MPEG-DASH in combination with CENC (Common Encryption), builds a solid foundation for interoperable media streaming on the Web. With W3C HTML5 premium media extensions MSE (Media Source Extensions) and EME (Encrypted Media Extension), being available in all major browsers today, a wide range of supported platforms exists already. A Content Decryption Module (CDM) is required for a functional EME implementation. We introduce an open source implementation of a CDM and explain the architecture behind this solution. It is designed to work with multiple DRM systems in an open and standardized way. To improve interoperability for protected content across the whole playback chain, the CDMi specification adds another abstraction layer between CDM and DRM system. We show that an open source CDM also integrates with the CDMi approach to support hardware-based DRM platforms.

The simulation of remote sensing images is a valuable tool for defining future Earth observation systems, optimizing instrument parameters, and developing and validating data-processing algorithms. A scene simulator for optical Earth observation data has been developed within the Environmental Mapping and Analysis Program (EnMAP) hyperspectral mission. It produces EnMAP-like data following a sequential processing approach consisting of five independent modules referred to as reflectance, atmospheric, spatial, spectral, and radiometric modules. From a modeling viewpoint, the spatial module is the most complex. The spatial simulation process considers the satellite-target geometry, which is adapted to the EnMAP orbit and operating characteristics, the instrument spatial response, and the sources of spatial nonuniformity (keystone, telescope distortion and smile, and detector coregistration). The spatial module of the EnMAP scene simulator is presented in this paper. The EnMAP spatial and geometric characteristics will be described, the simulation methodology will be presented in detail, and the capability of the EnMAP simulator will be shown by illustrative examples.

This paper proposes data rate adaptation based on code division multiplexing (CDM). Under investigation are OFDM systems with cyclic delay diversity (CDD) and with spatial phase coding (SPC). These schemes are promising candidates for future broadband wireless systems. As lower bound, maximum ratio transmission (MRT) is chosen as reference. Imperfections due to channel estimation are taken into account in the investigations. The comparison of adaptive CDM versus adaptive coding shows that adaptive CDM outperforms adaptive coding, especially when spatial transmit diversity schemes are applied. This result is of interest for the design of future broadband adaptive transmission systems like IMT-Advanced.

Code division multiplexing (CDM) is an efficient coding scheme without rate loss. The combination of robust and spectrally efficient orthogonal frequency division multiplexing (OFDM) with CDM results in an orthogonal frequency code division multiplexing (OFCDM) scheme. This paper investigates the potential of OFCDM for future broadband mobile radio schemes such as IMT-Advanced. The focus is on the performance analysis and comparison of OFDM and OFCDM. The investigations take into account channel coding and different spatial diversity and pre-coding schemes like cyclic delay diversity (CDD), spatial phase coding (SPC) and maximum ratio transmission (MRT). The results show that OFCDM outperforms OFDM with respect to bit error rate performance.

In this paper a spatial phase coding (SPC) scheme is investigated for its application in OFDM systems. With SPC the phase relation of the signals between multiple transmit antennas is modified such that the probability of constructive superposition of the signals at the receiver antenna is increased. The principle is based on selective phase flipping. The promising feature of this scheme is that only the superimposed channel has to be estimated at the receiver and not all channels from the different transmit antennas. Moreover, it requires a very small amount of feedback information for pre-coding compared to existing solutions. The performance of SPC is compared to that of spatial diversity and pre-coding schemes like phase flip diversity (PFD), cyclic delay diversity (CDD) and maximum ratio transmission (MRT) for typical indoor as well as outdoor environments.

In this paper the effects of channel estimation errors on spatial pre-coding schemes are analyzed. Under investigation is a novel pre-coding scheme with phase flipping, referred to as spatial phase coding (SPQ. The sensitivity of SPC to channel estimation errors in an OFDM system is compared to that of maximum ratio transmission (MRT), equal gain transmission (EGT) and transmit antenna selection diversity (SD). These diversity and pre-coding schemes have different requirements on the channel estimation and the feedback. Results are presented for a broadband OFDM system with two-dimensional pilot-symbol-aided channel estimation in a typical frequency- and time-selective propagation environment. It is shown that SPC is more robust to channel estimation errors than other spatial pre-coding schemes.

