Local Broadcast Research Articles

Efficient Local Broadcasting in Wireless Ad Hoc Networks Using Dynamic Approach

Broadcasting is a commonly used feature in wireless ad hoc networks. It is a common operation for route establishment and for sending control and emergency messages. The primary goal of broadcasting is to successfully reduce the number of transmissions that are required to achieve full delivery with energy consumption using local broadcast algorithm. In static approach, using the local topology information, the local algorithm determines the status of each node and also the priority function. Using this approach it is not possible to achieve the good approximation factor to the optimum solution. The hybrid local broadcast algorithm based on dynamic approach is proposed for guarantee with full delivery and successful approximation to the optimum solution without considering the node position. In dynamic approach the position of the node is determined “on-the-fly” based on local topology information. So, it is possible to get the good approximation factor to the optimum solution. The position information is the solution for getting good approximation factor. But in some applications it may not be possible to get position information because of the sheer nature of ad hoc networks that allow mobility cause dynamic, unpredicted and frequent topology changes. In those situations also the proposed local broadcast algorithm can achieve both full delivery and a constant approximation to the optimum solution in which the status of each node is decided “on-the-fly” (i.e. reactive protocol).

SOBP: a sender-designated opportunistic broadcast protocol for VANET

Two problems existing in highway vehicular ad hoc networks (VANET), i.e., the slow reaction problem (SRP) and the local broadcast storm problem (LBSP), are investigated. In SRP, a candidate forwarder (CF) close to a sender always rebroadcasts a packet with a low probability or rebroadcasts a packet after a long delay in sparse network, while LBSP occurs when vehicles contending for accessing channel in a local dense network. To solve these problems, a Sender-designated Opportunistic Broadcast Protocol (SOBP) is proposed, which has multiple CFs to broadcast packets and is irrelevant to node density. A sender designates a fixed number of CFs and assigns priorities to them before broadcasting a packet so that possible collisions in the receivers are avoided. To enhance the efficiency of a single transmission, the sender chooses the CFs separated with a certain distance to alleviate the effect of hidden node. The average number of transmissions in a successful broadcast is analyzed and the retransmission strategy to enhance the reliability is presented. One of the main features of SOBP is that it is able to keep broadcasting overhead at a low level. Simulations show that SOBP is able to effectively solve the SRP and the LBSP.

When pictures waste a thousand words: analysis of the 2009 H1N1 pandemic on television news.

ObjectivesEffective communication by public health agencies during a pandemic promotes the adoption of recommended health behaviours. However, more information is not always the solution. Rather, attention must be paid to how information is communicated. Our study examines the television news, which combines video and audio content. We analyse (1) the content of television news about the H1N1 pandemic and vaccination campaign in Alberta, Canada; (2) the extent to which television news content conveyed key public health agency messages; (3) the extent of discrepancies in audio versus visual content.MethodsWe searched for “swine flu” and “H1N1” in local English news broadcasts from the CTV online video archive. We coded the audio and visual content of 47 news clips during the peak period of coverage from April to November 2009 and identified discrepancies between audio and visual content.ResultsThe dominant themes on CTV news were the vaccination rollout, vaccine shortages, long line-ups (queues) at vaccination clinics and defensive responses by public health officials. There were discrepancies in the priority groups identified by the provincial health agency (Alberta Health and Wellness) and television news coverage as well as discrepancies between audio and visual content of news clips. Public health officials were presented in official settings rather than as public health practitioners.ConclusionThe news footage did not match the main public health messages about risk levels and priority groups. Public health agencies lost control of their message as the media focused on failures in the rollout of the vaccination campaign. Spokespeople can enhance their local credibility by emphasizing their role as public health practitioners. Public health agencies need to learn from the H1N1 pandemic so that future television communications do not add to public confusion, demonstrate bureaucratic ineffectiveness and contribute to low vaccination rates.

