional LED driving. Switching frequency modulation method is applied in the system so as to modulate data in the visible light. And the design of the receiver is also proposed, which identifies different frequencies and demodulate data. The introduced system achieves control over communication and dimmer independently at the same time. An experimental system is developed to demonstrate the effectiveness of the proposed approach. (5 pages)Design and FPGA implementation of improved lifting scheme based DWT for OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/ic.2011.0076
In this paper we present the design and FPGA implementation of improved Lifting Scheme based DWT for OFDM Systems. A generic Wavelet based DWT-OFDM for wireless communication is modeled in Simulink for various modulation schemes and wavelets, and analyzed for its BER performances and functionality and compared with Fourier based OFDM (FFT-OFDM) under AWGN Channel. For FPGA implementation of DWT-OFDM. Lifting Scheme architecture is used. Lifting based DWT architecture is better than convolution based DWT architecture in terms of area, power and speed performances. The proposed architecture is modelled using Verilog HDL and verified for its functionality in ModelSim and implemented targeting Virtex-5 FPGA development kit. The estimated frequency of operation of the design is 69.789 MHz, area is 20% of total available area and total power of 1.87907W.Design and performance analysis of DWT/FFT based OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/ic.2011.0072
In this paper, a software reference model for Orthogonal Frequency Division Multiplexing (OFDM) is developed and verified for its functionality that can be adopted for wireless communication applications. BER and functionality of the developed OFDM model is analyzed for Fourier based OFDM (FFL-OFDM) and Wavelet based OFDM (DWL-OFDM) systems for AWGN Channel and results are compared. DWL-OFDM is implemented using zero paddmg and vector transposing for transmitting the OFDM signal and likewise the zeroes are discarded at the receiver. Modulation results for 16-QAM, 32-QAM, 64-QAM, 128-QAM and 256 QAM are noted for both DWL and FFL based OFDM models. It is found that DWL based OFDM achieves better BER results compared with FFL-OFDM model. DWL-IDWL based OFDM model developed is analyzed for its performance by considering various wavelets such as Haar, Db-3, Db-4, bior.3.3, bior5.5, rbior.3.3 and rbior5.5. The OFDM model is developed using Simulink in MATLAB, various test cases have been considered to verify its performance. It is seen that Haar wavelet m DWL-OFDM outperforms FFL-OFDM by approximately 10 dB at a BER of 0.95.A novel modulation classification for PSK and QAM signals in wireless communication
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0636
In this paper, we proposed a new modulation classification algorithm in AWGN channel using fourth order cumulants and improved clustering density spectrum. First, subtractive clustering algorithm is used to classify MPSK and MQAM. Then, a novel algorithm based on the density spectrum of digital signal constellations and cumulants is proposed to internally identify MQAM and MPSK respectively. The peak numbers of in-phase and quadrature density envelope are derived to classify MQAM based on haar wavelet transform. Compared with the existing methods, it is a simple solution with a smaller number of symbols and more modulation types. Simulation results prove the efficiency of the proposed classification algorithm.Seamless amalgamation of full duplex 2.5Gbps wireless and 10Gbps wired optical access networks based on QAM-OFDM technology
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0804
We propose a seamless amalgamation full duplex optical access networks that can provide both 2.5Gbps 16QAM-OFDM wireless and 10Gbps 4QAM-OFDM wired downstream access services for users. A nested Mach-Zehnder module is utilized to realize this integration architecture. And full duplex communication is achieved through using wavelength reuse technique that can carry 2.5Gbps upstream service without any additional optical sources in ONUs. With 20km standard SMF transmission simulation, a dispersion dependent amplitude attenuation is discovered in wireless service part. Using NZ-DSF instead, reliable SER values are obtained and both downstream and upstream services transmission are realized stably.Frequency-octupling millimeter-wave generation based on optical two-step self-heterodyne technique
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1073
A cost-effective frequency-quadrupling scheme which is capable of generating high frequency millimeter-wave (mm-wave) signal is theoretically proposed. By employing optical two-step self-heterodyne technique, this scheme is easy to realize and have a high efficiency. Base on this scheme, a frequency-octupling frequency component is generated. This proposed scheme is a viable solution for the future ultra-high frequency mm-wave applications. (4 pages)The bit error rate performance of MPSK over extended Rayleigh fading channel
