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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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      <title>Channel Characterization at 2.4 GHz for Aerial Base Station</title>
      <link>https://trid.trb.org/View/1626407</link>
      <description><![CDATA[The paradigm shift towards high data rate demands of mobile users in IMT-2020 commonly known as 5G, led to the possibility of using Aerial Base Stations (ABS) to fulfill such requirements. However, for implementation of ABS, an appropriate air-to-ground channel model is needed. It is an important factor to incorporate the understanding of the channel fading behavior before designing the system. In this article, the authors present novel channel propagation results obtained from ray tracing simulations for different environments, such as Suburban, Urban and Urban-High-Rise, according to  International Telecommunications Union (ITU) Radio-communication parameters. The details of different channel characteristics such as Spatial Correlation and Cumulative Distribution Function for Small Scale Parameters as Delay Spread and Angle-of-Arrival are presented for different ABS heights. The authors also focus on various channel modeling approaches and frameworks for 3D channel models.]]></description>
      <pubDate>Mon, 29 Jul 2019 10:32:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/1626407</guid>
    </item>
    <item>
      <title>Distributed transmission power control for communication congestion control and awareness enhancement in VANETs</title>
      <link>https://trid.trb.org/View/1590402</link>
      <description><![CDATA[The vehicular ad hoc network (VANET) has been identified as one of the most promising technologies for managing future intelligent transportation systems. This paper proposes a distributed transmission power adjustment algorithm for communication congestion control and awareness enhancement to address communication congestion problems that can arise in VANETs. The objective of the proposed algorithm is to provide maximum awareness of surrounding vehicles' status while maintaining a communications channel load below the allowed threshold. The proposed algorithm accomplishes this by adjusting the transmission range of each vehicle in the network progressively and gradually, while monitoring the communications channel load of each vehicle. By changing the transmission range of a vehicle little by little according to the communications channel load of its neighboring vehicles, the algorithm finds the optimal transmission range that provides maximum awareness without resulting in communications congestion. In addition, the proposed algorithm appropriately controls the channel load in a fair manner without sacrificing awareness of specific vehicles in the congested situation. This allows nearby vehicles to obtain more peripheral information to help them stay away from potential hazards and maintain safety. The proposed algorithm was implemented in a simulation environment, and its performance was validated in various traffic scenarios. The simulation results show that the proposed algorithm can deal with communication congestion by controlling the transmission power fairly to a target threshold in various traffic situations.]]></description>
      <pubDate>Fri, 29 Mar 2019 10:15:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1590402</guid>
    </item>
    <item>
      <title>Space Shift Keying Transmission for Intervehicular Communications</title>
      <link>https://trid.trb.org/View/1436123</link>
      <description><![CDATA[In this paper, the authors investigate the performance of space shift keying (SSK) transmission over a generalized multiple scattering channel. This channel model provides a realistic statistical description of an intervehicular communication environment and includes as special cases the Rician, Rayleigh, and double-Rayleigh channels. The authors derive an accurate closed-form expression for the pairwise error probability of SSK, which is used to obtain the uncoded and coded error rate performances of SSK over various propagation scenarios. An asymptotic analysis for high values of the signal-to-noise ratio is carried out to determine the diversity and coding gains of the proposed system. The performance analysis reveals the impact of the number of receive antennas and the use of soft and hard decision decoding on the error rate performance of the SSK transmission over multiple scattering channels. Various numerically evaluated results accompanied by Monte Carlo simulations are presented to demonstrate the correctness of the proposed analysis.]]></description>
      <pubDate>Tue, 24 Jan 2017 15:15:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1436123</guid>
    </item>
    <item>
      <title>A Cooperative Channel Reservation MAC Protocol with Adaptive Power Control and Carrier Sensing</title>
      <link>https://trid.trb.org/View/1429323</link>
      <description><![CDATA[In Vehicular Ad hoc Networks (VANET), wireless channel is a multidimensional resource, involved in time, frequency, space, code and etc. In this paper, a novel channel reservation Medium Access Control (MAC) protocol, called A-CCRM, is proposed to jointly reserve the channel resource in both time domain and space domain. In A-CCRM, the channel reservation time period is computed according to the periodicity of real-time traffics, and the channel reservation space is adjusted by jointly using the techniques of both power control and carrier sensing. Moreover, in order to improve the stability of channel reservation, the annouced channel reservation information is cooperatively relayed by the neighboring nodes of the transmitter. Simulation results show that compared with other MAC protocols based on channel reservation mechanisms, A-CCRM performs better in terms of throughput, energy efficiency and packet lost rate.]]></description>
      <pubDate>Mon, 21 Nov 2016 13:24:58 GMT</pubDate>
      <guid>https://trid.trb.org/View/1429323</guid>
    </item>
    <item>
      <title>Intelligent Vehicle Communication: Deterministic Propagation Prediction in Transportation Systems</title>
      <link>https://trid.trb.org/View/1422645</link>
