Adaptive Transmission Protocol Research Articles

Research on Adaptive Transmission Protocol of TT&C of Launch Vehicle Based on TDRSS

The application of TDRSS in TT&C of launch vehicle can improve the coverage and transmission rate of TT&C link. But the transmission protocol based on fixed transmission rate can not ensure the stable TT&C link based on TDRSS. The adaptive transmission protocol proposed in this paper can adjust the transmission rate according to the real-time transmission status during the whole flight. According to the different types of rocket-borne subscriber terminals, the open loop adaptive transmission protocol and closed loop adaptive transmission protocol are designed, which can both keep the stable transmission and improve the transmission efficiency.

SDATP: An SDN-Based Traffic-Adaptive and Service-Oriented Transmission Protocol

In this paper, a software-defined networking (SDN) based adaptive transmission protocol (SDATP) is proposed to support applications in fifth generation (5G) communication networks. For time-critical services, such as machine-type communication services for industrial automation, high reliability and low latency are required. To guarantee the strict service requirements, a slice-level customized protocol is developed with in-network intelligence, including in-path caching-based retransmission and in-network congestion control. To further reduce the delay for end-to-end (E2E) service delivery, we jointly optimize the placement of caching functions and packet caching probability, which reduces E2E delay by minimizing retransmission hops. Since the joint optimization problem is NP-hard, we transform the original problem to a simplified form and propose a low-complexity heuristic algorithm to solve the simplified problem. Numerical results are presented to validate the proposed probabilistic caching algorithm, including its adaptiveness to network dynamics and its effectiveness in reducing retransmission hops. Simulation results demonstrate the advantages of the proposed SDATP over the conventional transport layer protocol with respect to E2E packet delay.

FSO Cooperative System Analysis for DF based Relay

This paper presents performance and information theoretic analysis for cascaded free space optical (FSO) communication system using decode-and-forward relaying protocol. Optical links experience Gamma-Gamma distributed atmospheric turbulence, path loss, and misalignment losses. Derived closed-form statistical characteristics of the end-to-end SNR of the system are used for outage analysis, bit-error-rate analysis, and information theoretic analysis of the proposed system, for various modulation schemes and adaptive transmission protocols, respectively. In the performance analysis, impact of misalignment losses and scintillations is seen on various performance parameters and the adaptive modulation schemes using capacity of proposed systems.

MGF-based Analysis of Maximum Ratio Combining Receiver over Fisher-Snedecor Composite Fading Channel

Fisher Snedecor composite fading model is the combination of Nakagami-m and inverse Nakagami-m distribution. The Nakagami-m is used to characterize the small scale fading, whereas shadowing is modeled by inverse Nakagami-m distribution. In this paper, the closed-form expression for moment generating function (MGF) of instantaneous signal to noise ratio (SNR) over independent identically distributed (i.i.d) Fisher-Snedecor composite fading channel using maximum ratio combining (MRC) diversity technique is derived. By using newly derived MGF expression, we derive the closed-form expressions of average bit error rate (ABER) or average symbol error rate (ASER) for different binary and multilevel modulation schemes. The expressions for average channel capacity (ACC) under two adaptive transmission protocols like optimum rate adaption (ORA) and channel inversion with fixed rate (CIFR) are also derived using proposed MGF. Further, the numerical results of newly derived expression are presented and compared with the results of Rayleigh and Nakagami-m distribution which is the special case of Fisher Snedecor composite fading model.

Physical layer security with its applications in 5G networks: A review

5G network is expected to support massive user connections and exponentially increasing wireless services, which makes network security unprecedentedly important. Unlike traditional security-guaranteeing techniques which rely heavily on cryptographic approaches at upper layers of the protocol stack, physical-layer security (PLS) solutions fully take advantages of the characteristics of wireless channels to degrade the received signal qualities at the malicious users, and realize keyless secure transmission via signal design and signal processing techniques. PLS avoids the difficulties in the distribution and management of secret keys, and provides flexible security levels through adaptive transmission protocol design. Moreover, PLS techniques match the features of 5G networks well. Therefore, the application of PLS to 5G networks is a promising solution to address the security threats. This article presents a comprehensive review of the state-of-the-art PLS techniques, and discusses their applications in 5G networks. We first summarize the principle and advantages of PLS techniques, and point out the reasons why PLS is suitable for 5G networks. Then, we review the existing PLS methods in literature, and highlight several PLS solutions that are expected to be applied in 5G networks. Finally, we conclude this article and figure out some further research directions.

