This dissertation poses that the digital transition is best understood as simultaneously a technological and cultural phenomena. As a physical change in the means of distribution, transmission, and reception of media content, the digital transition is an important factor in changing technological, aesthetic, and legal norms. As a cultural form, the digital is positioned as a moderator between continuity and discontinuity. Through a reading strategy inspired by Walter Benjamin this dissertation reads the physical and cultural implications of the digital transition in television in the United States through political categories. The chapters are case studies in the adoption of digital televisions for home use, digital television production technologies, digital transmission technologies, and digital distribution systems. Each case study examines the tenuous production of publics in the context of the dialectical pressures of the digital. By taking this approach I intend to contribute to the rhetorical dimension of television studies, the digital turn in rhetorical and public sphere studies, and the legal and aesthetic dimensions of production studies. The dialectical approach to the digital allows the study of television to theorize the trajectory of emerging media and the political implications of that movement.

Utah State University began to present radio programs on a regular basis over KSL Radio in Salt Lake City in 1931. In 1952, its first television program was televised over KSL-TV. Today the University is broadcasting programs over the majority of Utah's radio and television stations. This thesis covers the development of broadcasting from USU in three major areas: (1) radio and television programs presented over Utah broadcasting outlets, (2) the construction of radio and television stations on the campus, and (3) instruction in broadcasting. There has been no attempt made to evaluate the University's use of these media. It is pointed out that off-campus broadcasting did not expand in an organized manner; that the later attempt to coordinate it has not achieved complete success, and that broadcast training at Utah State University paralleled the development of the television industry in Utah. Also pointed out is the role that students played in establishing the Institution's first broadcasting facility.

<p>Media such as movies and images are nowadays produced and distributed digitally. It is usually simple to make copies of digital content. Consequently illegal pirate copies can be duplicated and distributed in large quantities. One way to deter authorized content receivers from illegally redistributing the media is watermarking. If individual watermarks are contained in the digital media and a receiver is a pirate and redistributes it, the pirate at the same time distributes his identity. Thus a located pirate copy can be traced back to the pirate. The watermarked media should otherwise be indistinguishable from the original media content.</p><p>To distribute media content scalable transmission methods such as broadcast and multicast should be used. This way the distributor will only need to transmit the media once to reach all his authorized receivers. But since the same content is distributed to all receivers the requirement of individual watermarks seems to be contradictory.</p><p>In this thesis we will show how individually watermarked media content can be transmitted in a scalable way. Known methods will be reviewed and a new method will be presented. The new method is independent of what type of distribution that is used. A system with robust watermarks that are difficult to remove is described. Only small parts of the media content will be needed to identify the pirates. The method will only give a small data expansion compared to distribution of non-watermarked media.</p><p>We will also show how information theory tools can be used to expand the amount of data in the watermarks given a specific size of the media used for the watermarking. These tools can also be used to identify parts of the watermark that have been changed by deliberate deterioration of the watermarked media, made by pirates.</p> / Report code: LiU-Tek-Lic-2005:67.

<p>The need for broadcast encryption arises when a sender wishes to securely distribute messages to varying subsets of receivers, using a broadcast channel, for instance in a pay-TV scenario. This is done by selecting subsets of users and giving all users in the same subset a common decryption key. The subsets will in general be overlapping so that each user belongs to many subsets and has several different decryption keys. When the sender wants to send a message to some users, the message is encrypted using keys that those users have. In this thesis we describe some broadcast encryption schemes that have been proposed in the literature. We focus on stateless schemes which do not require receivers to update their decryption keys after the initial keys have been received; particularly we concentrate on the Subset Difference (SD) scheme.</p><p>We consider the effects that the logical placement of the receivers in the tree structure used by the SD scheme has on the number of required transmissions for each message. Bounds for the number of required transmissions are derived based on the adjacency of receivers in the tree structure. The tree structure itself is also studied, also resulting in bounds on the number of required transmissions based on the placement of the users in the tree structure.</p><p>By allowing a slight discrepancy between the set of receivers that the sender intends to send to and the set of receivers that actually can decrypt the message, we can reduce the cost in number of transmissions per message. We use the concept of distortion to quantify the discrepancy and develop three simple algorithms to illustrate how the cost and distortion are related.</p> / Report code: LIU-Tek-Lic-2005:70.

Recently, many multi-receiver identity-based encryption schemes have been proposed in the literature. However, none can protect the privacy of message receivers among these schemes. In this thesis, we present an anonymous multi-receiver identity-based encryption scheme where we adopt Lagrange interpolating polynomial mechanisms to cope with the above problem. Our scheme makes it impossible for an attacker or any other message receiver to derive the identity of a message receiver such that the privacy of every receiver can be guaranteed. Furthermore, the proposed scheme is quite receiver efficient since each of the receivers merely needs to perform constant times (twice in fact) of pairing computation, which is the most time-consuming computation in pairing-based cryptosystems, to decrypt the received message. Furthermore, we prove that our scheme is secure against adaptive chosen plaintext attacks and adaptive chosen ciphertext attacks. Finally, we also prove that the receivers of the scheme can be anonymous.

Multi-user wireless systems with multiple antennas can drastically increase the capac- ity while maintaining the quality of service requirements. The best performance of these systems is obtained at the presence of instantaneous channel knowledge. Since uplink-downlink channel reciprocity does not hold in frequency division duplex and broadband time division duplex systems, efficient channel quantization becomes important. This thesis focuses on different quantization techniques in a linearly precoded multi-user wireless system. Our work provides three major contributions. First, we come up with an end-to-end transceiver design, incorporating precoder, receive combining and feedback policy, that works well at low feedback overhead. Second, we provide optimal bit allocation across the gain and shape of a complex vector to reduce the quantization error and investigate its effect in the multiuser wireless system. Third, we design an adaptive differential quantizer that reduces feedback overhead by utilizing temporal correlation of the channels in a time varying scenario.

