Cyclic code-shift keying (CCSK) is the baseband symbol modulation scheme used by Joint Tactical Information Distribution System (JTIDS), the communication terminal of Link-16. Since CCSK is non-orthogonal, an analytic...
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Cyclic code-shift keying (CCSK) is the baseband symbol modulation scheme used by Joint Tactical Information Distribution System (JTIDS), the communication terminal of Link-16. Since CCSK is non-orthogonal, an analytic evaluation of its performance in terms of probability of symbol error is nontrivial. In this paper, an analytic upper bound on the probability of symbol error of CCSK is derived for the 32-chip CCSK sequence chosen for JTIDS. The probability of symbol error obtained with the analytic method is compared with that obtained by Monte Carlo simulation for additive white Gaussian noise. The results show that the analytic method yields a tight upper bound. In addition to the 32-chip CCSK sequence chosen for JTIDS, a new 32-chip CCSK sequence with a smaller maximum off-peak cross-correlation is obtained and evaluated both analytically and by Monte Carlo simulation. The results obtained for the new CCSK sequence compare favorably with the sequence chosen for JTIDS.
In 2008, the French MoD has started an experimental SATCOM network which aims at using EHF resources (44/21 GHz) in an efficient manner. It will lead to an operational use of this frequency band in order to cope with ...
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In 2008, the French MoD has started an experimental SATCOM network which aims at using EHF resources (44/21 GHz) in an efficient manner. It will lead to an operational use of this frequency band in order to cope with the lack of SHF frequency resources. Contrary to the SHF concept of use where links are planned with constant data rates and static margins, the EHF band requires the use of fading mitigation Techniques to adapt to transmission conditions. The EHF experiment consists of two networks: - the first one is based on DVB-S2/DVB-RCS (digital video broadcasting satellite 2)/(digital video broadcasting-return channel satellite) standards, the second one uses a frequency hopping electronic protected modem (EPM). The aim of the experiment is to: assess solutions based on COTS (components on the shelf (DVB-S2/DVB-RCS) and EPM test and define EHF terminals, define and to test services offer in EHF.
This paper presents a hybrid image compression scheme based on a block based compression algorithm referred to as Vector Quantization (VQ) combined with the Differential Pulse Code modulation (DPCM) technique. The pro...
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This paper presents a hybrid image compression scheme based on a block based compression algorithm referred to as Vector Quantization (VQ) combined with the Differential Pulse Code modulation (DPCM) technique. The proposed image compression technique called the PVQ scheme results in enhanced image quality as compared to the standalone VQ. The generated codebooks for the PVQ scheme are more robust for image coding than that of the VQ. This made our system a suitable candidate for developing on chip image sensor with integrated data compression processor. The proposed system was validated through FPGA implementation. The resulting implementation achieved good compression and image quality with moderate system complexity.
Capacity dimensioning is one of the key procedures in wireless network planning. In this paper, the question of how to efficiently evaluate the capacity of wireless communications systems with a comprehensive consider...
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Capacity dimensioning is one of the key procedures in wireless network planning. In this paper, the question of how to efficiently evaluate the capacity of wireless communications systems with a comprehensive consideration of adaptive modulation and coding (AMC), hybrid automatic repeat request (HARQ) and packet multimedia traffic source is examined. By investigating the joint effect of AMC and HARQ and modeling the packet multimedia traffic source as a discrete Markov modulated Poisson process (D-MMPP), a four-dimensional discrete time Markov chain (DTMC) is proposed to analyze the system behavior. Based on the stationary state distribution of this Markov chain, system capacity in terms of throughput, delay and packet loss rate is derived in closed-form expressions. Capacity dimensioning results are presented to illustrate the interdependence between system performance and system parameters. Computer simulations are also carried out to verify these results.
This paper analyzes a two-hop extension to the coverage of an IEEE 802.16 cell. There is natural degradation in cell capacity due to multihop communications which can be mitigated by spatial reuse, adaptive modulation...
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This paper analyzes a two-hop extension to the coverage of an IEEE 802.16 cell. There is natural degradation in cell capacity due to multihop communications which can be mitigated by spatial reuse, adaptive modulation and coding. We estimate the available capacity by analyzing the random geometry related to the locations of the base station, the sponsor nodes and the mesh subscriber stations situated two hops away from the base station. The results show the trade-offs of extending the coverage area and the decrease of the capacity.
