Saturated Traffic Conditions Research Articles

Shapley’s Value as a Resource Optimization Strategy for Digital Radio Transmission over IBOC FM

The hybrid in-band on-channel (IBOC) transmission system, which serves as a digital audio radio scheme, facilitates the simultaneous transmission of analog FM and digital audio. In IBOC systems, broadcasters transmit signals within allocated channel bands, posing a challenge in bandwidth allocation for digital audio transmission. To address this, cooperative game theory, supported by the bankruptcy game and Shapley’s value, is proposed as a strategy to optimize bandwidth allocation at each node or station. This approach considers service demand, the number of stations, and radio channel conditions in the FM band. The paper presents a scenario under saturated traffic conditions to evaluate the degree of optimization achievable using the Shapley value under clearly defined traffic and channel conditions. The results indicate that cooperative game theory, with the support of the Shapley value, offers an excellent alternative for optimizing bandwidth in digital broadcasting over IBOC in FM, with potential applicability in other digital radio broadcasting systems.

Macroscopic modeling of mixed bi-modal urban networks: A hybrid model of accumulation- and trip-based principles

Network-level traffic flow models either assume steady-state urban flows (i.e. accumulation-based models) or track the movement of all vehicles (i.e. trip-based models). The steady-state assumption present in the accumulation-based models may pose a challenge in light of the multi-modal nature of urban flows. It might be indeed a rough assumption for the flow of some transportation modes like buses, cruising-for-parking vehicles, taxis, and on-demand vehicles. Trip-based models address this concern, however, they need significant parameter calibration effort and are not computationally efficient, which substantially reduces the practicality of these models in real-world applications. Nevertheless, despite the critical importance of developing multi-modal traffic flow models, few attempts have been made to investigate these models in network macroscopic fundamental diagram (NMFD)-related literature. This paper bridges this gap by developing a hybrid network-level traffic flow model for mixed bi-modal (i.e. car and bus) networks. The present hybrid model reproduces the dynamics of car flows via accumulation-based model principles while tracking the movement of buses using the trip-based model. This effort also includes the development of a new FIFO-based entrance function to ensure different modes experience the same delay under saturated traffic conditions. Different numerical experiments are conducted to study the hybrid model performance and to compare it with that of accumulation-based and trip-based models in both steady-state and transition periods under different traffic conditions. Our observations reveal that the hybrid model simulates the dynamics of cars and buses by closely following the behavior of its components under free-flow conditions. The model also outperforms the accumulation-based model under saturated traffic conditions while being considerably less demanding than the trip-based model. A further investigation of the model performance is performed for networks with different bus shares in both free-flow and saturated traffic conditions, confirming the results of the initial numerical experiments. The hybrid model’s computational efficiency is demonstrated. The potential real-world applications of the hybrid model in development of bi-modal network-level simulation models, NMFD-based control strategies along with bus space allocation policies, public transport operation problems, modeling of cruising-for-parking vehicles, taxis, and on-demand vehicles, and modeling and application of autonomous modular vehicles are discussed and future research directions are highlighted.

The Role of Intersection Geometry in Urban Air Pollution Management

Air pollution represents one of the most complex problems of humanity. Traffic contributes significantly to this by emitting large amounts of harmful gases. This problem is particularly pronounced at urban intersections due to frequent changes in vehicle movement dynamics. This paper primarily presents the influence of intersection geometry on pollutant emissions levels. In addition, the influence of various traffic policies promoting greater use of public transport and zero-emission vehicles is also examined. The research combines the field part of recording existing intersections in Sarajevo, Bosnia and Herzegovina with traffic microsimulation. Detailed data on vehicles’ movements were obtained by advanced video processing using the DataFromSky tool, while the PTV Vissim 2022 and Bosch ESTM (2022) software were used to simulate traffic and estimate emissions at geometrically different intersections. The results showed that, in saturated traffic conditions, signalized intersections cause up to 50% lower emissions compared with two-lane and turbo roundabouts and that the impact of the geometric change is more significant than the impact of zero-emission vehicles. In unsaturated conditions, the differences in emissions at different intersections are negligible, with the highest reductions in pollution achieved by using zero-emission vehicles.

