Capacity analysis

arXiv:cs/0612076v1 [cs.IT] 15 Dec 2006 SUBMITTED TO IEEE TRANSACTIONS ON INFORMATION THEORY 1 A New Approach for Capacity Analysis of Large DimensionalMulti-Antenna Channels W. Hachem(∗), O. Khorunzhiy, Ph. Loubaton, J. Najim and L. Pastur ...

We present a simple queueing model to analyze the SMS capacity of a GSM cellular network. The analy- sis is based on a detailed study of GSM channels and their usage by SMS and other traffic. We saw that SMS is sent on the same control channels that are used by voice call set-up and location updates. Our results show

Advanced Driver Assistance Systems (ADAS) offer the possibility of helping drivers to fulfill their driving tasks. Automated vehicles are capable of communicating with surrounding vehicles (V2V) and infrastructure (V2I) in order to collect and provide essential information about driving environment.
Studies have proved that automated vehicles have a potential to decrease traffic congestion on road networks by reducing the time headway, enhancing the traffic capacity and improving the safety margins in car following. Furthermore, vehicle movement and driver’s behavior of conventional vehicles will be affected by the presence of automated vehicles in traffic networks. Despite different encouraging factors, automated driving raises some concerns such as possible loss of situation awareness, overreliance on automation and degrading driving skills in absence of practice. Moreover, coping with complex scenarios, such as merging at ramps and overtaking, in terms of interaction between automated vehicles and conventional vehicles need more research.
This thesis work aims to investigate the effects of automated vehicles on driver’s behavior and traffic performance. A broad literature review in the area of driving simulators and psychological studies was performed to examine the automated vehicle effects on driver’s behavior. Findings from the literature survey, which has been served as setup values in the simulation study of the current work, reveal that the conventional vehicles, which are driving close to the platoon of automated vehicles with short time headway, tend to reduce their time headway and spend more time under their critical time headway. Additionally, driving highly automated vehicles is tedious in a long run, reduce situation awareness and can intensify driver drowsiness, exclusively in light traffic. In order to investigate the influences of automated vehicles on traffic performance, a microscopic simulation case study consisting of different penetration rates of automated vehicles (0, 50 and 100 percentages) was conducted in VISSIM software. The scenario network is a three-lane autobahn segment of 2.9 kilometers including an off-ramp, on-ramp and a roundabout with some surrounding urban roads.
Outputs of the microscopic simulation in this study reveal that the positive effects of automated vehicles on roads are especially highlighted when the network is crowded (e.g. peak hours). This can definitely count as a constructive point for the future of road networks with higher demands. In details, average density of autobahn segment remarkably decreased by 8.09% during p.m. peak hours in scenario with automated vehicles. Besides, Smoother traffic flow with less queue in the weaving segment was observed. Result of the scenario with 50% share of automated vehicles moreover shows a feasible interaction between conventional vehicles and automated vehicles. Meaningful outputs of this case study, based on the input data from literature review, demonstrate the capability of VISSIM software to simulate the presence of automated vehicles in great extent, not only as an automated vehicle scenario but also a share of them, in traffic network. The validity of the output values nonetheless needs future research work on urban and rural roads with different traffic conditions.

Brezilya, Rusya, Hindistan, Çin ve Güney Afrika devletlerinin baş harflerinden oluşan BRICS dünya ekonomisinde en hızlı gelişen “yükselen piyasaları” olarak kabul edilmektedir. BRICS ülkelerinin, geniş yüzölçümü, büyük nüfus, hızlı ekonomik büyüme gibi çok sayıda ortak özelliği bulunmaktadır. 2010’lı yıllarda Türkiye’nin gruba dâhil olması konuşulurken, Güney Afrika’nın katılımı ile grup BRICS halini almıştır. Bununla beraber kapasite analizleri devletlerarası ilişkileri anlamamızda bize analitik bir bakış açısı kazandırmakta ve kıyas yapmamıza yardımcı olmaktadır. Nitekim bu çalışmada kapasite analizlerinin günümüze kadar ulaştığı boyut incelenmiş ve Türkiye ya da Güney Afrika devletlerinden hangisinin gruba katılması durumunda daha faydalı bir etkileşim olacağı devletlerin siyasi öncelikleri ile beraber değerlendirilmiştir.

This paper explains an implementation model for a new method for Production Leveling designed for batch production system. The main structure of this model is grounded on three constructs: traditional framework for Operations Planning, Lean Manufacturing concepts for Production Leveling and case study guidelines. By combining the first and second construct, a framework for Production Leveling has been developed for

Satellite formation flying is an essential capability for many space missions that allow several closely spaced smaller satellites to be deployed. Depending on mission requirements, the ground receive station may carry several antennas and receive signal from each of the satellites in order to increase capacity and QoS. In this paper, we proposed an improved cluster based distributed MIMO channel model based on MIMO models for terrestrial communications in the WINNER/3GPP project. Simulations were also performed to evaluate the capacity of formation flying satellite systems  with different configurations using the proposed model and comparisons were made with the single satellite-single receive station system using capacity ratio and capacity difference as metrics. Our results show the effects of several factors such as type of formation, number of satellites, number of receive antennas, and SNR on capacity for the single satellite and multi-satellite systems.