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0873
In this paper, the symbol error rate performances of MPSK over extended slow Rayleigh fading channel are studied. Closed expression for MPSK signalling over non-frequency slow fading channels is derived. Since the classical Rayleigh fading channel is a special case of the extended Rayleigh fading channel where the inphase and quadrature components of the corresponding complex-valued Gaussian noise process are statistically independent, the derived expression can be verified by comparison with the results for the classical Rayleigh fading channel. The presented results are useful in studying the performance of digital modulation signals transmission over mobile fading channels.Research on next-generation 40Gbit/s OFDM-PON employing OOK modulated upstream signals
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0809
Novel architecture for next-generation passive optical network (PON) has been proposed and simulated. The proposed architecture is based on wavelength division multiplexing PON in which orthogonal frequency division multiplexing downstream and On-Off Keying upstream modulation are used in each channel. The key new feature of the proposed approach is source-free single-wavelength upstream transmission. Simulation results verify that both 40Gbit/s downstream and 10Gbit/s upstream data transmission are achieved simultaneously.Pilot aided frequency offset estimation and channel estimation for MIMO-OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0656
Orthogonal frequency division multiplexing (OFDM) has been adopted in various wireless communication standards to exploit its high spectral efficiency and robustness against multipath fading channels. Along with the potential benefits of OFDM transmissions, it is very strict on orthogonality. Otherwise, it will introduce inter-carrier interference (ICI). We focus on how to reduce the ICI due to carrier frequency offset (CFO) in multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems in this paper. The influence by residual CFO in the MIMO-OFDM system is analyzed and the residual CFO estimation methods based on pilot subcarriers is presented. According to the simulation results, a proper pilot sequence is selected to make the best performance of the system in the presence of CFO with using the improved methods proposed in the paper.Doppler diversity technique based on pilot-aided channel estimation for OFDM wireless mobile communication
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0717
In the previous works on the traditional Doppler diversity algorithms, it is always assumed that the channel state information is perfect known at the receiver. However, this is not the case in real world. Hence, a novel Doppler diversity technique based on pilot-aided channel estimation for OFDM systems is studied in this paper. The performance of the proposed algorithm decreases if the value of normalized frequency shift is fixed as that in the traditional algorithm. But for the changeable value of normalized frequency shift, the performance is increased. Hence a method how to choose the optimum normalized Frequency shift based on pilot-aided channel estimation is researched in this paper. Finally, the simulation is evaluated to verify the analysis results.Performance evaluation for 60 GHz PAM systems with amplitude detection receiver
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0962
This paper presents an amplitude detection receiver for Pulse Amplitude Modulation (PAM) 60 GHz wireless communication systems. A low complexity non-coherent receiver is employed for amplitude detection. The bit error rate (BER) over an additive white Gaussian noise (AWGN) channel is investigated. Numerical results are presented which show the BER of the amplitude detection receiver.Synchronization for MIMO-OFDM systems based on preamble signals
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0621
An accurate technique for timing and frequency synchronization of multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is proposed in this paper. A new preamble signal which adapts to the MIMO-OFDM synchronization, is derived based on GCL sequences. The carrier frequency offset (CFO) estimation is obtained through taking double correlation operations on the preamble signal, and used in the timing synchronization to gain accurate time estimation. From analysis, it is shown that at the same SNR, the proposed method can reduce the BER and the frame transmission BER of the system compared to the conventional method.Blind SNR estimation for MIMO-OFDM system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0836
This paper deals with the problem of blind signal to noise ratio (SNR) estimation for MIMO-OFDM system. Existing MIMO-OFDM SNR estimators are based on the knowledge of pilot sequences which is not applicable in some environment. A novel blind SNR estimation algorithm for MIMO-OFDM system is proposed. In this algorithm, we first select appropriate Cyclic postfix length of the transmitter signal to ensure that the MIMO channel system can be transformed into a number of single-input single-output (SISO) channel system. Then, based on the cyclostationary statistics of signals, a blind SNR estimation method for SISO is formed. Numerical simulation results are provided to verify the benefit of the proposed method.Effective channel estimation for sparse multipath OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0628