Development of Performance Measurement Models for Two-Lane Roads under Vehicular Platooning Using Conjugate Bayesian Analysis

Vehicular platooning is one of the most challenging issues affecting the level of service (LOS) of two-lane roads. This phenomenon has been involved with variables governing performance measures. Thus, to improve the quality of these roads and predict a comprehensive model for future plans under this phenomenon, the present study aimed to evaluate the effect of vehicular platooning variables on performance measures and then identify the critical headways of vehicular platooning associated with the vehicle-gap-acceptance behavior. Multiple linear regression (MLR) and Bayesian linear regression (BLR) models were used to develop performance measurement models that are based on conjugate Bayesian analysis. The vehicular platooning was formed in the threshold of a time headway of 2.4 s. According to a comparative evaluation of the developed models, the best predictive model was found between the traffic flow and the number of followers per capacity (NFPC). In addition, the BLR model showed a higher accuracy rate in predicting NFPC compared with the MLR model due to low errors and high prediction performance. Thus, NFPC was introduced as a surrogate performance measure, which had a premier capability to predict the LOS for unsaturated and saturated traffic conditions compared with the two performance measures from the Highway Capacity Manual (2010), including percent time spent following and average travel speed.

MRCN: Throughput-Oriented Multicast Routing for Customized Network-on-Chips

The relentless proliferation of Big Data and artificial intelligence has compelled computing platform architectures to evolve into heterogeneous multicores for greater energy efficiency. A customized network-on-chip (NoC) supporting interconnection diversity is pivotal for the asymmetric data-access traffic requirements of modern heterogeneous multicore system-on-chip (SoC). A significant portion of on-chip data access comprises single-source multi-destination (SSMD) traffic, which supports barrier synchronization, multi-threading, cache coherency protocols, and deep neural network (DNN) acceleration. By amortizing SSMD traffic, multicast routing is essential for effectively utilizing communication bandwidth. One of the primary concerns in supporting multicast routing in NoCs is to circumvent the additional deadlock conditions caused by branch operations among the active routers. However, it is challenging to implement the throughput-optimized multicast routing in irregular topology-based NoCs because the deadlock conditions become highly complicated, and the Hamiltonian path required to apply the labeling rule may not exist. Two important observations were identified regarding multicast routing in customized NoCs: 1) Even if the NoC lacks a Hamiltonian path, deadlock-freedom can be guaranteed by restricting branch operations to a specific destination. 2) A variable path diversity in a custom topology can be leveraged in routing path allocation and branch. Based on these properties, this study proposes a deadlock-free and throughput-enhanced multicast routing for customized NoC (MRCN). MRCN ensures deadlock freedom by utilizing extended routing and router labeling rules. Furthermore, destination router partitioning and traffic-aware adaptive branching are incorporated to reduce packet routing hops and disperse channel traffic. The effectiveness of MRCN was verified using Noxim, a well-known cycle-accurate NoC simulator, under various topologies and traffic patterns. The simulation revealed that MRCN improved the average latency by 13.98 % and the throughput by 12.16 % under the saturated traffic conditions over the previous multicast routings in customized NoCs.

An Adaptive and Spectrally Efficient Multi-Channel Medium Access Control Protocol for Dynamic Ad Hoc Networks.

Medium access control (MAC) protocols in ad hoc networks have evolved from single-channel independent transmission mechanisms to multi-channel concurrent mechanisms to efficiently manage the demands placed on modern networks. The primary aim of this study is to compare the performance of popular multi-channel MAC (MMAC) protocols under saturated network traffic conditions and propose improvements to the protocols under these conditions. A novel, dynamically adaptive MMAC protocol was devised to take advantage of the performance capabilities of the evaluated protocols in changing wireless ad hoc network conditions. A simulation of the familiar MAC protocols was developed based on a validated simulation of the IEEE 802.11 standard. Further, the behaviors and performances of these protocols are compared against the proposed MMAC protocols with a varying number of ad hoc stations and concurrent wireless channels in terms of throughput, Jain's fairness index, and channel access delay. The results show that the proposed MMAC protocol, labeled E-SA-MMAC, outperforms the existing protocols in throughput by up to 11.9% under a constrained number of channels and in channel access delays by up to 18.3%. It can be asserted from these observations that the proposed approach provides performance benefits against its peers under saturated traffic conditions and other factors, such as the number of available wireless channels, and is suitable for dynamic ad hoc network deployments.

