关于新常态“广播+”发展的思考

在广播与互联网融合发展后,广播迎来了新时代——"广播+"。目前"广播+"已是广播事业的一种新常态。如何让广播始终保持舆论导向引领者的地位,使其始终深受民众欢迎并获得更大的发展空间,需要广播人用心思考。本文结合广东广播电台的实践,谈谈关于新常态下"广播+"发展的一些体会。

Programming Technology of IP Multicast and Broadcast Based on Socket

Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.

Wireless location algorithm using digital broadcasting signals based on neural network

In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.

Digital broadcast channel estimation with compressive sensing

In order to reduce the pilot number and improve spectral efficiency, recently emerged compressive sensing （CS） is applied to the digital broadcast channel estimation. According to the six channel profiles of the European Telecommunication Standards Institute（ETSI） digital radio mondiale （DRM） standard, the subspace pursuit （SP） algorithm is employed for delay spread and attenuation estimation of each path in the case where the channel profile is identified and the multipath number is known. The stop condition for SP is that the sparsity of the estimation equals the multipath number. For the case where the multipath number is unknown, the orthogonal matching pursuit （OMP） algorithm is employed for channel estimation, while the stop condition is that the estimation achieves the noise variance. Simulation results show that with the same number of pilots, CS algorithms outperform the traditional cubic-spline-interpolation-based least squares （LS） channel estimation. SP is also demonstrated to be better than OMP when the multipath number is known as a priori.

Employing temporal channel correlation in user selection for MIMO broadcast systems

Taking the time varying nature of wireless channels into account, two user selection schemes with lower complexity are developed for multiple-input multiple-output broadcast （MIMO BC）systems. According to the relationship between coherence time and Doppler frequency, an information frame is divided into several segments. At the beginning of each segment, the user selection is carded out with the greedy selection algorithm. In the simplified user selection algorithms employing the temporal correlation （SUSTC）, the selection results are applied for all the remaining slots in each segment. But in the improved simplified user selection algorithms employing the temporal correlation（ISUSTC）, at the remaining slots, users are kept with favorable channel conditions selected at the previous slot, and other users are updated from the candidate pool to communicate simultaneously. Simulations show that compared with the greedy user selection method, the proposed algorithms can reduce the selection complexity with a little sum capacity loss.

Improved approach to enhanced Internet connectivity for mobile ad hoc networks

An improved internetworking approach is proposed to enhance the Internet connectivity which is deteriorated due to unidirectional links and blind rebroadcasting of gateway discovery packets for mobile ad hoc networks. The hybrid gateway discovery scheme that combined the advantages of a proactive and reactive gateway discovery approach is used to achieve high connectivity while keeping overhead costs low. By exchanging ad hoc on-demand distance vector （AODV） hello packet which includes additional fields named symmetric neighbor list and asymmetric neighbor list, unidirectional links are removed from route computation and broadcast storm can also be relieved simultaneously. Performance results using ns-2 simulations, under varying numbers of unidirectional links and node speeds, show that this improved Internet connectivity approach can provide better performance than others.

0.18μm CMOS programmable frequency divider design for DVB-T

The implementation of a programmable frequency divider, which is one of the components of the phase-locked loop （PLL） frequency synthesizer for digital video broadcastingterrestrial （DVB-T） and other modem communication systems, is presented. By cooperating with a dual-modulus prescaler, this divider can realize an integer frequency division from 926 to 1 387. Besides the traditional standard cell design flow, such as logic synthesis, placement and routing, the interactions between front-end and back-end are also considered to optimize the design flow under deep submicron technology. By back-annotating the back-end information to front-end design, a custom wire-load model is created which is more practical compared with the default model. This divider has been fabricated in TSMC 0. 18μm CMOS technology using Artisan standard cell library. The chip area is 675 μm × 475 μm and the power consumption is about 2 mW under a 1.8 V power supply. Measurement results show that it works correctly and can realize a frequency division with high precision.

A High Linearity CMOS DVB-S Front-End

A direct conversion CMOS DVB-S front-end employs a T-configuration variable attenuator,a single-to- differential low noise amplifier, and a low noise mixer. By innovative use of the attenuator, the linearity handling ability of the system is dramatically improved. The system is designed and fabricated in SMIC 0.18 μm RF CMOS technology. The measurement data show that the front-end provides a total of more than 30rib dynamic range and a noise figure of 5dB in the wide frequency signal band. The prototype front-end consumes only 10mA and achieves an IIP3 of ＋ 20dBm.