Coherent detection and demodulation need channel state information at receivers for orthogonal frequency division multiplexing systems. Conventional channel estimations, such as least squares (LS), are widely adopted under the assumption of rich multipath. Recently, numerous physical measurements have verified that many wireless multipath channels encountered in practice tend to exhibit sparse structures. Exploiting the inherent sparsity, a novel channel estimation method based on compressive sensing is proposed, which reduces the number of pilots so as to improve the bandwidth efficiency. Simulation results confirm that the proposed method has a 5-dB lower mean square error in channel estimation when compared to the conventional approach. In addition, the complexity of the proposed method is acceptable.Key parameters influence on wavelet based OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0983
IN this paper, we investigate the use of orthogonal wavelet basis functions as an alternative to multicarrier systems based on fast Fourier transform. The influence of the key parameters such as the wavelet decomposition level, the wavelet basis family and the filter order on the receiver detection performance is studied in comparison to the conventional orthogonal frequency division multiplexing. Numerical results conducted over both AWGN and multipath fading channels show that wavelet based OFDM outperforms conventional OFDM in multipath channels in terms of bit error rate. This improvement is examined in the face of different wavelet filter orders and decomposition levels.Simulation of a VLC system with 1 Mb/s NRZ-OOK data with dimming signal
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1068
We report 1 Mb/s data transmission over PWM dimming control signal for a visible light communication (VLC) system based on a simulation. The simulation program is developed using MATLAB and Simulink. In this simulation, the data stream of non-return-to-zero on-off keying (NRZ- OOK) is transmitted together with a dimming signal for brightness control, which has the form of pulse width modulation (PWM). The PWM frame rate is set to 1 kHz to avoid flickering in human eyes. The data rate is set to 20 kb/s and 1 Mb/s. We report eye diagrams of NRZ data streams for 20kb/s and 1Mb/s. (3 pages)An adaptive synchronization algorithm for non-contiguous OFDM cognitive radio systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0856
As a primary way of data transmission in a large variety of cognitive radio systems, Non-Contiguous Orthogonal Frequency Division Multiplexing (NC- OFDM) is a specialized OFDM with non-contiguous sub-carriers. In general, an OFDM system is required to be strictly synchronized. However, one of the huge challenges is the synchronization for NC-OFDM because of the non-contiguous and unevenly distributed sub-carriers of uncertain number in the NC- OFDM. In this paper, we proposed an adaptive synchronization algorithm for NC-OFDM system. In the new scheme, the training sequence is produced adaptively from detected available sub-carriers, and timing metric for synchronization is determined by PN-modulation of the training sequence. The algorithm compensates the frequency offset due to the multi-path channel effect, and yields a single peak on timing metric. A satisfactory performance with regard to estimation on the timing and frequency offset, and to the bit error rate (BER) is shown by simulation.MIMO interference alignment for cognitive radio network
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0973
Though various cognitive radio schemes have been developed, they have not considered the problem of co-channel interference for cognitive users (CU) and primary user (PU)to share a OFDM channel, also well as MIMO-OFDM channel. This paper proposes a scheme that allows PU and CU share a same frequency band, while there are two problems to be solved: the interference of CU to PU, and interference of PU to CU. To solve the first problem, this paper proposes an ICA preceding scheme to cancel the interference of CU to PU, the preceding scheme involves the design of cognitive transmitters. To solve the second problem, this paper proposes CU receiver algorithm, we use inverse matrix to cancel the PU signal interference. The proposed scheme is not limited in the case that a MIMO-OFDM system of cognitive users in a wide spectrum range, and the primary user operates at a narrower channel bandwidth in overlap with the channel of the cognitive user. We designed an ICA CU system as a 2 × 2 MIMO OFDM system, while we need not change the PU systems' design. The simulation of the bit error rate of proposed ICA CU system verifies the proposed scheme.A graph approach for coordinated channel allocation in downlink multi-cell OFDMA networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0666