In this paper, opportunistic cooperative amplify-and-forward networks in conjunction with three different adaptive policies, namely optimal simultaneous power and rate adaptation (OPRA), constant power with optimal rate adaptation (OPA) and truncated channel inversion with fixed rate (TIFR), are investigated and compared in terms of Rayleigh channel capacity where the source adapts its rate and/or power level according to channel conditions while the best relay simply amplifies and then forwards the received signals. Furthermore, the effect of diversity combining on the network is studied by investigating two cases of maximal ratio combining (MRC) and selection combining (SC) equipped at the destination. To this end, the mathematically tractable form of the upper and lower bound of the end-to-end effective signal-to-noise ratio (SNR) is provided and then used to derive the closed-form expression of the Shannon capacity. Our results are verified through comparison with Monte Carlo simulations in some representative scenarios where we also illustrate that, among them, for an arbitrary number of cooperative relays, OPRA slightly outperforms ORA, which, in turn, outperforms TIFR.

Capacity at unsignalized intersections are measured with various approaches called as deterministic and probabilistic approaches. Gap acceptance procedure (GAP) is mainly used in United States and several European countries. This method is based on critical gap acceptance and follow up times of vehicles from the minor road. The second method is empirical regression approach which its application is mainly based on research investigation from British research result (Kimber and Coombe, 1980). This method is developed by a large number of measurement field data in modern British streets. New approach called conflict technique which is based on pragmatically simplified concept where interaction and impact between flows at intersection is brought through mathematically formulated. Indonesia Highway Capacity Manual-1997 (IHCM-1997) is one of an example of using the empirical approach, however, due to current behaviour, e.q. no gap acceptance behaviour, unmotorized attendance with 13 clas...

Abstract. A High Data Rate (HDR) system has been proposed for providing downlink wireless packet service by using a channel-aware scheduling algorithm to transmit to users in a time-division multiplexed manner. In this paper, we propose using multiple antennas at the transmitter ...

This paper compares safety of automated and manual highway systems with respect to resulting rear-end collision frequency and severity. Safety is related to driver, vehicle and highway operating characteristics. Our safety analysis method maps the variation in these operating characteristics, modeled by probability distributions, to the probability and severity of the first rear-end crash due to a hard braking disturbance on the highway. The results show that automated driving is safer than the most alert manual drivers, at similar speeds and capacities. We also present a detailed safety-capacity trade-off study for four different automated highway system concepts that differ in their information structure and separation policy. This study quantifies the impact of inter-vehicle cooperation and operating speed of the Automated Highway System (AHS). It also compares and contrasts the safety characteristics of individual vehicle and platoon based Automated Highway Systems.

In this paper, cognitive transmission under quality-of-service (QoS) constraints is studied. In the cognitive radio channel model, it is assumed that the secondary transmitter sends the data at two different fixed rates and power levels, depending on the activity of the primary users, which is determined by channel sensing performed by the secondary users. A state transition model with eight states is constructed to model this cognitive transmission channel. Statistical limitations on the buffer lengths are imposed to take into account the QoS constraints. The maximum throughput under these statistical QoS constraints is identified by finding the effective capacity of the cognitive radio channel. The impact upon the effective capacity of several system parameters, including channel sensing duration, detection threshold, detection and false alarm probabilities, QoS parameters, and fixed transmission rates is investigated. It is noted that the optimal transmission rates are independent of the primary users' activity in the case of perfect channel sensing.

This paper studies the operational logic in an inter-bay automated material handling system (AMHS) in semiconductor wafer fabrication. This system consists of stockers located in a two-floor layout. Automated moving devices transfer lots between stockers within the same floor (intra-floor lot transfer) or between different floors (inter-floor lot transfer). Intra-floor lot-transferring transports use a two-rail one-directional system, whereas inter-floor lot-transferring

Abstract: A new method of capacity analysis at unsignalized intersections has been developed in this study for Indonesia where the drivers' behavior, traffic composition, level of roadside activities are different from those in developed countries. Typical cities in ...

Most traffic delays in regional evacuations occur at intersections. Lane-based routing is one strategy for reducing these delays. This paper presents a network flow model for identifying optimal lane-based evacuation routing plans in a complex road network. The model is an integer extension of the minimum-cost flow problem. It can be used to generate routing plans that trade total vehicle travel-distance against merging, while preventing traffic crossing-conflicts at intersections. A mixed-integer programming solver is used to derive optimal routing plans for a sample network. Manual capacity analysis and microscopic traffic simulation are used to compare the relative efficiency of the plans. An application is presented for Salt Lake City, Utah.