ADS-B Anomaly Data Detection Model Based on Deep Learning and Difference of Gaussian Approach

Due to the influence of terrain structure,meteorological conditions and various factors,there are anomalous data in automatic dependent surveillance-broadcast(ADS-B)message.The ADS-B equipment can be used for positioning of general aviation aircraft.Aim to acquire the accurate position information of aircraft and detect anomaly data,the ADS-B anomaly data detection model based on deep learning and difference of Gaussian(DoG)approach is proposed.First,according to the characteristic of ADS-B data,the ADS-B position data are transformed into the coordinate system.And the origin of the coordinate system is set up as the take-off point.Then,based on the kinematic principle,the ADS-B anomaly data can be removed.Moreover,the details of the ADS-B position data can be got by the DoG approach.Finally,the long short-term memory(LSTM)neural network is used to optimize the recurrent neural network(RNN)with severe gradient reduction for processing ADS-B data.The position data of ADS-B are reconstructed by the sequence to sequence(seq2seq)model which is composed of LSTM neural network,and the reconstruction error is used to detect the anomalous data.Based on the real flight data of general aviation aircraft,the simulation results show that the anomaly data can be detected effectively by the proposed method of reconstructing ADS-B data with the seq2seq model,and its running time is reduced.Compared with the RNN,the accuracy of anomaly detection is increased by 2.7%.The performance of the proposed model is better than that of the traditional anomaly detection models.

Vehicular Beacon Broadcast Scheduling Based on Age of Information(AoI)

Vehicular beaconing plays an important role to facilitate various applications in the paradigm of Internet of Vehicles(IoV). Due to high dynamic and resource limitation in IoV, how to schedule the vehicular beacon broadcast is challenging, especially in dense scenarios. In this paper, we investigate the beacon broadcast scheduling problem considering the Age of Information(AoI). We first propose an algorithm minimizing the expected sum of AoI considering the limited communication resource and vehicle mobility. Then the performance of the proposed algorithm is analyzed. With the proposed algorithm, the optimal solution can be obtained under certain conditions. Extensive simulations are conducted to verify the efficiency, effectiveness and fairness of the proposed solution.

A smartcard conditional access interface scheme for conditional access subsystem separation in digital TV broadcasting

Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.

BROADCAST SCHEDULING WITH MIMO LINKS IN MULTI-HOP AD HOC NETWORKS

As the current medium access control protocols with Multiple Input Multiple Output （MIMO） links only bear point to point service, broadcast scheduling algorithm in ad hoc networks with MIMO links is proposed. The key to the proposed broadcast scheduling algorithm is the time slot scheduling algorithm which guarantees collisi~）n-free transmissions for every node and the mini- mum frame length. The proposed algorithm increases the simultaneous transmissions of MIMO links efficiently. Due to the interference null capacity of MIMO links, the interference node set of each node can decrease from two-hop neighbors to one-hop neighbors possibly. Simulation results show that our algorithm can greatly improve network capacity and decrease average packet delay.

PVC Membrane Selective Electrode for Determination of Cadmium(Ⅱ) Ion in Chocolate Samples

Benzil bis(carbohydrazone)(BBC) is prepared and explored as new N N Schiff's base, which plays the role of an excellent ion carrier in the construction of a Cd(II) ion membrane sensor. The tris(2-ethylhexyl) phosphate best performance corresponds to a membrane composition of 30% poly(vinyl chloride), 65%(TEHP), 3.5% BBC and 1.5% tetradodecyl-ammoniumtetrakis(4-chlorophenyl) borate(ETH 500). This sensor shows very good selectivity and sensitivity towards cadmium ion over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition, selectivity, pH and influence of additive on the response properties of electrode were investigated. The response mechanism was discussed in the view of UV-spectroscopy. The electrode exhibits a Nernstian behavior(with slope of 29.7 mV per decade) over a very wide concentration range from 1.0×10?1 to 1.0×10?8 mol·L?1 with a detection limit of 3.2×10?8 mol·L?1. It shows rela-tively fast response time in whole concentration range(<8 s) and can be used for at least 10 weeks in the pH range of 2.0-9.0. The proposed sensor is successfully used for the determination of cadmium in different chocolate sam-ples and as indicator electrode in titration with ethylene diamine tetraacetate(EDTA).