An Analytical Model for the Aggregate Throughput of IEEE 802.11ah Networks under the Restricted Access Window Mechanism.

The IEEE 802.11ah is an amendment to the IEEE 802.11 standard to support the growth of the Internet of Things (IoT). One of its main novelties is the restricted access window (RAW), which is a channel access feature designed to reduce channel contention by dividing stations into RAW groups. Each RAW group is further divided into RAW slots, and stations only attempt channel access during the RAW slot they were assigned to. In this paper, we propose a discrete-time Markov chain model to evaluate the average aggregate throughput of IEEE 802.11ah networks using the RAW mechanism under saturated traffic and ideal channel conditions. The proposed analytical model describes the behavior of an active station within its assigned RAW slot. A key aspect of the model is the consideration of the event of RAW slot time completion during a station’s backoff operation. We study the average aggregate network throughput for various numbers of RAW slots and stations in the network. The numerical results derived from our analytical model are compared to computer simulations based on an IEEE 802.11ah model developed for the ns-3 simulator by other researchers, and its performance is also compared to two other analytical models proposed in the literature. The presented results indicate that the proposed analytical model reaches the closest agreement with independently-derived computer simulations.

Performance analysis of the unslotted IEEE 802.15.4k MAC protocols under saturated traffic and fading channel conditions

Performance analysis of the unslotted IEEE 802.15.4k MAC protocols under saturated traffic and fading channel conditions

A Markov model for IEEE 802.15.4 MAC protocol with energy-efficient GTS utilization under saturated and unsaturated traffic conditions

In the present work, we have proposed an analytical Markov-chain model of the modified slotted Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) IEEE 802.15.4 Medium Access Control (MAC) protocol, which efficiently utilizes the Guaranteed Time Slots (GTSs) under saturated traffic conditions. The five dimensional Markov chain model based analysis is performed for variable Contention Access Period (CAP). Two constraints are introduced i.e. Global Utilization Factor (GUF) and Local Utilization Factor (LUF), to adjust the duration of CAP in each cycle. The work mainly focuses on utilization of GTS under saturated traffic condition for high traffic load applications. To evaluate the performance of our proposed model, we have compared the performance with Misic’s model of standard IEEE 802.15.4 MAC protocol. In addition, the analysis is carried out for practical networks where the data traffic is bursty in nature. The results reflect that our proposed algorithm improves the throughput of the IEEE 802.15.4 MAC protocol in energy-efficient manner at high traffic load applications.

A fuzzy logic simulation model for controlling an oversaturated diverge diamond interchange and ramp metering system

Traffic congestion is a global problem that cannot be solved by continuing to add new roads and extra capacity, which is accentuated in the areas where roads of unlimited-access (e.g. arterial streets) interface those of limited-access (e.g. freeways). Many researchers have addressed this problem but we present here a novel method to utilize a fuzzy logic model to reduce traffic congestion in such interfacing areas during saturated traffic conditions. More specifically this paper presents a control method for a complex traffic control system: Diverging Diamond Interchange (DDI) - Ramp Metering (RM), under oversaturated traffic conditions. The DDI is a relatively new concept of an alternative intersection geometry where two intersections serve left-turn movements without conflicts. However, such DDI left-turn movements, along with the right-turn movements from the opposite direction, put additional ‘pressure’ on the on-ramp of the freeways or multilane highways that intersect with DDIs. If freeway operations are saturated or near saturation, which may be the result of RM operations, this type of traffic control system can lead to a fully jammed condition with a potential spillback. The purpose of the proposed fuzzy-logic control is to prevent such a queue spillback from the metering ramp to the DDI. After presenting the fuzzy-logic control (FLC) model, we compare it to the conventional fixed time control (FTC) to evaluate potential benefits. To assess the quality of proposed analytical solutions in the real-traffic-like environment we evaluated the two logics in a VISSIM microsimulation model. The results show that, when compared to FTC, the FLC method improves traffic conditions moderately but in the oversaturated environment where there is very little room for improvement.

