广西县级广播电视机构发展路径分析

县级广播电视台,作为我国广播电视系统中最基层的组成部分,受到覆盖面、资金、技术、人才等条件的限制,在央视、省级卫视、省级地面频道、城市台以及互联网视听平台的强势冲击下,一直处于发展滞后的状况。而广西作为全国少数民族人口最多的自治区,境内山多平原少,特别是边境地区、山区、少数民族聚居区存在着基础设施薄弱、制播水平落后、观众需求多样化、受众流失快等问题。那么,广西县级广播电视台如何在面临的窘境下发挥自身的作用。

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.

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.

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.

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.

Efficient Broadcast Retransmission Based on Network Coding for InterPlaNetary Internet

In traditional wireless broadcast networks,a corrupted packet must be retransmitted even if it has been lost by only one receiver.Obviously,this is not bandwidth-efficient for the receivers that already hold the retransmitted packet.Therefore,it is important to develop a method to realise efficient broadcast transmission.Network coding is a promising technique in this scenario.However,none of the proposed schemes achieves both high transmission efficiency and low computational complexity simultaneously so far.To address this problem,a novel Efficient Opportunistic Network Coding Retransmission(EONCR)scheme is proposed in this paper.This scheme employs a new packet scheduling algorithm which uses a Packet Distribution Matrix(PDM)directly to select the coded packets.The analysis and simulation results indicate that transmission efficiency of EONCR is over 0.1,more than the schemes proposed previously in some simulation conditions,and the computational overhead is reduced substantially.Hence,it has great application prospects in wireless broadcast networks,especially energyand bandwidth-limited systems such as satellite broadcast systems and Planetary Networks(PNs).

Cooperative DVB-SH Satellite Broadcasting Systems with Rotated Signal Constellations

In this paper,we study the advantages of cooperation in broadcasting systems from a geosynchronous earth orbit(GEO)satellite to mobile terminals(MTs),achieved through a terrestrial complementary ground station(CGS) with fixed installment,which acts as a relay.Moreover and in the context of the digital video broadcasting-satellite-to-handheld(DVB-SH) standard,the performance improvements offered by the rotated constellations method are investigated,where prior transmission,a phase rotation of the transmitted symbols by a fixed angle is applied followed by a random component interleaver.Turbo codes with soft decision decoding and appropriate random channel interleavers are also considered.We present analytical expressions for the bit log-likelihood ratios(LLRs)that are needed for soft decision decoding at the MT turbo decoder,while the code combining technique is adapted to improve the end-to-end(E2E) performance.Then,we obtain through extensive computer simulations the average bit error probability(ABEP) of quadrature phase-shift keying(QPSK) signals received over pure land-mobile satellite(LMS)and pure CGS links for coding rates 1/3 and6/7.Moreover,the optimal rotation angles are obtained for both links.E2 E ABEP results are then presented assuming cooperation between GEO and CGS,while the power allocation issue is investigated under fixed total transmission power.Our performance evaluation results show that by using the constellation rotation technique,a performance gain can be achieved for high coding rates.

RESEARCH ON GROUPING STRATEGY OF SIP-BASED STREAMING MEDIA P2P LIVE BROADCAST NETWORK

The rapid development of Internet has led to the explosion of information sharing, and how to supervise the sharing is a main research topic on current Internet. Aiming at the disadvantage that the current Peer-to-Peer (P2P) is hard to manage and control, this paper presents a Session Initial Protocol (SIP)-based P2P network of three-level architecture. SIP middleware is introduced to the middle level of the three-layer architecture. By the connection function of the SIP signaling, the P2P transmission on media-level can be controlled. Using SIP’s register and authentication function, the manage layer can manage the whole P2P network. Based on the aforementioned architecture, this paper investigates the grouping strategy on a live broadcast application in P2P network. Combined with the function of SIP register, the paper works on several grouping strategies, sets up models to manage users by grouping them, presents a weight-based K-means IP address grouping algorithm, and realizes it. The experiment shows that the grouping strategy presented in this paper can solve the problem of group sharing of network resource, and can realize the efficient-sharing, reasonable-distributing of network resource.