DIFFERENTIAL AMPLITUDE PHASE SHIFT KEYING: A NEW MODULATION METHOD FOR TURBO CODE IN DIGITAL RADIO BROADCASTING

The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.

New algorithm for variable-rate linear broadcast network coding

To adjust the variance of source rate in linear broadcast networks, global encoding kernels should have corresponding dimensions to instruct the decoding process. The algorithm of constructing such global encoding kernels is to adjust heterogeneous network to possible link failures. Linear algebra, graph theory and group theory are applied to construct one series of global encoding kernels which are applicable to all source rates. The effectiveness and existence of such global encoding kernels are proved. Based on 2 information flow, the algorithm of construction is explicitly given within polynomial time O（｜E｜ ｜T｜.ω^2max）, and the memory complexity of algorithm is O（｜E｜）. Both time and memory complexity of this algorithm proposed can be O（ωmax） less than those of algorithms in related works.

Four-Party Quantum Broadcast Scheme Based on Aharonov State

In this paper,we propose a solution based on four-qubit Aharonov state to an old problem by using the property of congruence.The proposed scheme may realize the broadcast among four participants,therefore,it makes progress to the three-party broadcast realized previously.Using pairwise quantum channels and entangled qubits,the detection between these players also can be accomplished.Finally,the feasibility of the protocol and the analysis of security are illustrated.

DVB-S2 inner receiver design for broadcasting mode

This paper details on the design of DVB-S2 receivers which is compliant with the broadcasting mode. Special at-tention is paid to the specific receiver functions necessary to demodulate the received signal. To show the system performance we consider the design of a complete receiver consisting of timing recovery unit, frame synchronization unit, frequency recovery unit and phase recovery unit. The system is easier to hardware implementation comparing with that provided in (ETSI, 2005; Sun et al., 2004). After the performance of the algorithms is analyzed and a quantitative result is given, this allows us to draw conclusions concerning the achievable system performance under realistic complexity assumptions.

Effective multicasting algorithm for dynamic membership with delay constraint

This paper proposes an effective heuristic algorithm The tree constructed by DDMR has the following characteristics： for dynamic multicast routing with delay-constrained DDMR. （1） multicast tree changes with the dynamic memberships; （2） the cost of the tree is as small as possible at each node addition/removal event; （3） all of the path delay meet a fixed delay constraint; （4） minimal perturbation to an existing tree. The proposed algorithm is based on “damage” and “usefulness” concepts proposed in previous work, and has a new parameter bf（Balancing Factor） for judging whether or not to rearrange a tree region when membership changes. Mutation operation in Genetic Algorithm （GA） is also employed to find an attached node for a new adding node. Simulation showed that our algorithm performs well and is better than static heuristic algorithms, in term of cost especially.

TDOA Localization Algorithm with Compensation of Clock Offset for Wireless Sensor Networks

This paper presents a source localization algorithm based on the source signal's time-difference-of-arrival(TDOA) for asynchronous wireless sensor network.To obtain synchronization among anchors,all anchors broadcast signals periodically,the clock offsets and skews of anchor pairs can be estimated using broadcasting signal's time-of-arrivals(TOA) at anchors.A kalman filter is adopted to improve the accuracy of clock offsets and track the clock drifts due to random fluctuations.Once the source transmits signal,the TOAs at anchors are stamped respectively and source's TDOA error due to clock offset and skew of anchor pair can be mitigated by a compensation operation.Based on a Gaussian noise model,maximum likelihood estimation(MLE) for the source position is obtained.Performance issues are addressed by evaluating the Cramer-Rao lower bound and the selection of broadcasting period.The proposed algorithm is simple and effective,which has close performance with synchronous TDOA algorithm.

PERFORMANCE OF THE ZERO FORCING PRECODING MIMO BROADCAST SYSTEMS WITH CHANNEL ESTIMATION ERRORS

In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum ca- pacity and BER performance are consistent with those of the perfect Channel State Information (CSI) with only a performance degradation.