Radio resource allocation in multi-cell OFDMA (orthogonal frequency-division multiple access) networks is a challenging and practically important problem. In this work we propose a new graph-based sub-channel assignment scheme for downlink multi-cell OFDMA networks. Our scheme consists of two phases, both of which are formulated as graph problems. The first phase is location-aware interference management, including inter-cell interference coordination (IOC) as well as intra-cell interference avoidance. The second phase is channel-aware sub-channel assignment. Simulation results demonstrate that the proposed scheme significantly enhances the system throughput while maintaining user-Quality of Service (QoS) compared with existing sub-channel assignment schemes.Dynamic sectorisation based on genetic algorithms for OFDMA networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0681
OFDMA is the multiple access technique proposed for future communication systems. With growing demands for high data rates radio resource management is an important aspect for OFDMA systems. Sectorisation is one such radio resource management technique that has been proposed as an efficient scheme to improve system performance for GSM, CDMA and OFDMA systems. In this paper, a dynamic sectorisation method based on using a Genetic Algorithm (GA) for OFDMA networks is designed and verified by simulation. The algorithm proposed in this paper can give up to 50% enhancement of system throughput in OFDMA networks for heavily loaded and unbalanced traffic scenarios.Analysis of the impact of Doppler spread on OFDM-based next-generation high-speed rail broadband mobile communications
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0642
With the rapid development of high-speed rail (HSR) around the world in recent years, there is a huge demand for HSR broadband mobile communications to provide passenger information services, and to support sensory data transmission and video surveillance for HSR safety and traffic control. A lot of attention has been paid to the various challenging issues on HSR broadband mobile communications, such as channel estimation and mitigation of significant Doppler frequency spread. Considering the unique characteristics of HSR radio channels, the impact of Doppler spread on inter-subcarrier interference (ICI) for OFDM based next-generation HSR broadband mobile communications is investigated in this paper. Analytical models for the received Doppler power spectrum and the signal-to-interference ratio (SIR) are derived for HSR mobile communications. Simulations have been made for different radio scenarios to reveal the inter-relationship between Doppler power spectrum, Doppler spread, and the resulting SIR.Limited feedback scheme in the presence of feedback delay using Kalman filter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0669
In this paper, a Best-M feedback scheme using Kalman filter is proposed to reduce the uplink feedback overhead in the presence of feedback delay. Best-M feedback scheme is an effective method to reduce the number of the channel quality information (CQI) feedback. However, the CQI feedback after the conventional Best-M decision is inaccurate for base station (BS) scheduling due to the feedback delay and the time varying nature of the channel. A modified limited feedback scheme is proposed to use a Kalman filter to compensate for the performance degradation caused by the feedback delay in Best-M feedback scheme. In the proposed scheme, the user equipment (UE) exploits a Kalman filter to predict the signal to interference plus noise ratio (SINR). Then, the UE makes the Best-M decision based on this predicted SINR and sends the corresponding CQI back to the BS. The simulation results show that the Best-M feedback scheme using Kalman filter, which achieves the same feedback reduction as the conventional scheme, improves the system spectral efficiency.A novel method for improving phase coherence of optical pulse train with fiber nonlinear effects
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1351
A novel method for improving phase coherence of optical pulse train with wavelength conversion based on cross-phase modulation and four-wave mixing effects in the high nonlinear fiber is proposed. The approach is experimentally demonstrated and shows good performation to the MLFL pulse train. (2 pages)Experimentally demonstration of subband-based optical networking on optical superchannel
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1315
We propose subband-based optical networking on optical OFDM or SCFDM superchannels. We experimentally demonstrate the feasibilities of switching and add-drop functionalities on individual subbands with a frequency spacing of 10-GHz. (2 pages)Optical 16QAM modulation based on DD-MZM in radio-over-fiber system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0912