The performance of spatial pre-coding schemes depends on the amount of channel state information available at the transmitter. A novel approach is spatial pre-coding with phase flipping investigated in this paper. The scheme is referred to as spatial phase coding (SPQ). Two flipping criteria, the angle criterion (AC) and the absolute value criterion (AVC), are proposed which change the phase relation of the signals between multiple transmit antennas such that the probability of constructive superposition of the signals at the receiver antenna is increased. Compared to known pre-coding schemes, SPC AVC does not need knowledge about the channel from each transmit antenna for pre-coding. Instead, it requires only information about the absolute value of the superimposed channel. This paper shows that SPC can achieve an array gain additional to the diversity gain. This is not possible with schemes like transmitter antenna selection diversity (SD). The lower bounds for SPC are defined by equal gain transmission (EGT) and maximum ration transmission (MRT).

The paper investigates different diversity concepts for OFDM systems. These are space frequency block codes (SFBCs) and code division multiplexing (CDM). The performances of both, and of combinations of both, are compared for coded OFDM systems in a Rayleigh fading channel. The applied SFBCs and CDM have in common that they have no rate loss and thus do not decrease the bandwidth efficiency of the system. While the SFBCs exploit space and frequency diversity, CDM exploits frequency and time diversity in OFDM systems. Additionally, the effects due to diversity gains by channel coding are taken into account in the investigations.

In this paper the trade-off between time diversity and the inter-carrier interference (ICI) in an OFDM based MC-CDMA system is discussed. Our approach is to partially shift each spectrum of an OFDM symbol at the transmitter by using different phase shifts in the time domain at different antennas after the OFDM modulation. The summary signal at the receiver has a wider Doppler spectrum as the result of different uncorrelated Rayleigh fading channels. This leads to an artificially increased selective time channel transfer function, which is more favorable for the channel decoder at the receiver. The trade-off between Doppler diversity and ICI is found at about 9% maximum Doppler spread of the subcarrier distance for flat fading channels and frequency selective fading channel models. The distance to the independent Rayleigh channel bound by applying an MMSE detector is less than 2 dB for convolutional coding and about 2 dB for turbo coding at a BER of 10/sup -3/ for flat fading channels. For frequency selective fading channels this approaches to less than 1 dB to the independent Rayleigh channel bound.

The possibility of combining differential demodulators in time direction and frequency direction for orthogonal frequency-division multiplexing (OFDM) frames is investigated. The proposed algorithm uses not only the direction in which the information is modulated, but also joins it with other symbols in time or frequency direction of the OFDM frame, resulting in an additional second direction that is differentially demodulated as well. In the special case that is investigated here, the second direction does not carry any modulated information. Nevertheless, it is shown that it can be used for the two-dimensional demodulation process without changing the transmitter. Therefore, the proposed algorithm is applicable for existing digital transmission systems, for example, digital audio broadcasting, as well as new systems.

We investigate broadband OFDM systems which apply beamforming in combination with different space-time diversity techniques. Various beamforming scenarios with transmitter and/or receiver sided beamforming are considered. Space-time diversity is obtained by cyclic delay diversity (CDD) in order to artificially shape the spectrum of the received signal. Thus, an advantageous distribution of the errors before a Viterbi channel decoder is obtained. Simulation results for the bit error rate performance are presented and compared for OFDM systems applying different beamforming scenarios and CDD in a Rayleigh fading channel. Maximum ratio combining (MRC) of the signals received on multiple beams/antennas is also taken into account in the performance analysis.

In this paper, orthogonal frequency-division multiplexing-code-division multiplexing (OFDM-CDM) is presented and investigated as alternative to conventional OFDM for high rate data transmission. An additional multipath diversity gain can be obtained with OFDM-CDM by spreading each data symbol in frequency and time. The optimum reliability information for the Viterbi (1979) decoder is derived for OFDM-CDM systems, and the tradeoff between spreading and channel coding in OFDM systems is presented. By using efficient interference cancellation or joint detection techniques, it can be shown that OFDM-CDM outperforms conventional OFDM with respect to bit error rate (BER) performance and bandwidth efficiency.

In this paper, we investigate different antenna diversity concepts, which can be easily applied to orthogonal frequency division multiplexing (OFDM) systems. The focus is to provide diversity schemes, which can be implemented to already existing OFDM systems without changing the standards. It is also possible to combine these techniques in a suitable manner. The introduced diversity techniques are applied to the DVB-T system for error performance investigations, which were done by simulation.

An OFDM-CDM (orthogonal frequency division multiplexing code division multiplexing) system with adaptive symbol mapping is presented. This combination enables a robust transmission with flexible error protection and data rate adaptation for parallel data streams by exploiting additional diversity due to CDM. Performance results are presented for fading channels where OFDM-CDM with adaptive symbol mapping and soft interference cancellation is compared to conventional OFDM systems also taking into account channel coding with variable code rates.

