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The mobile user objective system (MUOS) is a geo-satellite communications system derived from the terrestrial cellular WCDMA air interface. WCDMA power control with the long geo-satellite round trip time presents substantial challenges. This paper describes the Point-to-Point power control system with simulation results using time-varying channel models specified by the MUOS program office.
The performance of a serially concatenated convolutional code (SCCC) for frequency hopped M-ary phase shift keying communication systems over an additive white Gaussian channel noise (AWGN) in the presence of a partial-band noise jammer is discussed in the paper. The scaling of the log-likelihood ratio (LLR) which improves the SNR dynamic range and the jamming strategy are also discussed in the paper...
If binary signaling is used in an n-channel OFDM link, the maximum possible bit rate is n bits per OFDM symbol duration. We show a simple scheme based on selective channel use that increases this capacity by nearly 60%. By using only k channels out of the n, we show how to use the choice of the k channels as an additional auxiliary channel. For proper choice of parameters, the information transferred...
Communications systems are increasingly reliant on system-on-chip (SoC) solutions. As the complexity and size of SoCs continues to grow, so does the risk of ??Trojan?? attacks, in which an integrated circuit (IC) design is surreptitiously and maliciously altered at some point during the design or manufacturing process. Despite the risks that such an attack entail, relatively little attention has been...
The Link-16 is the tactical data link utilized by the Joint Tactical Information Distribution System (JTIDS). The JTIDS system is important due to its wide use by U.S. armed forces, NATO, and other allied militaries. Link-16 is a hybrid frequency-hopped/direct sequence spread spectrum system that utilizes minimum-shift keying (MSK) to modulate the chips, cyclical code-shift keying (CCSK) to modulate...
The robustness to jamming signal is an important property for military communication systems. Some previous work has shown that the frequency domain code division multiplexing (CDM) efficiently rejects the interference. In general, however, the jamming signal has higher power than ordinary interference which leads to insufficient jamming rejection performance of these schemes. To mitigate this insufficiency,...
Existing cooperative communications protocols are designed with the assumption that users always behave in a socially efficient manner. This assumption may be valid in networks under the control of a single authority where nodes cooperate efficiently to achieve a common goal. On the other hand, in commercial wireless networks where nodes are individually motivated to cooperate, the assumption that...
In this paper, we discuss a novel priority assignment and packetization scheme to transport H.264/AVC video packets over wireless networks. Specifically, we discuss a comprehensive packet priority assignment scheme for unequal error protection, followed by the use of adaptive network abstraction layer unit (NALU) sizes and NALU fragmentation schemes. These schemes use the standard-compliant decoder...
A framework for multiple access protocols supporting the admission and sustenance of concurrent transmissions in Gaussian interference channels (G-IC) encountered in opportunistic unstructured networks or unused spectral bands under quasi-static fading is proposed. Each node is assumed to be equipped with successive decoding capabilities and seeks admission to the network by requesting a minimum rate,...
Reed Solomon (RS) forward error correction (FEC) coding in conjunction with M-ary hyper phase-shift keying (MHPSK) and soft decision decoding is considered in order to improve the robustness of a high spectral efficiency, non-linear satellite communications link. In this paper, a system that utilizes RS encoding of the information symbols which are then transmitted with MHPSK is evaluated in terms...
We develop accurate and robust one-dimensional EXIT chart methods to design raptor codes with binary and higher-order modulations on AWGN channels over any desired range of SNRs. We formulate the check-node degree distribution optimization as a linear program that optimizes a suitable objective function of the desired operating points. The throughput curves predicted by the analysis are easily compared...
In our previous work, we have shown that hybrid ARQ (HARQ) can be used to achieve secret communication over a fast fading channel. This is a physical-layer technique that can be used in conjunction with conventional cryptography to provide further protection from an eavesdropper. The key to our previous work was to use reliability-based HARQ to improve the decoder performance at the desired user much...
A novel decoder covariance optimization approach is proposed for jointly designing the minimum mean square error (MMSE) transceivers of downlink multicell multiuser multiple-input-multiple-output (MIMO) systems subject to general linear power constraints. Per-antenna power constraint (single cell or multicell), total power constraint (single cell) and per-cell power constraint (multicell) are presented...
The opportunistic large array (OLA) with transmission threshold (OLA-T) is a simple form of cooperative transmission that limits node participation in broadcasts. Performance of OLA-T has been studied for disc-shaped networks. This paper analyzes OLA-T for strip-shaped networks. The results also apply to arbitrarily shaped networks that have previously limited node participation to a strip. The analytical...
In this paper, we construct rate compatible low density parity-check (RC-LDPC) codes from a new perspective. In traditional methods, the columns of parity-check matrix, each of which corresponds to a bit of a codeword, are deleted or added to obtain codes at various rates. Different from them, only the rows of parity-check matrix are operated in our method. Since the number of columns remains unchanged,...
Scintillation mitigation is an important aspect of free-space optical (FSO) communications link design. While a number of hardware-based mitigation techniques have been proposed in the literature and deployed in experimental systems (e.g., aperture averaging, wavelength diversity, etc.), novel baseband signal processing approaches have the potential to complement - or even supplant - these traditional...
We present a systematic network coding strategy for cooperative communication, in which some nodes may replicate-and-forward packets in addition to sending random linear combinations of the packets. We argue that if this strategy is used only at certain nodes in the network, the throughput will not be reduced relative to random linear network coding. Furthermore, if packets can traverse the entire...
Cognitive radio (CR) is a revolutionary wireless mobile communication technology. Smart users can use the CR technology to sense the surrounding environment, search for available spectrum resources and access spectrum dynamically. Differential frequency hopping (DFH) is known as an effective FH technique for increasing data rate of HF communication system. In this study, the cognitive radio technology...
A typical military airborne networking scenario involves small groups of relatively closely-spaced aircraft which fly as a unit to perform a common mission. These aircraft need to maintain very long data links with other aircraft in the presence of strong interference from hostile jammers. Due to the physical separation of the aircraft, the time difference of arrival can often be greater than the...
In network communication, Byzantine attacks, i.e., attacks in consequence of the packet dropping and cheating (modified packets), are usually difficult to guard against. Several multi-path packet routing schemes have been recently proposed to recover lost packets on account of the packet dropping (caused by path failures or attacks), but no effective solutions have been proposed to counter cheating...
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