This paper introduces a new scheme to produce millimeter-wave (mm-wave) 16QAM in Base Station (BS) in Radio over Fiber (RoF) system based on Dual-Drive Mach-Zehnder modulators (DD-MZM). The millimeter-wave is generated by OFM (Optical Frequency Multiplication), furthermore the modulation on optical-wave is transferred onto millimeter-wave. Through this scheme the remote local reference signal can be obtained in the Base Station (BS), which lowers the cost of the system. The proposed scheme is proved feasible by theoretical derivation and simulation.Joint carrier and sampling frequency synchronization for OFDM systems
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0652
In this paper, a robust frequency synchronization scheme is proposed for joint estimation of carrier frequency offset (CFO) and sampling frequency offset (SFO) in orthogonal frequency division multiplexing (OFDM) systems. CFO and SFO are simultaneously analyzed in the OFDM system, in which carrier and sampling frequency are generated in a common crystal oscillator. The estimation algorithm is based on phase locked loop (PLL) using one single training symbol. The PLL measures the timing error once a frame in order to track the frequency error to a high degree of accuracy. Extensive simulation is carried out under different channel configurations and the results demonstrate that the proposed algorithm is robust and effective in the estimation of CFO and SFO compared with the other algorithms in the literature.Overview of the receiver techniques for BOC modulation signal
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0967
The binary offset carrier (BOC) modulation offers improved performance and the opportunity for spectrum sharing while retaining implementation simplicity. However its drawback is the ambiguity of the autocorrelation function (ACF), which induces a complexity in the acquisition process, and a risk of biased measures while tracking. The traditional techniques for the classic BPSK modulated signal have to be revised. This paper summarizes the matching receiver techniques for BOC modulation, in order to avoid missed detection and false tracking.Frequency-doubling optoelectronic oscillator based on a polarization modulator
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1356
A frequency-doubling optoelectronic oscillator based on a polarization modulator without the use of an extra laser diode is introduced. The application of the OEO in microwave up- conversion is experimentally verified. (2 pages)Study of millimetre-wave generation based on optical frequency multiplication
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0835
To meet the increasing capacity and mobility as well as decrease the costs in next-generation optical access networks, RoF technology is a promising technique in the emerging optical and wireless convergence network, mm-wave generation is a key technique to realize the convergence network. In this paper, existing optical mm-wave generation technologies are introduced, including direct modulation, optical heterodyning and external modulation. Associated with Shanghai University, a scheme based on Optical Frequency Multiplication employing a dual drive Mach-Zehnder Modulator (DD-MZM) is presented. The novel efficient technique does not require expensive high-frequency electrical equipment. Moreover, no optical filtering is used, which significantly reduces the cost.CM reduction of uplink RS for aggregated carriers in LTE-advanced
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0665
Clustered DFT-S-OFDM has been agreed as the uplink transmission scheme for carrier aggregation (CA) in LTE-Advanced system, so as to extend the bandwidth up to 100MHz and increase the peak data rate. However, clustered DFT-S-OFDM signal suffers from a high cubic metric (CM) due to the large range of signal fluctuation after multiple clustered-carrier modulation. This paper focuses on the CM issue in both inter-band and intra-band CA. More specifically, the effects of reference signal (RS) combination and assignment to CM are investigated. Then, a RS selection scheme is proposed by assigning RSs of different sequence group and different cyclic shifts to component carriers (CCs) and selecting the RSs with the minimum CM. Simulation results show that the proposed scheme obtains lower CM than the conventional scheme where the RSs are randomly selected and assigned.Design of GPS IF signal acquisition and tracking circuits based on FPGA
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0956
This paper presents a FPGA design of a novel GPS IF signal acquisition and tracking circuits, which acquires and tracks the GPS LI frequency and C/A code without FFT and Costas loop. The suggested acquisition circuit consists of 40 branches and each of which acquires 0.5 KHz bandwidth of GPS IF signal. The tracking circuit re-acquires the GPS IF signal based on the SV number and Doppler frequency offered by the acquisition circuit and then tracks the acquired signal by means of a simple dynamic local carrier jumping method proposed in this paper instead of the traditional Costas Loop based method. A unique data demodulation technique that is suitable for the carrier jumping method is also introduced to correctly recover the modulation data. Simulation results and FPGA test show that the proposed design works well for GPS IF signal acquisition and tracking and is promising for low cost and low power FPGA applications for GPS signal processing.FPGA based high speed design for blind equalization of 8PSK signals