EVALUASI KINERJA JALAN NASIONAL TERHADAP KARAKTERISTIK LALU LINTAS PADA RUAS JALAN NASIONAL KOTA PALEMBANG

The roads transportation is an important infrastructure as one of the land transportation infrastructures for the movement of social activities and to support economic development, specifically in Palembang City. The population growth of Palembang City has resulted in an increase in the number of vehicles and highway users. As a result, transportation activities in Palembang, especially at Parameswara roads are increasing. The impact of this, there will be heavy traffic volume, resulting in conflicts on the road, which lead to traffic accidents. Therefore, there will be congestion and a decrease in the performance of the road speed.The research is conducted at Parameswara Road in Palembang that visually diminished the ability to accommodate the road traffic volume per day, accordingly the effect of traffic that occurs due to the lack of road capacity as the sequence of large volume traffic. The purpose of this study is to determine the capacity and level of road services to carried out the performance value on this road. The method used in the analysis is the Greenshield model, Greenberg, and Underwood. This study explains the maximum volume at peak hour that develop on Monday is between 1561 smp/hour and 1549 smp/hour. Whereas the lowest is around 1225 smp/hour and 1008 smp/hour that occurs on Sunday. Therefore, the analysis of service level on the research years at Parameswara Road depicts the saturated traffic conditions and low starting speed with D service index category and service level analysis at 10 years of planning time projections, the lpda result is from 2022 to 2026, The Parameswara road conditions at E and F service index categories are the traffic jam circumstances and slight speed. Hence, it necessitates constructing a non-plot way at Parameswara Road intersection to tackle this traffic congestion.Keywords: Greenshield, Greenberg, Underwood, Road Capacity.

A comparative analysis of the performance of turbo roundabouts based on geometric characteristics and traffic scenarios

ABSTRACT This study aimed to investigate the effect of geometric characteristics and traffic scenarios on the performance measures, including delay, volume to capacity (v/c) ratio, capacity, and the level of service (LOS) in basic and rotor turbo roundabouts. In addition, it attempted to compare turbo roundabouts using performance measures based on geometric characteristics and traffic scenarios. The results showed that performance measures reduced significantly by increasing the diameter of four-leg turbo roundabouts although they improved in three-leg turbo roundabouts. Further, four- and three-leg basic turbo roundabouts had a better performance by changing the balanced to imbalanced traffic flow scenario compared with four- and three-leg rotor turbo roundabouts. Additionally, substituting four- and three-leg basic turbo roundabouts for rotor four- and three-leg turbo roundabouts increased the performance measures. Overall, the basic turbo roundabouts had a better performance compared to the rotor turbo roundabout under unsaturated and saturated traffic conditions .

Operational and Safety Impact Analysis of Implementing Emergency Shoulder Use (ESU) for Hurricane Evacuation

The emergency shoulder use (ESU) was implemented in Florida in September 2017 to facilitate mass evacuation before Hurricane Irma made landfall on the shores of Florida. ESU was implemented on the northbound I-75 for about 39 h and eastbound I-4 for about 6 h when the left shoulders were opened for use as travel lanes. This study discusses the operational and safety effects of ESU. The operational effects of ESU were studied and compared with other alternatives including one-way operation (contraflow) and both left and right shoulder use. The findings showed the left shoulder ESU could be an effective alternative to one-way operation. The one-way operation was not a preferred method as it can only be operated during the day time, requires massive resource allocation, and hampers emergency services reaching to different parts of the state. However, ESU on the left shoulder offers minimal disturbance to traffic and is easy to deploy. The safety impact analysis was performed by conducting a descriptive statistical comparison of crash types, severity, and other relevant factors during ESU operations. The crash analysis showed that the observed number of crashes on an urban I-75 segment during ESU operation is commensurate with normal operation with saturated traffic conditions, in contrast a rural segment experienced a higher observed crash rate than the predicted rate with saturated traffic conditions. The predictive analysis of ESU crashes also showed that ESU implementation helped to reduce the expected number of crashes significantly.