Capacity analysis of α − η − μ channels over different adaptive transmission protocols

In this study, the authors consider the α − η − μ fading channels and derive a new form for the cumulative distribution function of the signal-to-noise ratio (SNR) in terms of the bivariate Fox H-function. They also derive closed-form expressions for the moments and the amount of fading of the SNR. The capacity of α − η − μ fading channels is analysed assuming different adaptive transmission protocols. To this end, they provide analytical closed-form expressions for the average channel capacity with optimal rate adaptation (C ORA), optimal power and rate adaptation (C OPRA), channel inversion with fixed rate (CIFR) (C CIFR), and truncated CIFR (C TIFR). The derived expressions are valid for arbitrary values of the α, η, and μ fading parameters. The derived expressions can also be reduced to study the capacity of other fading distributions such as η − μ, α − μ, Weibull, and Nakagami. Numerical results are provided and compared with simulations to validate of the derived expressions.

Adaptive Transmission Protocols for Fountain-Coded Multicast in Packet Radio Networks

Fountain coding is a valuable tool for multicast transmissions in half-duplex packet radio networks if it is supported by an adaptive transmission protocol that compensates for fluctuations in the propagation losses on the radio links. Our goal is to devise low-complexity packet-by-packet adaptive modulation and channel coding protocols that provide high throughput for a broad range of multicast channels and operate with limited feedback and no knowledge of the fade levels or even the probability distribution for the fading on the radio links. The only control information for the protocols is derived from simple receiver statistics that are obtained by the demodulators and channel decoders in the receiving radios. Performance results are presented for practical fountain coding with low-complexity adaptive modulation and channel coding. Results on ideal fountain coding with adaptive transmission based on hypothetical perfect channel-state information are employed as performance benchmarks.

Novel Adaptive Transmission Protocol for Mobile Sensors that Improves Energy Efficiency and Removes the Limitation of State Based Adaptive Power Control Protocol (SAPC)

In this paper, we have presented a novel transmission protocol which is suited for battery-powered sensors that are worn by a patient when under medical treatment, and allow constant monitoring of health indices. These body-wearable sensors log data from the patient and transmit the data to a base-station or gateway, via a wireless link at specific intervals. The signal link quality varies because the distance between the patient and the gateway is not fixed. This may lead to packet drops that increase the energy consumption due to repeated retransmission. The proposed novel transmission power control protocol combines a state based adaptive power control (SAPC) algorithm and an intelligent adaptive drop-off algorithm, to track the changes in the link quality, in order to maintain an acceptable Packet success rate (PSR)(~99%). This removes the limitation of the SAPC by making the drop-off rate adaptive. Simulations were conducted to emulate a subject’s movement in different physical scenarios—an indoor office environment and an outdoor running track. The simulation results were validated through experiments in which the transmitter, together with the sensor mounted on the subject, and the subject themselves were made to move freely within the communicable range. Results showed that the proposed protocol performs at par with the best performing SAPC corresponding to a fixed drop-off rate value.

Energy Efficiency Comparison of a State Based Adaptive Transmission Protocol with Fixed Power Transmission for Mobile Wireless Sensors

In this paper a state-based adaptive power control protocol (SAPC) has been compared with classical fixed power communication for mobile wireless sensors. The distance between the transmitter and the base station is often not fixed as in the case of body wearable sensors. There can also be unaccounted obstructions in between the transmitter and the receiver. Since signal level attenuates with distance, it is important to choose the right power level that will not only deliver the packets with minimum error but conserve energy at the same time. The proposed adaptive algorithm does not transmit beacon or probe packet for channel quality estimation using the received signal strength before transmitting actual packets. It uses the present and past history of the outcome of packet transmission to evaluate and track link quality. The unique SAPC algorithm also controls the number of re-transmissions in each state. Experimental validation has been done using nRF24L01p transceiver modules. This algorithm can adapt itself to an unknown and variable radio channel in an energy-efficient manner. Experiments were conducted in indoor office environment within a university building and results show that SAPC uses up to 30% less energy than the fixed power communication

An Adaptive Video Streaming System Over a Cooperative Fleet of Vehicles Using the Mobile Bandwidth Aggregation Approach

With the development of vehicular networks, new types of networking services arise for automotive users. With regard to multimedia streaming services, a vehicle may not have good quality of service (QoS) of video streaming using its own individual 3G/3.5G wireless interface. This paper is motivated to investigate the $k$ - hop cooperative streaming scenario in fleet-based vehicular networks. When a vehicle requests a video stream encoded in H.264/Scalable Video Coding from the Internet using its 3G/3.5G network, it asks help from vehicles belonging to the same fleet within its $k$ - hop transmission range to download the requested video data cooperatively through these vehicles' 3G/3.5G network and then forward these downloaded video to the requested vehicle through vehicle-to-vehicle IEEE 802.11p networks. A $k$ - hop adaptive video transmission protocol is proposed to have better throughput by the following: 1) selecting suitable vehicles within $k$ - hop coverage to download video data and 2) retransmitting the lost video data from the video server to improve the quality of video. We utilize EstiNet Network Simulator and Emulator (NCTUns) to simulate the proposed schemes. Based on the simulation results, the priority-first (PF) assignment scheme with the PF retransmission scheme is suitable to be adopted in the cooperative video streaming scenario over the vehicular networks.