Considering the multiple input and multiple output (MIMO) communication systems under both cases of limited and unlimited power per transmitted antenna, the paper proposes an algorithm of optimal transmit power, refer...
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Considering the multiple input and multiple output (MIMO) communication systems under both cases of limited and unlimited power per transmitted antenna, the paper proposes an algorithm of optimal transmit power, referred to as water-filling algorithm. The principle of power allocation under limited power systems and no limited power ones are discussed, respectively. The principle of power water-filling for the limited-power systems is introduced and examples also are provided. Following, the paper considers the performance of multiple transmit and single receive antenna (MISO) system employing orthogonal space-time block coding (STBC) and binary phase shift-keying (BPSK) modulation, and derives a Chernoff upper bound (CUB) theoretical expression of bit error rate (BER) for the multiple transmit antennas selection MISO systems. The numerical results show that appropriate power allocation for transmit antennas selected can effectively enhance system bit error performance. Meanwhile, the performance improvement is not obvious if total transmit power is filled to the best antenna selected. These conclusions have a guidance function in practical mobile communication systems.
In this paper, we present the code design structure of unitary and non-unitary differential space-frequency group codes (DSFCs) for multiple-input multiple-output (MIMO)- orthogonal frequency division multiplexing (OF...
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In this paper, we present the code design structure of unitary and non-unitary differential space-frequency group codes (DSFCs) for multiple-input multiple-output (MIMO)- orthogonal frequency division multiplexing (OFDM) systems based on optimal coherent space-frequency (SF) group codes. Under the assumption that the transmitter knows only the delay profile of the channel, a differential transmission rule incorporated with subcarrier allocation is obtained that allows data to be sent without channel estimates at the transmitter or receiver. The differential encoding/decoding is performed in the frequency domain within each single OFDM symbol. Therefore, proposed DSFCs can be successfully decoded even for a rapidly fading channel which may change independently from one OFDM symbol to another. Unitary and nonunitary DSFCs, that are constructed based on design criteria, are compared with recently published techniques in the literature and shown to inherit coding gain of optimal coherent SF codes. Due to design structure and energy constraints, our nonunitary DSFCs do not blow up or diminish during the differential encoding.
Ambiguity function method is used to study the ranging and Doppler tolerance performance of CW signal based on pseudo-random code bi-phase modulation (PRCBPM). Its ranging resolution and Doppler tolerance confine are ...
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Ambiguity function method is used to study the ranging and Doppler tolerance performance of CW signal based on pseudo-random code bi-phase modulation (PRCBPM). Its ranging resolution and Doppler tolerance confine are calculated, the ranging performance and Doppler tolerance capability are simulated by using the software of Matlab and the influence factors are analyzed. The simulation results are consistent with the calculation values. The results show that the ranging precision of PRCBPM signal depends on the code width and is more improved with the narrower code width, and that the Doppler tolerance performance lies on and is inverse proportion to the product of code width and code length.
With significant research being conducted in Ultra Wideband communications to increase error performance, this paper proposes a combination of user multiplexing and data encoding to achieve a BER improvement. Through ...
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With significant research being conducted in Ultra Wideband communications to increase error performance, this paper proposes a combination of user multiplexing and data encoding to achieve a BER improvement. Through the use of non-binary turbo coding, data is modulated to form a time hopping code which is applied to a time-reversed UWB system. Comparative results with conventional binary coding are given, showing the possibility for BER improvements in systems with a low number of users. Slight performance degradations for a large number of users exist. The effects of a user applying turbo coding on other users not applying forward error correction is also studied.
We consider synchronization techniques required to enhance the cellular network capacity using base station cooperation. In the physical layer, local oscillators are disciplined by the global positioning system (GPS) ...
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We consider synchronization techniques required to enhance the cellular network capacity using base station cooperation. In the physical layer, local oscillators are disciplined by the global positioning system (GPS) and over the backbone network for outdoor and indoor base stations, respectively. In the medium access control (MAC) layer, the data flow can be synchronized by two approaches. The first approach uses so-called time stamps. The data flow through the user plane and through copies of it in each cooperative base station is synchronized using a timing protocol on the interconnects between the base stations. The second approach adds mapping information to the data after the user plane processing is almost finalized. Each forward-error encoded transport block, its modulation and coding scheme and the resources where it will be transmitted are multicast over the interconnect network. Interconnect latency is reduced below 1 ms to enable coherent interference reduction for mobile radio channels.
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