The possibility of combining differential demodulators in time direction and frequency direction for orthogonal frequency division multiplexing (OFDM) frames is investigated. The proposed algorithm uses not only the direction in which the information is modulated, but also joins it with the additional second direction that is differentially demodulated as well. In the special case that is investigated here, the second direction does not carry any modulated information, but can be used for the two-dimensional demodulation process without changing the transmitter. Therefore, the proposed algorithm is applicable for existing digital transmission systems, like for example digital audio broadcasting (DAB), as well as new systems.

In this paper, we investigate different spatial transmit diversity concepts for orthogonal frequency division multiplexing (OFDM) systems. The idea is to artificially increase the frequency and time selectivity of the resulting channel transfer function at the receiver antenna by specific time-variant phase rotations of the signal at the transmit antennas. The achievable performance gains with the proposed transmit diversity concepts are presented for convolutionally coded OFDM systems in typical indoor and outdoor environments. The new concepts can be implemented in already standardized and existing OFDM systems like DAB and DVB-T or HIPERLAN/2, IEEE 802.11 and MMAC, without changing the standards and the receivers. Moreover, we show further performance improvements by combining the spatial transmit diversity concepts for OFDM with code division multiplexing (CDM).

We investigate the potential of code division multiplexing (CDM) and transmit antenna diversity in coded orthogonal frequency division multiplexing (OFDM) systems. The CDM component applied to OFDM systems can additionally exploit diversity in frequency and time selective mobile radio channels. For coded OFDM and OFDM-CDM systems we propose an antenna concept based on transmit diversity achieved by shifting the phase of the signal on the individual antennas. We show the design of such an antenna diversity concept and present the performance improvements due to CDM and transmit antenna diversity in coded OFDM systems for typical indoor and outdoor multipath channels.

We analyze the influence of the effects of the non-linearity due to high power amplifiers in MC-CDMA scheme using BPSK modulation. The results are compared to those obtained with the classical BPSK modulated DS-CDMA scheme. It is shown that without predistortion the total degradation for the up-link of a cellular mobile communications system is about 2 dB more for the MC-CDMA system compared to the DS-CDMA system. However, for the down-link case (assuming a full system load) the MC-CDMA system outperforms by about 1.5 dB the DS-CDMA system. In addition, the performance of an analytical predistortion technique is evaluated. The results with predistortion showed that for the up-link of a MC-CDMA system one can achieve about 1.8 dB gain. Similar gains for the down-link case are also obtained. Hence, with predistortion, the HPA non-linearities may have the same influence on the performance of the up-link of both systems, i.e. MC-CDMA and DS-CDMA systems.

The potential of pilot-symbol-aided channel estimation in two dimensions are explored. In order to procure this goal, the discrete shift-variant 2-D Wiener filter is derived and analyzed given an arbitrary sampling grid, an arbitrary (but possibly optimized) selection of observations, and the possibility of model mismatch. Filtering in two dimensions is revealed to outperform filtering in just one dimension with respect to overhead and mean-square error performance. However, two cascaded orthogonal 1-D filters are simpler to implement and shown to be virtually as good as true 2-D filters.

This paper presents a novel multiple access scheme designed for mobile multi-media applications. The scheme is referred to as spread-spectrum multi-carrier multiple-access (SS-MC-MA) and exploits the advantages given by the combination of the spread-spectrum technique with multi-carrier modulation, known from multi-carrier code division multiple access (MC-CDMA) schemes. In contrast to MC-CDMA, the SS-MC-MA separates the users' signals according to an FDMA scheme on the sub-carrier level. Thus, the novel scheme avoids multiple access interference (MAI) within a cell. SS-MC-MA can use the same radio interface for the up- and the down-link. Its bandwidth efficiency is comparable to the high bandwidth efficiency achievable with MC-CDMA in the down-link. By providing a high degree of flexibility, this system can be a good candidate for the future Universal Mobile Telecommunications Systems (UMTS).

Mobile radio systems with high power and bandwidth efficiency can be designed by the combination of code division multiple access (CDMA) and multi-carrier modulation. The problem of channel estimation in the downlink of a multi-carrier (MC)-CDMA system is investigated. We study pilot-symbol-aided channel estimation in two dimensions using two cascaded one-dimensional FIR filters, dimensioned as Wiener filters for the worst case channel conditions. The performance with real channel estimation is demonstrated for various mobile radio environments and velocities. Furthermore, we examine the accuracy of a simple approximation to evaluate the system performance with real channel estimation, where the analysis of the channel estimation is separated from the evaluation of the remaining mobile radio system.