A Forward-Secure Multi-Receiver Signcryption Scheme

In order to protect historical ciphertext when the private key leaked in the broadcasting system,the forward-secure multi-receiver signcryption scheme is designed based on the generic graded multilinear mapping encoding structure,which effectively prevents illegal access from intruder to the ciphertext in the past time period when the private key in current time period is revealed.Through the generalization of the existing multilinear mapping encoding system,it proposes the generic graded multilinear mapping encoding structure and the generic graded decision Diffie-Hellman problem.Because of the generic graded multilinear mapping encoding system adopted,almost all candidate multilinear mapping encoding systems can automatically adapt to our scheme.Under the assumption of generic graded decision Diffie-Hellman problem,it has proved that the scheme has the information confidentiality and unforgeability in the current time period.After putting forward the security model of forward-secure multi-receiver signcryption scheme,and under the assumption of generic graded decision Diffie-Hellman problem,it has proved that the scheme has the message forward-confidentiality and forward-unforgeability.Compared with other forward-secure public key encryption schemes,the relationship between our scheme and time periods is sub-linear,so it is less complex.

AN EFFICIENT DISTRIBUTED ALGORITHM FOR CONNECTED DOMINATING SET CONSTRUCTION IN WIRELESS SENSOR NETWORKS

Efficient broadcasting protocols based on Connected Dominating Set (CDS) are frequently used;hence the entire broadcast domain is restricted to nodes in the CDS. This letter proves that a node must be a CDS node, if its neighbors with larger keys cannot cover it together.Then a simple distributed CDS construction algorithm is proposed, which is more effective than the existing algorithms in reducing the dominating set size and the computation complexity at the same time. Simulation results also confirm this, especially in relatively dense networks.

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.

Reporting the Reporter： An Evaluation of Health Reporting Among Radio and Television Outfits in Lagos, Nigeria

Radio and television outfits constitute a subset of the mass media belonging specifically to the broadcast system, and vitally provide information useful for development （among others） to its adherents, consumers, and audiences. Health reporting or health news is an aspect of health communication through which the audiences are informed of all matters relating to their total well-being. In this paper, the authors investigated news reporting among broadcast outfits in Lagos-Nigeria as a measure to monitor or watchdog and report the reporter to his clients. The investigation was in two parts： One looked at his strategies in covering and reporting health in the environment; while the other examined news bulletins to subject its health news to a content analysis. The study revealed that health is a neglected concern in broadcast reporting with trigger or vulture approach/practice among broadcast outfits.

Evolution of Webcasting in Nigeria

This paper discusses the history and evolution of webcasting in the Federal Republic of Nigeria as a way of documenting an innovation, a process which thrived on existing system of broadcasting in the country. The paper premised on the webcast phenomenon as an offshoot of broadcasting. It begins by outlining the origins, history, and definitions of webcasting as a global phenomenon before linking these trends to the historical and contemporary context of Nigeria. Adopting the in-depth interview, the paper highlights the motivations for and advantages of using webcasting in Nigeria. It also provides prospects, challenges, and conclusions about the use of this technology within an African context. The paper posits that webcasting as an innovation has gained a firm hold among terrestrial broadcast outfits in the highly populated African country.

AN EFFICIENT APPROACH FOR DVB-H HANDOVER IN DVB-H/UMTS HYBRID NETWORKS

Handover in Digital Video Broadcasting for Handhelds(DVB-H) aims to provide continuous mobile broadcasting services when a user is traveling through cell boundaries.A good handover control can improve the power efficiency and gain much better reception quality.This letter provides a novel approach for DVB-H handover based on DVB-H/Universal Mobile Telecommunications System(UMTS) hybrid network,which moves the main handover function from the terminals to the networks,so that it reduces the operation complexity of the terminals and increases the power saving.When the terminal can not receive the DVB-H signal in the transmission shadow areas or because of some other reasons,the UMTS networks may offer the same service to users to make the service continuous.As the UMTS networks have the topology of the DVB-H networks,by communicating with the terminals,the UMTS networks can help the terminals to predict the handover,and avoid unnecessary handover.

E—SPS数字化安防系统为构建平安监狱保驾护航

前言近几年,安防系统受到了各行各业的高度重视,在监狱、园区、校园、商业建筑等领域得到了大力应用,为用户安全防范发挥了积极的作用。这些高速膨胀的需求,带来的不仅仅是安防行业的蓬勃发展,也给安防企业提出了更高的要求,比如摄像前端数量增多、服务器越来越多、系统越来越臃肿以及系统的稳定性、安全性和设备的维护如何平衡等问题接踵而来,并且目前大多监狱的视频监控系统、门禁系统、报警系统、巡更系统、对讲系统。