Multi-user wireless systems with multiple antennas can drastically increase the capac- ity while maintaining the quality of service requirements. The best performance of these systems is obtained at the presence of instantaneous channel knowledge. Since uplink-downlink channel reciprocity does not hold in frequency division duplex and broadband time division duplex systems, efficient channel quantization becomes important. This thesis focuses on different quantization techniques in a linearly precoded multi-user wireless system. Our work provides three major contributions. First, we come up with an end-to-end transceiver design, incorporating precoder, receive combining and feedback policy, that works well at low feedback overhead. Second, we provide optimal bit allocation across the gain and shape of a complex vector to reduce the quantization error and investigate its effect in the multiuser wireless system. Third, we design an adaptive differential quantizer that reduces feedback overhead by utilizing temporal correlation of the channels in a time varying scenario.

Previous research has developed a number of efficient protocols for streaming popular multimedia files on-demand to potentially large numbers of concurrent clients. These protocols can achieve server bandwidth usage that grows much slower than linearly with the file request rate, and with the inverse of client start-up delay. This hesis makes the following three main contributions to the design and performance evaluation of such protocols. The first contribution is an investigation of the network bandwidth requirements for scalable on-demand streaming. The results suggest that the minimum required network bandwidth for scalable on-demand streaming typically scales as K/ln(K) as the number of client sites K increases for fixed request rate per client site, and as ln(N/(ND+1)) as the total file request rate N increases or client start-up delay D decreases, for a fixed number of sites. Multicast delivery trees configured to minimize network bandwidth usage rather than latency are found to only modestly reduce the minimum required network bandwidth. Furthermore, it is possible to achieve close to the minimum possible network and server bandwidth usage simultaneously with practical scalable delivery protocols. Second, the thesis addresses the problem of scalable on-demand streaming of a more complex type of media than is typically considered, namely variable bit rate (VBR) media. A lower bound on the minimum required server bandwidth for scalable on-demand streaming of VBR media is derived. The lower bound analysis motivates the design of a new immediate service protocol termed VBR bandwidth skimming (VBRBS) that uses constant bit rate streaming, when sufficient client storage space is available, yet fruitfully exploits the knowledge of a VBR profile. Finally, the thesis proposes non-linear media containing parallel sequences of data frames, among which clients can dynamically select at designated branch points, and investigates the design and performance issues in scalable on-demand streaming of such media. Lower bounds on the minimum required server bandwidth for various non-linear media scalable on-demand streaming approaches are derived, practical non-linear media scalable delivery protocols are developed, and, as a proof-of-concept, a simple scalable delivery protocol is implemented in a non-linear media streaming prototype system.

The performance of multiple input single output (MISO) broadcast channels is strongly dependent on the availability of channel side information (CSI) at the transmitter. In many practical systems, CSI may be available to the transmitter only in a corrupted and incomplete form. It is natural to assume that the flaws in the CSI are random and can be represented by a probability distribution over the channel. This work is concerned with two key issues concerning MISO broadcast systems with random CSI: performance analysis and system design. First, the impact of noisy channel information on system performance is investigated. A simple model is formulated where the channel is Rayleigh fading, the CSI is corrupted by additive white Gaussian noise and a zero forcing precoder is formed by the noisy CSI. Detailed analysis of the ergodic rate and outage probability of the system is given. Particular attention is given to system behavior at asymptotically high SNR. Next, a method to construct precoders in a manner that accounts for the uncertainty in the channel information is developed. A framework is introduced that allows one to quantify the tradeoff between the risk (due to the CSI randomness) that is associated with a precoder and the resulting transmission rate. Using ideas from modern portfolio theory, the risk-rate problem is modified to a tractable mean-variance optimization problem. Thus, we give a method that allows one to efficiently find a good precoder in the risk-rate sense. The technique is quite general and applies to a wide range of CSI probability distributions.

Previous research has developed a number of efficient protocols for streaming popular multimedia files on-demand to potentially large numbers of concurrent clients. These protocols can achieve server bandwidth usage that grows much slower than linearly with the file request rate, and with the inverse of client start-up delay. This hesis makes the following three main contributions to the design and performance evaluation of such protocols. The first contribution is an investigation of the network bandwidth requirements for scalable on-demand streaming. The results suggest that the minimum required network bandwidth for scalable on-demand streaming typically scales as K/ln(K) as the number of client sites K increases for fixed request rate per client site, and as ln(N/(ND+1)) as the total file request rate N increases or client start-up delay D decreases, for a fixed number of sites. Multicast delivery trees configured to minimize network bandwidth usage rather than latency are found to only modestly reduce the minimum required network bandwidth. Furthermore, it is possible to achieve close to the minimum possible network and server bandwidth usage simultaneously with practical scalable delivery protocols. Second, the thesis addresses the problem of scalable on-demand streaming of a more complex type of media than is typically considered, namely variable bit rate (VBR) media. A lower bound on the minimum required server bandwidth for scalable on-demand streaming of VBR media is derived. The lower bound analysis motivates the design of a new immediate service protocol termed VBR bandwidth skimming (VBRBS) that uses constant bit rate streaming, when sufficient client storage space is available, yet fruitfully exploits the knowledge of a VBR profile. Finally, the thesis proposes non-linear media containing parallel sequences of data frames, among which clients can dynamically select at designated branch points, and investigates the design and performance issues in scalable on-demand streaming of such media. Lower bounds on the minimum required server bandwidth for various non-linear media scalable on-demand streaming approaches are derived, practical non-linear media scalable delivery protocols are developed, and, as a proof-of-concept, a simple scalable delivery protocol is implemented in a non-linear media streaming prototype system.