      <description><![CDATA[Intelligent transportation systems (ITSs) are currently under intense research and development for making transportation safer and more efficient. The development of such vehicular communication systems requires accurate models for the propagation channel. A key characteristic of these channels is their temporal variability and inherent time-changing statistics, which have a major impact on electromagnetic propagation prediction.]]></description>
      <pubDate>Fri, 23 Sep 2016 11:17:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1422645</guid>
    </item>
    <item>
      <title>Mutual Coupling Research of Multi-antenna in Dual-Channel Balise</title>
      <link>https://trid.trb.org/View/1406384</link>
      <description><![CDATA[The data capacity of Euro-balise is 1023 bit, which could not fully satisfy the demanding in field as the existing railway in China is more complicated than that in Europe. This paper proposes a dual-channel balise. Compared with Euro-balise which has one uplink antenna, the new balise adopts two independent uplink antennas with two uplink channels and the data capacity is 2046 bit. Based on electromagnetic field theory, multiple antennas are equivalent to a multi-port network. The S-parameters are simulated and the isolation or mutual coupling among three antennas is analyzed. The distance between two antennas and operation frequency difference are the main influencing factors of mutual coupling. The experiment is implemented on the test platform, the results indicate that the interaction of multi-antenna do not influence the normal work of dual-channel balise.]]></description>
      <pubDate>Wed, 13 Jul 2016 11:42:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1406384</guid>
    </item>
    <item>
      <title>Structuring Cooperative Behavior Planning Implementations for Automated Driving</title>
      <link>https://trid.trb.org/View/1406316</link>
      <description><![CDATA[Cooperative behavior planning for automated vehicles is getting more and more attention in the research community. This paper introduces two dimensions to structure cooperative driving tasks. The authors suggest to distinguish driving tasks by the used communication channels and by the hierarchical level of cooperative skills and abilities. In this manner, this paper presents the cooperative behavior skills of "Jack", the authors' automated vehicle driving from Stanford to Las Vegas in January 2015.]]></description>
      <pubDate>Tue, 28 Jun 2016 12:54:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1406316</guid>
    </item>
    <item>
      <title>Rate Request Sequenced Bit Loading Secondary User Reallocation Algorithm for DMT Systems in Cognitive Radio</title>
      <link>https://trid.trb.org/View/1403828</link>
      <description><![CDATA[A rate request sequenced bit loading reallocation algorithm is proposed. The spectral holes detected by spectrum sensing (SS) in cognitive radio (CR) are used by secondary users. This algorithm is applicable to Discrete Multitone (DMT) systems for secondary user reallocation. DMT systems support different modulation on different subchannels according to Signal-to-Noise Ratio (SNR). The maximum bits and power that can be allocated to each subband is determined depending on the channel state information (CSI) and secondary user modulation scheme. The spectral holes or free subbands are allocated to secondary users depending on the user rate request and subchannel capacity. A comparison is done between random rate request and sequenced rate request of secondary user for subchannel allocation. Through simulations it is observed that with sequenced rate request higher spectral efficiency is achieved with reduced complexity.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:42:55 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403828</guid>
    </item>
    <item>
      <title>Spectrum Search Over Multiple Homogeneous Channels</title>
      <link>https://trid.trb.org/View/1372265</link>
      <description><![CDATA[The authors consider spectrum detection in multiple homogeneous two-state channels. At each time, a secondary user (SU) can simultaneously detect multiple channels with imperfect spectrum detectors. The objective of the SU is to obtain the idle channels as quickly as possible under a false detection constraint. This detection problem is formulated as a restless multiarmed bandit (RMAB) problem that is proven to be PSPACE-hard. A feasible approach, namely myopic policy, is to detect the best channels until idle channels are caught. In this paper, the authors establish the structure of the myopic policy, prove that the myopic policy is optimal in the case of detecting N - mbox1 of N channels under certain mild assumptions, and further show that the myopic policy is not optimal generally by constructing a counterexample.]]></description>
      <pubDate>Mon, 02 Nov 2015 09:18:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/1372265</guid>
    </item>
    <item>
      <title>Distributed Irregular Codes Relying on Decode-and-Forward Relays as Code Components</title>
      <link>https://trid.trb.org/View/1372237</link>
      <description><![CDATA[A near-capacity distributed coding scheme is conceived by incorporating multiple relay nodes (RNs) for constructing a virtual irregular convolutional code (IRCC). The authors first compute the relay channel's capacity and then design IRCCs for the source and relay nodes. Extrinsic information transfer (EXIT) charts are utilized to design the codes for approaching the achievable capacity of the relay channels. Additionally, the authors improve the transmit power efficiency of the overall system by invoking both power allocation and relay selection. They found that even a low-complexity repetition code or a unit-memory convolutional code is capable of forming a near-capacity virtual IRCC. The performance of the proposed distributed IRCC (DIRCC) scheme is shown to be perfectly consistent with that predicted from the EXIT chart. More specifically, the DIRCC scheme is capable of operating within 0.68 dB from the corresponding lower bound of the relay channel capacity, despite the fact that each RN is exposed to realistic decoding errors due to communicating over imperfect source–relay channels.]]></description>
      <pubDate>Tue, 27 Oct 2015 09:59:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/1372237</guid>
    </item>
    <item>
      <title>Dynamic Deployment of Small Cells in TV White Spaces</title>