The Rise of Quasi-Common Carriers and Conduit Convergence

The technologies that deliver content to consumers have begun to converge into a single Internet-driven conduit. Such convergence supports a consolidation of previously stand alone markets as evidenced by the ability of ventures to offer a “triple-play” bundle of Internet-delivered video, data and telephone service. Converging technologies and markets eliminate a sharp and identifiable distinction between the service classifications created by Congress and applied by the Federal Communications Commission (“FCC”). The Commission faces a regulatory quandary in maintaining a clear regulatory dichotomy between carriers operating as private conduits versus carriers subject to government oversight. The former can deliver content, software and services largely free of government regulation while some in the latter category operate as common carriers bearing public utility obligations, while others incur FCC-mandates to carry video content and place it on particular channel locations. This paper will examine whether and how converging technologies and markets provide an opportunity for the FCC to impose more forms of quasi-common carrier duties on ventures that otherwise would qualify for limited or no regulation. The paper will examine a recent court affirmance of the FCC’s requirement that all cellphone companies provide subscribers of other carriers “roaming” access to data services, despite the classification of Internet access as a largely unregulated information service. The paper also will examine previous instances where courts have affirmed FCC decisions to impose quasi-common carrier duties, such as the mandatory carriage of local broadcast television signals. The paper shows how the FCC has found ways to impose quasi-common carrier duties on ventures providing convergent services even though these ventures appear to qualify for little, if any, regulation. The FCC may have devised ways to respond to changed circumstances and the rigidness of congressionally crafted service definitions. However such flexibility generates regulatory uncertainty and the potential for the Commission to exceed its statutory authority. The paper concludes that the FCC will consider applying quasi-common carrier duties on private carriers without certainty about the permissible reach of this option.

Drug Shortages: The Survey Says . . .

My daughter is graduating from high school and has completed her university application. She will be enter ing a pre-pharmacy program and is thinking about a career in hospital pharmacy, so perhaps the apple really doesn’t fall too far from the tree. I recall the upheaval that her starting school a dozen years ago created in our family. Every year, she became involved in more scholastic and extracurricular activities. As the associated parental work increased, our ability to accomplish the tasks also grew, in part because we gave up other activities. In many ways, the Canadian drug shortage situation has had the same effect on pharmacists. The Canadian Society of Hospital Pharmacists (CSHP) recently joined the Canadian Pharmacists Association and the Canadian Medical Association in surveying members about drug shortages and releasing a statement about the results to the media. 1 If you missed it on your local news broadcast, don’t feel bad: media pick-up of the story was limited and so was the interest of our politicians. Perhaps what was missing from the story was the aspect of potential patient harm. The diligent and timely mitigation of drug shortages by hospital and community pharmacists and by physicians has resulted in many positive patient outcomes, but these tend not to make great news stories. Survey results indicated that up to 20% of patients have been affected by shortages. The top 3 impacts for patients were delayed access to needed medication, use of a less effective medication or formulation, and increased risk of adverse effects. Hospital pharmacists who responded to the survey indicated that patients experienced delays in acquiring their medications, additional cost associated with alternative medications, and confusion related to changes in medication or formulation. Of 215 hospital pharmacists who responded, more than half reported trouble sourcing a medication for a patient during their most recent shift, and almost two-thirds indicated difficulty getting a medication in the previous week. Hospital pharma cists’ strategies to mitigate the effects of drug shortages included communication within the pharmacy, hospital, and health region; rationing or restricting the use of existing supplies; obtaining medications from another source; compounding

Error Control for Local Broadcasting in Heterogeneous Wireless Ad Hoc Networks

Local (single-hop) broadcasting is widely employed in distributed protocols (e.g., neighbor discovery, local information exchange in distributed network optimization and gossip-based algorithms) in wireless ad hoc networks. The performance of local broadcasting is characterized by the mean number of neighbors and the probability distribution of the number of neighbors of a broadcasting node. In this paper, we study the performance of local broadcasting in heterogeneous wireless ad hoc networks in which inter-system interference dominates signal reception quality, considering general fading distributions of both the desired signal and the interfering signals. In addition, we investigate the impacts of different error control techniques (e.g., simple retransmission, Chase combining, and incremental redundancy) on the performance of local broadcasting. The increase in the mean number of neighbors of a broadcasting node with respect to the number of retransmissions of a message is clarified, facilitating QoS provisioning in reliable local broadcasting in interference-limited heterogeneous wireless ad hoc networks.

Pluralism in crisis: Transformations of the spanish DTT market in the context of the recession

This article discusses the most significant aspects of DTT’s evolution in Spain since the analogue switch-off in April 2010. It underscores the severe cutbacks affecting public service television broadcasters and their impact, as well as a return to government control over the Spanish Broadcasting Corporation (RTVE) in particular. It also emphasizes the major tendency towards concentration in the national private DTT market and the inviability of most regional and local broadcasters. All of these issues are analysed from the perspective of their worrying impact on pluralism.