Parallel PPDU Transmission Mechanism for Wideband Wireless LANs

When the preambles of a wideband 802.11n/ac frame transmission are affected by a collision with a 20MHz frame on one of the subchannels, a receiver might fail to decode the whole wideband frame. Experimental evaluations with off-the-shelf 802.11n hardware showed that the vulnerability of wideband frame transmission to a narrowband collision/interference is a real problem. To mitigate the severe impact of narrowband collision/interference on wideband transmission, we propose to transmit several 20MHz frames in parallel instead of a single wideband frame so that a narrowband collision on one of the subchannels affects only the parallel frame transmitted on that subchannel. Performance evaluations demonstrated that the proposed parallel frame transmission scheme significantly improves the throughput and delay performance of wideband transmissions under different traffic and channel conditions. While the throughput performance of the proposed scheme for saturated traffic conditions was analytically validated, extensive simulation-based evaluations showed that the proposed scheme achieves great performance improvement for unsaturated traffic conditions and hidden node environment.

Saturated Throughput Analysis of IEEE 802.11ad EDCA For High Data Rate 5G-IoT Applications

The recently developed IEEE 802.11ad (WiGig) standard offers multi-Gbps connectivity for consumer wireless local area networks and operates in the millimeter wave frequency band (around 60 GHz). It supports two different contention-based channel access mechanisms, namely distributed coordination function, which offers fair service for every station, and the enhanced distributed channel Access (EDCA) for offering service differentiation among the stations. In this paper, we study the throughput performance of the IEEE 802.11ad EDCA mechanism under saturated traffic conditions using both analytical and simulation models. A novel five-dimensional Markov chain developed is used for analytically modeling the throughput behavior of the IEEE 802.11ad EDCA in the presence of virtual antenna sectors, high-gain directional beamforming, and presence of contention and contention-free access periods. Using this developed analytical model, the effect of the number of sectors, number of stations, arbitration inter-frame space, packet length, and minimum contention window size on the throughput of the four different access or service categories present in the EDCA under saturated traffic conditions, is investigated. When compared with the simulation outcomes, the proposed analytical model accurately analyzes the network performance by achieving less than 4% error.

Modelling a vehicle‐ID‐based IEEE 802.11OCB MAC scheme for periodic broadcast in vehicular networks

Periodic broadcast of cooperative awareness messages (CAMs) is of great importance considering safety-related applications, for a network like VANET. This study proposes a vehicle-identifier (ID)-based MAC scheme for the periodic broadcast of CAMs in a vehicular network. Each CAM generated by a vehicle is associated with a unique ID. This study uses this attribute of CAM messages while participating in the channel assessment procedure. Each vehicle weighs the random back-off number with the unique ID incorporated in their respective CAM. This eventually leads to the selection of a vehicle-ID-based random back-off number, mitigating all possible probabilities of collision due to same back-off number selection. The simulation is performed considering saturated traffic conditions, to analyse its behaviour under most critical situations. The proposed model eliminates the chances of selecting zero as the initial back-off number, eliminating any chances of consecutive freeze process. The proposed one-dimensional Markovian model is validated by MATLAB. The proposed model provides a clear depiction that it performs better than the traditional IEEE 802.11OCB used for VANET. Also, it is worth noting that the achieved results outperform the existing work in terms of average packet delay since nearly one-fourth of the contention window size is utilised throughout the simulation.

Traffic Signal Timing Optimization for Heterogeneous Traffic Conditions Using Modified Webster’s Delay Model

Indian traffic is typically composed of different vehicle classes like motorized two-wheelers, three-wheelers, four-wheelers, and non-motorized modes, which vary widely in their static and dynamic characteristics. Such diverse group of vehicle classes sharing of the same right-of-way (ROW) results in a type of traffic behaviour called “gap filling” and “virtual lane”. At signalized intersections, this behaviour is manifested by the Probably-First-In-Probably-First-Out (PFIPFO) queuing behaviour, which has been defined and described in this paper. A literature review of the topic reveals that previous delay models have focused on homogeneous traffic conditions and cannot be used for the heterogeneous traffic conditions in countries like India without significant modifications. Basic Webster’s delay model is among the most widely used around the world, including India, for designing and evaluation of signalized intersections. In this model, the signalized intersection is treated as an M/D/1 queuing system with constant (or deterministic) service times and random arrival times. While this is a reasonable model for lane-disciplined, car-dominated traffic, its suitability for the heterogeneous traffic in India is dubious, as the service times are also rendered random in this case by the differences in vehicle characteristics. Hence an M/M/1 or M/M/N queuing model is more appropriate in such scenario. Considering these points, it is therefore necessary to modify Webster’s basic delay model to make it suitable for heterogeneous, weakly lane-disciplined, saturated traffic conditions in India. In the present study, a new model for random delay component using multichannel queuing theory and PFIPFO queuing behaviour is derived for Indian traffic conditions. The proposed model is validated using the results from a micro-simulation and finally it is used to optimize the traffic signal timing for three intersections in Bangalore city.