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0987
A high speed structure for blind equalization of 8PSK signals is presented based on FPGA. The filter section is designed with a parallel structure based on time-domain convolution. In the case of short delay spread, this structure is superior to the parallel structure based on sub-convolution filter bank in literature on computational complexity. Applying this structure to the blind equalization of 800Mbps 8PSK signals, test results show that the speed requirement is met, the hardware resources are furthest saved, and the blind equalizer converges fast.Investigation of modulation distortion in photonic UWB generation based on a phase modulator
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1350
The influence of large signal modulation on photonic UWB generation based on a phase modulator is investigated. The scheme for monocycle generation has better tolerance to modulation distortion than that of doublet generation. (2 pages)Performance analysis of CFO mitigation algorithms in asynchronous cooperative OFDM communication system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0438
In this paper, we analyze the non-cooperative Orthogonal Frequency Division Multiplexing (OFDM) and Cooperative-OFDM communication system by comparing their performances. Carrier frequency offset (CFO) mitigation is critical for OFDM based co operative transmissions because even small CFO per transmitter may lead to severe performance loss, especially when the number of cooperative transmitters is large. Here, we showed that cyclic prefix (CP) can be exploited to mitigate or even remove completely the CFO. The mitigation performance increases along with the CP length. In particular, long CP with length proportional to N*I, where N is the Fast Fourier Transform (FFT) block length and I is the number of cooperative transmitters, can guarantee a complete CFO removal. While this comes with a reduction in bandwidth efficiency, the long CP in the proposed scheme is exploited to enhance transmission power efficiency in a way similar to spread-spectrum systems, and thus is different from conventional CP that degrades both bandwidth and power efficiency. Here we showed that how performance of mitigation algorithm vary with cyclic prefix length and performance evaluation in case of error up in the estimation of carrier frequency offset (CFO).Comparing the performance of this mitigation algorithm with Orthogonal Frequency Division Multiple Access (OFDMA) mitigation algorithm for different carrier frequency offset values.A novel OFDM-PON architecture based on all-optical waveform and flat frequency comb generation for 100 GB/S optical access
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0868
OFDM-PON has been regarded as a promising solution for next generation PON-based access networks. Meanwhile, the released 40/100G Ethernet standard makes 100 Gb/s fiber transmission to be realized in the near future. We propose a novel OFDM-PON architecture based on all-optical waveform and flat frequency comb generation for 100 Gb/s optical access.Research of OFDM power line carrier communication based on AMI
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0891
AMI (Advanced Metering Infrastructure) is reflected in two-way metering, two-way interoperability on an advanced measurement system. The access network of AMI connecting power utilities to customer's home area network (HAN) promotes the smart metering automation. In such a power line carrier communications medium, the use of OFDM modulation technique is well with the power line carrier communication channel, to effectively resist the power line channel noise, attenuation and time- varying characteristics of the impact. This paper introduces the concept of power line communication, the basic features and principles of the Orthogonal Frequency Division Multiplexing technology (OFDM), focused on analysis of the advantages of OFDM technology used in power line communications.A novel Ethernet over Coax solution employing multi-point control protocol
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0910
A novel EoC (Ethernet over Coax) approach, called ECAN (Ethernet over Coaxial Access Network) is presented in the paper. ECAN is specially designed for the last 100-meter access over coax rather than an adoption from the home network solutions. ECAN employs MPCP (Multipoint Control Protocol) in the media access control layer and uses the single-carrier n-VSB (Vestigial Sideband) modulation in the low frequency band for the bidirectional communication. The basic concept, the implementation architecture and the tested system performances are presented in the paper. It is shown that ECAN can work in different scenarios and provide >100Mbps or up to 130Mbps throughput out of the 160Mbps physical level bit-rate. This proves that ECAN has efficient bandwidth utility, high cost-effectivity and high practicality.System performance analysis of OFDMA based femtocell networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0700