Rebels with a pen: observations on the newly emerging media landscape in Libya

The role of social media as a catalyst of the ‘Arab Spring’ has been subject to much debate – both by academics and the press. Likewise, the impact of international media, such as Al-Jazeera, has been thoroughly examined elsewhere. While acknowledging the significance of these players, this article explores the emergence of a new landscape of local print and broadcast media in revolutionary Libya that is both the result of the dramatic changes that the country has undergone and one of their facilitators. This article analyses the political impact of these new forms of media during and after the 2011 Libyan uprisings, with an emphasis on how the role and the self-image of journalists and media producers has evolved alongside with Libya's political transformation. It is demonstrated that the new Libyan media began their life as ‘partisan advocates’ and that different societal currents are now struggling to set the new role of media. It concludes with an analysis of the newly implemented legal framework and institutions which govern the Libyan media. It remains unclear if recent legislation will protect independent media from the authorities or, conversely, allow the state to exert censorship and consolidate its ownership over the media. This article analyses the various approaches to media jurisdiction prevalent in post-Qadhafi Libya as reflecting various degrees of state intervention. This discussion reflects the inherent contradictions of a society which, with very little preparation, has had to manage the change from conditions of absolute governmental control to conditions of relative anarchy.

The Impact of 2008 Presidential Campaign Media on Latinos

To examine the effects of the 2008 Obama campaign’s targeted media effort aimed at Latino voters, we married 2008 campaign media data from multiple sources to survey data on registered Latino voters in Nevada and Arizona to examine the specific impact of advertisement buys on that population. In the presence of controls, Obama’s media spending advantage over McCain had a significant and positive relationship with an Obama vote. When looking at local broadcast, cable and radio specifically, we find a significant relationship between spending differentials on local broadcast advertising and vote intention but not between spending differentials on radio and cable buys.

A Framework For Handling Local Broadcast Storm Using Probabilistic Data Aggregation In VANET

Data aggregation is used to combine correlated data items from different vehicles before redistributing to other vehicles in the vehicular ad hoc networks (VANET). The number of retransmissions and the communication overhead can be reduced considerably by using aggregation. It is a prerequisite for applications that require periodic dissemination of information into a large region so that, drivers can be informed well in advance and can take alternative route in case of traffic congestion. Dissemination of information to vehicles through broadcasting creates a broadcast storm problem in VANET. In this paper a novel framework is proposed for handling the local broadcast storm problem using probabilistic data aggregation which reduces the bandwidth consumption and hence improves the information dissemination. This system exploits the knowledge base and stores the decisions for aggregation and is based on a flexible and extensible set of criteria. These criteria's can be application specific and can enable a dynamic fragmentation of the road according to the various application requirements. The framework is evaluated for VANET based traffic information system through simulation for strictly limited bandwidth and local broadcast problem. The results demonstrate that completely structure-free probabilistic data aggregation reduces the bandwidth consumption by eliminating the local broadcast problem.

Influence of the pr services of local governments on the editorial policy of online editions of local public broadcasters: Case studies: Radio Bijelo Polje and Radio Tivat

The paper explores the extent of influence of the services for public relations of local governments on the editorial policy of the online editions of local public broadcasters, namely the two radio stations of Radio Bijelo Polje and Radio Tivat. For this paper we set up a special code sheet with categories whose analysis will show how public relations affect the editorial policy of the mentioned media. The analysis refers to the period from the May 1st to May 31st, 2013. We have used a quantitative and qualitative method, the content analysis method and the comparative method. We have also explored how these media handle the press or media releases distributed by the local government. Also, we have explored the sources of information of these media, if the local governments had just placed a formal content, and whether any concealed impact of local governments on the local media was detected. The local governments of Bijelo Polje and Tivat are identically structured so the paper explains how they work and how they use the local media. Knowing that both local authorities have services for public relations, we have explored the scope of their activities and responsibilities accorded to them by the municipal regulations.

A Timed Calculus for Mobile Ad Hoc Networks

We develop a timed calculus for Mobile Ad Hoc Networks embodying the peculiarities of local broadcast, node mobility and communication interference. We present a Reduction Semantics and a Labelled Transition Semantics and prove the equivalence between them. We then apply our calculus to model and study some MAC-layer protocols with special emphasis on node mobility and communication interference. A main purpose of the semantics is to describe the various forms of interference while nodes change their locations in the network. Such interference only occurs when a node is simultaneously reached by more than one ongoing transmission over the same channel.