Applications of Capacity Limits to Performance Analyses of Adaptive Transmission Protocols for Packet Radios

Analytical methods are provided for use in performance evaluations, tradeoff studies, and preliminary designs of adaptive modulation and coding protocols that obtain their control information from practical sources. Our approach employs capacity limits and Markov chain models of fading to give analytical results on the throughput achieved by adaptive transmission in packet radio systems. The analytical methods replace simulations of the modem, iterative decoder, and time-varying fading channel. The amount of processor time required for protocol performance evaluations is decreased by several orders of magnitude.

An adaptive transmission protocol for exploiting diversity and multiplexing gains in wireless relaying networks

Abstract Wireless relaying networks with distributed space-time block codes have been shown to provide high link reliability. This is because of the space diversity gain from multiple transmitting relays, which improves by adding more relays. The drawback of this approach is the overall reduction in throughput of the network. In this paper, we propose a method to construct a distributed space-time block code that is combined with spatial modulation to find a flexible trade-off between reliability and throughput. This proposed method is not restricted to a specific number of relays and can be constructed as necessary. The constructed code also uses a novel adaptive transmission protocol to achieve higher space diversity, even with relays equipped with a single antenna. This protocol assumes use of coherent detection, meaning that a perfect channel estimation is available at the destination. Lastly, a new decoder is proposed that offers significant reduction in complexity to maintain high data throughput. All claims in this work are supported with theoretical analysis and backed up with empirical results.

基于云平台的医学影像可视交互平台

Traditional medical image visualization software is difficult to run in cross-platform without any coordination mechanism, while the capacity of storage and the volume rendering are limited. We propose a cloud-based medical image visualization platform. To use the large storage and the powerful graphics computing capabilities in the cloud, it can codec medical image and implement segmentation and visualize volume. Then we propose an adaptive medical meta-data and image data transmission protocol, which also supports collaborative visualization. Through real-time interaction between cloud and browsers and peer transmission between browsers and browsers, we achieve a variety of two-dimensional and three-dimensional visualization of images and collaborative interaction features. Experimental results show that our platform not only support browsing large amounts of two-dimensional data and pseudo-color mapping in real time, but also support advanced segmentation and three-dimensional visualization with coordination mechanism, and has better real-time interactivity.

Study of Adaptive Network Transmission Protocol in Mine

Combined with the transmission characteristics of multi node under master-slave mode, the paper design a high speed parallel transmission network based on RS485 bus, realize sampling nodes on the bus communication data packet detection using the ring buffer technique, and use the hardware timer and system parameters in the controller, combine with a custom packet to complete point to point protocol design of broadcast communication, in order to realize the free cutting of the whole system and reliable control and stable data transmission and node. The actual field test that communication rate has no error and error operation under the condition of the cable length of 2 Mbps and 100 m.

Adaptive Coding and Modulation for Multicast Transmission in Packet Radio Networks

A low-complexity protocol is described and evaluated for adaptation of the modulation and coding for multicast transmission in half-duplex packet radio networks. The adaptive multicast transmission protocol is designed to compensate for changes in propagation conditions that occur from packet to packet during a session with one sender and multiple receivers. The protocol relies on simple receiver statistics to obtain the control information for adapting the modulation and coding, and it also provides scheduling to avoid collisions among acknowledgments from the receivers. The throughput provided by the protocol is compared with performance results for hypothetical ideal adaptive multicast transmission protocols that are given perfect channel state information. We illustrate the importance of adaptive modulation and channel coding in systems that employ fountain coding for packet erasure correction.

Closed-form expressions for the average channel capacity of theα-μfading model under different adaptive transmission protocols

In this paper,we consider a small-scale multipath fading channel following the α- µ generalized fading model distribution.We first derive an expression for the amount of fading AF for this channel model to show the generalization attribute of this fading model recently reported in the literature. Then, we derive closed-form expressions for the average channel capacity considering this channel distribution under different adaptive transmission protocols, namely the simultaneous power and rate adaptation protocol, the optimal rate adaptation with fixed power protocol, and the channel inversion with fixed-rate protocol. All the obtained expressions are in closed-form and general expressions that can reduce to other channel capacity expressions that are well-known and to some others that are not known for Rayleigh, Nakagami-m, and Weibull, as special cases. The derived expressions in this paper are new and have not been previously reported in the literature. Copyright © 2012 John Wiley & Sons, Ltd.