OFDMA femtocells have been proposed as a viable solution not only to deal with the explosive growth of traffic but also to increase energy efficiency of cellular network. However, the system performance of the two-layer femtocell networks is quite different from macrocell networks.In this paper, we first analyze the performance of hierarchical network in terms of system capacity and energy efficiency, especially in the case of introducing sleep mode according to variant network load. Then, we evaluate the users' quality of service (QoS) under different factors, including the distance between macro base station (MBS) and femto base station (FBS), user location, FBS transmission (Tx) power and deployment density. The simulation results show that system capacity and energy efficiency can be improved significantly after FBS deployment and various kinds of factors have effects on users' QoS to different degrees. Our research results provide useful guidelines for the deployment of OFDMA femtocell networks.A cross layer routing protocol for green communication network
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0802
Nowadays, the idea of green communication has been widely discussed to improve the green performance of communication network. Routing is a key issue to reduce the energy consumption of the network. In this paper, we propose a cross layer routing protocol. With the constraint of BER and request rate, the protocol can optimize the adaptive modulation, power control, routing protocol jointly. The simulation results show that the proposed protocol can improve the performance of routing by 15 percent.A multi-user cooperation scheme base on component demodulation
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0678
The combination of spatial diversity and signal space diversity is supposed to provide significant performance boost in communication systems. In this paper, a multi-user cooperation scheme is proposed in order to further exploit the potential of the two kinds of diversity methods. Utilizing constellation expansion and component de-mapping, the proposed system not only helps the destination receiver in combating fading channels, but also enables more users participate in the cooperation flexibly. Moreover, a comparative study between the proposed multi-dimensional scheme and lower order signal space cooperation indicates that an over 4 dB performance gain is achieved.Multi-source cooperative MIMO cognitive network based on distributed interference alignment
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0980
In this paper we proposed a cooperative MIMO cognitive network scheme. This scheme is composed of multiple source node users and multiple relay node users. Based on distributed interference alignment technology, the proposed scheme has broken the existing research on cooperative MIMO cognitive network of single source node user. Both encoding and decoding processes of the proposed scheme are of linear complexity. We derived the symbol error rate of the proposed scheme. In the scenarios of Rayleigh flat fading channel and MPSK modulation, we simulated the receiving symbol error rate of relay node user. The simulation result of the proposed scheme showed that the symbol error rate become zero when SNR is higher than 10dB.QoS aware packet scheduling with adaptive resource allocation for OFDMA based LTE-advanced networks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0660
This paper presents Cross Layer design Packet Scheduling Architecture (CLPSA) with added two functionalities for Long Term Evolution-Advanced (LTE-A) Down Link (DL) transmission. The first function is service specific queue sorting algorithms for service level performance optimisation and second function is adaptive Time Domain (TD) prioritising algorithm for network level performance optimisation. The overall aim is to improve Quality of Service (QoS) of Real Time (RT) and Non Real Time (NRT) streaming video traffic by slightly delaying Best Effort (BE) traffic along with maintaining system throughput and user fairness at good level. The results show that proposed CLPSA significantly reduces delay and Packet Drop Rate (PDR) of RT traffic while satisfying minimum throughout requirement of NRT streaming video traffic. A good trade-off is achieved between system throughput and user fairness.Marginal utility-based power coordination in OFDMA downlink
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0798
In this paper, we address the intercell interference (ICI) in multi-cell networks by dynamically sharing the spectrum through collaboration between base stations. Throughput marginal utility (TMU) is utilized in resource allocation, and a theoretic framework based on TMU optimization is formulated. A distributed power allocation scheme is developed to exploit the average channel statistics of other cells in interference mitigation. The proposed algorithm is shown to substantially outperform conventional schemes.Highly sensitive in-band OSNR monitors based on phase-matched four-wave mixing