At the Digital Watershed: Terrestrial Television Broadcasting in Japan

The switch to digital terrestrial broadcasting on 24 July 2011 marked a watershed for the broadcasting industry in Japan. Digitalisation is the single largest industry-wide event since the advent of alternative distribution technologies, satellite and cable, in the 1980s. Preparation for the switch to digital, known as chideji-ka, has put existing business arrangements under pressure and has led to a renewed focus on the future shape of the industry. There is increasing acknowledgement that change, especially in the relationship between central and local broadcasters, is inevitable. This paper summarises the position of the industry at the beginning of its digital age, arguing for a new view of broadcasting in Japan that recognises the two-tier reality behind industry rhetoric. It also summarises the major options open to the industry as it looks to redefine itself in a much-changed media environment.

DRM과 DRM+ 기반의 AM/FM 디지털라디오 활용 연구

In this paper, the possibility and necessity of the digital broadcasting propulsion in AM and FM is presented based on DRM and DRM+ transmission modes, They are the members of series technological family in digital radio development. As the frequency utilization, the application of DRM+ is flexible in any mode such as IN-BAND or OUT-OF-BAND. When the digital audio broadcasting is planned at LOW-VHF bandwidth such as TV channel No.5 and NO.6 being adjacent to FM band and OUT-Of-BAND DRM+ technology is applied, there is no collision and jamming. Particularly, in the IN-BAND Hybrid mode, it is mentioned that there was the difficulty problem for multiple SFN transmitters uses. Not like the IN-BAND mode the OUT-OF-BAND mode lets multiple transmitters, because neighbor transmitters do not interfere each other. Digital transmitter can be combined with the existing FM transmitter. The intensity of power and size of area can be easily determined according to local broadcasters` condition. And the OUT-OF-BAND mode is advantageous for AM/FM integration in digital radio receiver manufacturing, which makes the conversion schedule much shorter.

Quantum-correlation breaking channels, broadcasting scenarios, and finite Markov chains

One of the classical results concerning quantum channels is the characterization of entanglement-breaking channels [M. Horodecki, P. W. Shor, and M. B. Ruskai, Rev. Math. Phys. 15, 629 (2003)]. We address the question whether there exists a similar characterization on the level of quantum correlations which may go beyond entanglement. The answer is fully affirmative in the case of breaking quantum correlations down to the, so-called, QC (quantum-classical) type, while it is no longer true in the CC (classical-classical) case. The corresponding channels turn out to be measurement maps. Our study also reveals an unexpected link between quantum state and local correlation broadcasting and finite Markov chains. We present a possibility of broadcasting via non von Neumann measurements, which relies on the Perron-Frobenius theorem. Surprisingly, this is not the typical generalized controlled-not (c-not) gate scenario appearing naturally in this context.

A state-based model of sensor protocols

We introduce a state-based model that can be used in specifying and verifying the desired properties of sensor network protocols. This model accommodates several characteristics that are common in sensor networks. Examples of these characteristics are unavoidable local broadcast, probabilistic message transmission, asymmetric communication, message collision, and timeout actions and randomization steps. We also propose three methods for analyzing a sensor network protocol specified in the model. In the first method, called nondeterministic analysis, a specified sensor network protocol is shown to be “nondeterministically correct” under the assumption that message delivery is assured and message collision is guaranteed not to occur. In the second method, called probabilistic analysis, the protocol is shown to be “probabilistically correct” under the assumption that message delivery is probabilistic but message collision is guaranteed not to occur. In the third method, called collision analysis, the effect of message collision and probabilistic message delivery on the correctness of the protocol is analyzed. To demonstrate the utility of our model, we discuss an example protocol that can be used by a sensor to identify its strong neighbors in the network, and apply the analysis methods to the protocol. Using our model, we also show that the protocol satisfies a desirable property, called self-stabilization property.

From key predistribution to key redistribution

One of crucial disadvantages of key predistribution schemes for ad hoc networks is that if devices A and B use a shared key K to determine their session keys, then any adversarial device that holds K can impersonate A against B (or vice versa). Also, the adversary holding such a device can eavesdrop on communication between A and B for the lifetime of the system.We develop a dynamic scheme where the devices are preloaded with permanent keys according to a predistribution scheme, but these keys are not used directly for setting up session keys. For this purpose devices use a pool of temporal keys, which periodically are selected at random by a system provider. The temporal keys are broadcast by the system provider in an encrypted form (e.g. using the GSM network or local broadcasting services). For the transmission, the temporal keys are encrypted with permanent keys, each temporal key occurring m times encrypted with m different permanent keys. (Parameter m is a small constant.)Encrypting the same temporal key with different permanent keys has the effect that with a high probability two devices share many more temporal keys than the permanent keys from the main pool of keys. Also, the shared temporal keys come not only from ciphertexts encrypted with shared permanent keys but predominantly from ciphertexts encrypted with the permanent keys that are not shared by the devices. After each re-distribution different pairs of permanent keys provide such shared temporal keys. This feature is the key property of our design. It makes it possible not only to protect communication against an adversary that has collected a large fraction of keys from the main pool of keys, but also enables using key predistribution for authentication in the presence of such an adversary.Finally, we present a scheme for renewing the permanent keys in a way that an adversary loses the knowledge of permanent keys except for the keys that it learns via the legitimate devices that he holds. The scheme is based on projective plane techniques.