An Energy-Efficient Adaptive Transmission Protocol for Ultrawideband Wireless Sensor Networks

An energy-efficient adaptive transmission protocol for ultrawideband (UWB) wireless sensor networks (WSNs), called ATP-UWSN, is described and evaluated over time-varying multipath fading channel conditions and multinode interference. Since wireless channels may greatly change from one transmission to the next, the use of fixed transmission parameters for such channels results in wasted energy when channel conditions are good. Adaptation of transmission parameters reduces energy consumption and interference. The proposed ATP-UWSN permits each of the sensor nodes to adapt its code rate and spreading code length (the number of pulses used per data bit) to match the predicted channel-state information (CSI). The transmission parameters are selected in accordance with the predicted CSI characteristics of the communication links in the network to achieve the desired quality of service given by the target bit-error probability. Subsequently, we develop a mathematical adaptation framework for the analytical evaluation of ATP-UWSN. Communication performance is evaluated in terms of average information throughput efficiency, which is a relevant progress-related measure for multi- hop WSNs that is associated with the energy consumption and throughput of a packet transmission. The analytical expression of this performance metric is defined and is used to assess the benefits of the proposed ATP-UWSN when compared with a nonadaptive transmission protocol (NATP) with fixed transmission parameters. Our results show that the ATP-UWSN outperforms the NATP and can improve the robustness of the link and reduce energy consumption by adapting the transmission parameters in response to changes in the predicted CSI.

Low-Complexity Adaptive Transmission for Cognitive Radios in Dynamic Spectrum Access Networks

Cognitive radios that are employed in a network with dynamic frequency assignments must operate efficiently in the presence of uncertainties and variations in the propagation characteristics of the network's communication links. A low-complexity adaptive transmission protocol is described and evaluated for use in cognitive radio networks whose links have unknown and possibly time-varying propagation losses as a result of such phenomena as slow fading or variations in shadowing. The cognitive radios are required to derive only simple statistics in the receivers in order to provide the information that is needed by our protocol; no estimates or measurements of received power or channel gain are used. The protocol's primary mechanism for responding to changes in propagation loss is to adjust the modulation and coding. Because of disruptions that can be caused by higher levels of interference to other radios in the network, the transmitter power is increased only if the most powerful combination of coding and modulation is inadequate. We employ finite-state Markov models for slowly varying channels, and we demonstrate that for such channels our protocol performs nearly as well as an ideal protocol that is told the exact value of the propagation loss for each packet transmission. Thus, the additional complexity that is required to enable cognitive radios to obtain precise channel-gain estimates is not justified and would lead to only negligible improvement in throughput. The throughput of our adaptive transmission protocol is compared with an upper bound that is derived from information theory for a hypothetical ideal protocol that is given perfect channel-state information, and some preliminary results on learning the adaptation decision intervals are included.

Channel and Data Estimation for Ad Hoc Networks and Cognitive Radio

Estimation of channel and data characteristics by the receiver is important in adaptive wireless transmission protocols and in cognitive radio. This paper formulates the estimation problem with the help of an illustrative example from the IEEE 802.11a OFDM standard. The problem reduces to the estimation of the common component variance and mixing probabilities in a finite Gaussian mixture, with known values for component means. Using the known component means, μ1, ... , μ M , a set of non-linear transformations, $${\sinh \mu_i x}$$ and $${\cosh \mu_i x}$$ of the data (mixture random variable X) are used to develop convergent and computationally efficient estimators for both the noise variance and the vector of symbol probabilities. The estimation equations can be implemented recursively or with a batch processing algorithm. Asymptotic variances of the estimates and the Cramer–Rao minimum variance bounds are derived. The estimates converge to true unknowns even when the sequences of noise and data symbols are dependent sequences. The OFDM example is simulated with parameters corresponding to the highest acceptable error rate. For a time-varying channel model chosen from the literature, it is shown that our estimator receives considerably more than adequate amount of data during an average time interval of unchanging channel characteristics. Analytical results, numerical results and related issues are discussed.

A Protocol for Adaptive Transmission in Direct-Sequence Spread-Spectrum Packet Radio Networks

Wireless communication channels may change greatly from one transmission to the next, due to variations in propagation loss and interference. The use of fixed transmission parameters for such channels results in wasted energy when channel conditions are good. Adaptation of the power, code rate, and symbol rate reduces energy consumption and interference caused to other systems. Such adaptation requires information about the characteristics of the channel, which is more difficult to obtain in a packet radio network (PRN) or other mobile ad hoc network than in a typical cellular communication system. We develop methods for providing partial information about the channel state from three statistics that are derived by different subsystems in the receiving terminals of a direct-sequence spread-spectrum PRN. We present and evaluate a protocol that uses this information to adapt the transmission parameters in response to changes in interference and propagation conditions in the network. The performance of the new adaptive-transmission protocol is compared with a system with fixed transmission parameters and with an adaptive protocol that is furnished with perfect knowledge of the channel state at the completion of each transmission.