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1063
This paper presents a novel all-optical in-band optical signal-to-noise (OSNR) monitoring method based on phase-matched four-wave mixing (FWM). The monitoring ability arises from the power transfer function (PTF) giving preferential gain to clean pulses when compared to noisy pulses. By selecting the phase match condition a much higher monitoring sensitivity can be achieved at a reduced input power compared to other PTF-based methods proposed before. Numerical simulations are used to quantify the sensitivity enhancement for signals with different modulation formats. (3 pages)All optical sampling OFDM scheme with interleaved modulation formats for WDM PON
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1331
An all-optical sampling OFDM with interleaved modulation formats scheme for WDM PON application is proposed. It can flexibly adjust the modulation format and data rate due to different channel performance or different user requirements. This scheme has 80 Gb/s transmission data rate and can coexist with traditional WDM channel. (2 pages)Analysis of modulator impact factors on flat and stable optical comb generation based on re-circulating frequency shifter for all-optical OFDM
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0911
This paper is concerned with the effect of the nonlinearity of a MZM (Mach-Zehnder modulator) on optical OFDM signal distortion. The optical OFDM signal output from the MZM is expressed as a Taylor series including third-order and fifth-order nonlinear distortion terms, by which we can easily establish a mathematical model of the optical OFDM signals in different formats and rates. According to the model, we can get the EVM[1] at the optimized point. Moreover, the proposed theoretical model is proved in good agreement with experiment results of the RoF(Radio over Fiber) system.All-optical OOK-to-DPSK modulation format conversion using XPM in HNLF
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1318
We provide a comprehensive investigation of all-optical modulation format conversion from OOK-to-DPSK at 10 Gb/s using cross-phase modulation. We also present results on OOK-to-DPSK modulation format conversion with wavelength multicasting. (2 pages)A neural approach for overall improvement of OFDM system
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0466
This paper presents a neural network based, high power amplifier (HPA) characteristics independent adaptive method for compensation of nonlinear distortions for orthogonal frequency division multiplexing signals. Major elements that contribute to multipath fading effects are also considered and to account for major degradation categories, Rayleigh and Rician channel models are considered in an OFDM system. System performance is tested for OFDM system with and without neural block and it is proved through spectral regrowth as well as bit error rate (BER) plots that the proposed model brings in overall improvement in OFDM system.Energy saving spectrum selection in cognitive radio networks using stochastic control theory
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0731
Spectrum selection is crucial in improving the performance of cognitive radio networks. Most of previous work on spectrum selection consider spectrum utilization ratio as system design criteria and ignore the energy issue. In this paper, we take a cross-layer design approach to select the optimal spectrum considering the time varying and stochastic nature of wireless channels. The proposed scheme selects one spectrum among different alternatives and sets the modulation and coding scheme and frame size in each time slot according to the channel state, which is modeled as finite-state Markov channel, with the objective of minimizing energy consumption. The procedure of spectrum access is formulated as a restless bandit problem, which can be solved using linear programming (LP) and primal-dual index heuristic algorithm. Simulation results are presented to show the performance improvement of the proposed scheme.A data-aided OFDM/OQAM synchronization algorithm using maximum posterior probability criterion
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0640
The OFDM/offset QAM (OFDM/OQAM) systems are sensitive to synchronization errors. To overcome this shortage of OFDM/OQAM systems, in this paper, a data-aided joint symbol timing and carrier frequency offsets (CFO) estimation algorithm based on maximum posterior probability criterion is proposed. Compared to traditional data aided algorithms, the derived algorithm achieves better performance in multipath fading channels in terms of capture probability of symbol timing offsets, root mean square error (RMSE) of CFO estimation and bit error rate (BER) versus signal-to noise power ratio (SNR).