American media, intercultural stories and the 2004 Olympic flame ceremonies

This paper explores backstage conventions and conditions for national and local broadcasting of the Olympic Games. While the Olympic Movement sees sport as a means to the larger end of intercultural understanding, American media largely frame the Games as a competition among nations for the glory of athletic victory and superiority. ‘Covering’ the Olympics within this dominant framework leads the American broadcaster National Broadcasting Corporation (NBC) to a studied disinterest in intercultural stories, becoming itself a roadblock to understanding foreign cultures and the Olympic ethos, rituals and symbols. The author, a Greek-American and local NBC employee at the time of the Athens 2004 Olympics, describes her struggles to generate intercultural programming and interprets NBC's refusal to allow American audiences to view the 2004 flame-lighting ceremonies at Ancient Olympia and the relay through Greece as lost opportunities to temper the stereotyping of host cultures for the American public.

The role of coding in the choice between routing and coding for wireless unicast

We consider the benefits of coding in wireless networks, specifically its role in exploiting the local broadcast property of the wireless medium. We first argue that for unicast, the throughput achieved with network coding is the same as that achieved without any coding. This argument highlights the role of a general max-flow min-cut duality and is more explicit than previous proofs. The maximum throughput can be achieved in multiple ways without any coding, for example, using backpressure routing, or using some centralized flow scheduler that is aware of the network topology. However, all such schemes, in order to take advantage of the local broadcast property, require dynamic routing decisions for choosing the next hop for each packet from among the nodes where it is successfully received. This choice seems to depend critically on feedback signaling information like queue lengths, or ARQ. In contrast, note that the use of network coding can achieve the same without such feedback, in exchange for decoding overhead.A key issue to be resolved in making a comparison between routing and coding would be how critical feedback signaling is, for the throughput of routing policies. With this motivation, we first explore how feedback at a given node affects its throughput, with arbitrary rates of its one-hop neighbors to the destination. Static routing policies which are essentially feedback independent, are considered. An explicit characterization of the optimal policies under such a feedback constraint is obtained, which turns out to be a natural generalization of both flooding and traditional routing (which does not exploit local broadcast, because the next hop is fixed prior to the transmission). When losses at the receivers are independent (still allowing for dependencies on transmissions by two different nodes, to model interference), the reduction in capacity due to constraining the feedback is limited to a constant fraction (e−1=37%) of the coding capacity, and gets arbitrarily close to optimal as the unconstrained capacity goes to zero. We also extend this analysis to a layered multihop network and also compare the throughput of flooding to backpressure via simulations for a layered network assuming independent losses. Finally, if there are dependencies in the losses seen by receivers from a single broadcast, the reduction could be arbitrarily bad, even with just two hops.

Local Broadcast Algorithms in Wireless Ad Hoc Networks: Reducing the Number of Transmissions

There are two main approaches, static and dynamic, to broadcast algorithms in wireless ad hoc networks. In the static approach, local algorithms determine the status (forwarding/nonforwarding) of each node proactively based on local topology information and a globally known priority function. In this paper, we first show that local broadcast algorithms based on the static approach cannot achieve a good approximation factor to the optimum solution (an NP-hard problem). However, we show that a constant approximation factor is achievable if (relative) position information is available. In the dynamic approach, local algorithms determine the status of each node "on-the-fly” based on local topology information and broadcast state information. Using the dynamic approach, it was recently shown that local broadcast algorithms can achieve a constant approximation factor to the optimum solution when (approximate) position information is available. However, using position information can simplify the problem. Also, in some applications it may not be practical to have position information. Therefore, we wish to know whether local broadcast algorithms based on the dynamic approach can achieve a constant approximation factor without using position information. We answer this question in the positive-we design a local broadcast algorithm in which the status of each node is decided "on-the-fly” and prove that the algorithm can achieve both full delivery and a constant approximation to the optimum solution.