      <link>https://trid.trb.org/View/1369928</link>
      <description><![CDATA[The operation of small cells in TV white spaces (TVWSs) represents a coexistence challenge due to their unplanned deployment, their heterogeneous transmission technologies, and the scarcity of TVWS channels in crowded cities. Whenever a new small cell is switched on, a spectrum reassignment of already-deployed small cells can be used to avoid high interference and enable coexistence. However, as users may turn on and off their small cells at times, these reassignments may lead to frequent reconfigurations of already-deployed small cells. For this reason, a solution named small-cell dynamic deployment (SCDD) is designed to reassign TVWS channels only to the small cells in the neighborhood of the new cell. A channel allocation is proposed for SCDD formulated as an exact potential game. Its exact potential function is the sum of the average capacity of the small cells considered in the game. Results show that SCDD requires a few channel reconfigurations of already-deployed small cells because the channel assignment outside the neighborhood of the new cell remains unchanged. However, SCDD performs similarly to the case in which the allocation may modify the channels of all small cells already deployed.]]></description>
      <pubDate>Fri, 23 Oct 2015 09:22:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1369928</guid>
    </item>
    <item>
      <title>Vehicular Communications: Survey and Challenges of Channel and Propagation Models</title>
      <link>https://trid.trb.org/View/1354320</link>
      <description><![CDATA[Vehicular communication is characterized by a dynamic environment, high mobility, and comparatively low antenna heights on the communicating entities (vehicles and roadside units). These characteristics make vehicular propagation and channel modeling particularly challenging. In this article, the authors classify and describe the most relevant vehicular propagation and channel models, with a particular focus on the usability of the models for the evaluation of protocols and applications. The authors first classify the models based on the propagation mechanisms they employ and their implementation approach. The authors also classify the models based on the channel properties they implement and pay special attention to the usability of the models, including the complexity of implementation, scalability, and the input requirements (e.g., geographical data input). The authors also discuss the less-explored aspects in vehicular channel modeling, including modeling specific environments (e.g., tunnels, overpasses, and parking lots) and types of communicating vehicles (e.g., scooters and public transportation vehicles). The authors conclude by identifying the under researched aspects of vehicular propagation and channel modeling that require further modeling and measurement studies.]]></description>
      <pubDate>Thu, 21 May 2015 16:06:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1354320</guid>
    </item>
    <item>
      <title>Power-Line Communication: Channel Characterization and Modeling for Transportation Systems</title>
      <link>https://trid.trb.org/View/1354311</link>
      <description><![CDATA[This article provides an overview of the recent advances in the characterization and modeling of power-line communication (PLC) channels in transportation systems. The salient aspects of the topological and functional features of the data channels using power networks of motor vehicles, spacecraft, and aircraft are presented. This article is tutorial in nature and guides the reader through a selection of recent papers, collecting relevant results needed to assess the feasibility and strengths of PLC for this class of applications.]]></description>
      <pubDate>Wed, 20 May 2015 13:47:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1354311</guid>
    </item>
    <item>
      <title>Unmanned Aircraft Systems: Air-Ground Channel Characterization for Future Applications</title>
      <link>https://trid.trb.org/View/1354317</link>
      <description><![CDATA[Unmanned aircraft systems (UASs) are being used increasingly worldwide. These systems will operate in conditions that differ from conventional piloted aircraft, and this implies that the airground (AG) channel for UASs can differ significantly from the traditional, simple, AG channel models. After providing some background and motivation, the authors describe the AG channel features and their efforts in measuring and modeling the AG channel. Some example measurement and model results-for the path loss and the Ricean K-factor-are provided to illustrate some of the interesting AG channel characteristics that are still being investigated.]]></description>
      <pubDate>Wed, 20 May 2015 13:47:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1354317</guid>
    </item>
    <item>
      <title>Constructed Data Pilot-Assisted Channel Estimators for Mobile Environments</title>
      <link>https://trid.trb.org/View/1347932</link>
      <description><![CDATA[Nowadays, more and more communication systems are deployed under mobile environments with very high velocity. This paper focuses on the channel estimation problem in vehicular scenarios, which is very challenging in view of the extremely time-varying characteristics of mobile channels. Specifically, the authors propose a novel channel estimator named constructed data pilot (CDP) estimator for the current communication standards by fully exploiting the channel correlation characteristics across two concatenated symbols. On the basis of the CDP estimator, the authors further resort to two efficient techniques to improve its performance over the entire signal-to-noise-ratio (SNR) region. For the first technique, the time-variant mobile channel is modeled as a first-order Markov process so that the exact autocorrelation value of the two adjacent symbols can be derived. For the second technique, the SNR is estimated and serves as a priori information. Simulation results reveal that the proposed channel estimators outperform existing alternatives with lower computational complexity.]]></description>
      <pubDate>Mon, 27 Apr 2015 09:55:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1347932</guid>
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