Joint spatial multiplexing and transmit diversity in MIMO ad hoc networks

This paper investigates the performance of MIMO ad hoc networks that employ transmit diversity, as delivered by the Alamouti scheme, and/or spatial multiplexing, according to the Vertical Bell Labs Layered Space-Time system (V-BLAST). Both techniques are implemented in the ns-3 network simulator by focusing on their overall effect on the resulting signal-to-interference-plus-noise ratio (SINR) at the intended receiver. Unlike previous works that have studied fully-connected scenarios or have assumed simple abstractions to represent MIMO behavior, this paper evaluates MIMO ad hoc networks that are not fully connected by taking into account the impact of multiple antennas on the carrier sense activity in CSMA-like medium access control (MAC) protocols. In addition to presenting a performance evaluation of ad hoc networks operating according to each individual MIMO scheme, this paper proposes simple modifications to the IEEE 802.11 DCF MAC to allow the joint operation of both MIMO techniques. Hence, each pair of nodes is allowed to select the best MIMO configuration for the impending data transfer. The joint operation is based on three operation modes that are selected based on the estimated SINR at the intended receiver and its comparison with a set of threshold values. The performance of ad hoc networks operating with the joint MIMO scheme is compared with the performance when using each individual MIMO scheme and the standard single-input single output (SISO) IEEE 802.11. Performance results are presented based on MAC-level throughput per node, delay, and throughput fairness under saturated traffic conditions.

Performance Analysis of M2M Data Collection Networks Using Dynamic Frame-Slotted ALOHA

We are witnessing an explosion in the growth of the number of connected devices, with the consequent increase of their share in global energy consumption. Thus, it is mandatory that we employ green networking technologies for Internet of Things and machine to machine (M2M) networks. In M2M data collection networks, hundreds or thousands of devices communicate with a data collector (DC). In this regard, dynamic frame slotted Aloha (DFSA) has gained popularity as an energy efficient MAC protocol for M2M data collection networks. In this paper, we carry out performance evaluation of DFSA algorithm. First, we derive analytical bounds on the performance of DFSA. To this end, we employ the properties of binomial distributions and Karp–Upfal–Widgerson inequality. Furthermore, we propose a simple MAC protocol based on DFSA, and analyze the protocol under saturated traffic condition. Using a mathematical model for our proposed protocol, we derive closed form expressions for system throughput, packet delay, and the energy efficiency of the node and the DC. The analysis is validated through extensive simulation.

A Novel Spectrally Efficient Asynchronous Multi-Channel MAC Using a Half-Duplex Transceiver for Wireless Networks

Multi-channel medium access control (MAC) protocols maximize network performance by enabling concurrent wireless transmissions over non-interfering channels. Despite physical layer advancements, the underlying IEEE 802.11 MAC standard cannot fully exploit features and support high-performance applications. In this work, we propose the novel spectrally efficient asynchronous multi-channel MAC (SA-MMAC) protocol for wireless networks using a single half-duplex transceiver. A full-duplex mode of operation on data channels reduces the signaling overhead and boosts the spectrum efficiency. A revamped contention mechanism of IEEE 802.11 addresses the multi-channel hidden terminal problem, and a jamming signal from the receiver addresses the collisions in control signals. Furthermore, the control channel is used for data transmissions to increase the bandwidth utilization but under a restricted half-duplex mode to avoid causing a bottleneck situation. The simulator is tested for correctness. The results suggest that the protocol can work well on 3, 4, or 12 concurrent channels with high node density, providing about 12.5 times more throughput than IEEE 802.11 and 18% to 95% more throughput than its multi-channel variants under saturated traffic conditions.