Number Of Simultaneous Connections Research Articles

Spectrally Efficient UAV Communications using Non-Orthogonal Multiple Access (NOMA)

Non-orthogonal multiple access (NOMA) scheme with its share of benefits such as spectral efficiency and simultaneous support of massive connectivity, is one of the keys enabling technologies for upcoming 5G. However, in the context of UAV-assisted communication, existing literature mainly focuses on conventional orthogonal multiple access (OMA) which limits the spectral efficiency and number of simultaneous connections. Existing technologies are using LTE that only can serve 1 user per resource block. The user capacity nowadays is increased, so the existing technologies should be improved to higher user capacity such as 4 users per resource block. This research project focuses on the design of NOMA scheme for multiple users aiming to maximize the system capacity and spectral efficiency of Unmanned Aerial Vehicle (UAV) hotspot with baseline model and to simultaneously support mobile users. The proposed NOMA multi-users model is then compared with baseline model of 2 users per resource block in NOMA and OMA. The proposed NOMA model increases spectral efficiency, higher throughput and improved user fairness. The project only focuses on downlink communication with stationary users. The parameters measured are Bit Error Rate, Sum Rate, and Spectral Efficiency that depend on power allocation, altitude of UAV, and distance between UAV and users. Based on the simulation results, NOMA which employs Fractional Transmit Power Allocation (FTPA) algorithm has better performance in terms of sum-rate and spectral efficiency compared to those of OMA by as much as 650%. Results are also presented for various NOMA power allocation algorithms.

Admission control for WiMAX networks

This paper introduces admission control policies for WiMAX networks, which aim to reach three main goals: restrict the number of simultaneous connections in the system so that the resources available for the uplink scheduler are sufficient to guarantee the quality-of-service requirements for each connection, support the service provider expectations by maximizing the revenue, and maximize user satisfaction by granting additional resources. The optimal solution to meet these goals is non-deterministic polynomial-time hard and therefore cannot be solved in acceptable polynomial time. For this reason, both optimal and polynomial time heuristic solutions are introduced. Simulation experiments are used to evaluate and compare the proposed policies. Copyright © 2012 John Wiley & Sons, Ltd.

Evaluation of performance enhancing proxies in internet over satellite

AbstractPerformance enhancing proxies (PEPs) are widely used to improve the performance of TCP over high delay‐bandwidth product links and links with high error probability. In this paper we analyse the performance of using TCP connection splitting in combination with web caching via traces obtained from a commercial satellite system. We examine the resulting performance gain under different scenarios, including the effect of caching, congestion, random loss and file sizes. We show, via analysing our measurements, that the performance gain from using splitting is highly sensitive to random losses and the number of simultaneous connections, and that such sensitivity is alleviated by caching. On the other hand, the use of a splitting proxy enhances the value of web caching in that cache hits result in much more significant performance improvement over cache misses when TCP splitting is used. We also compare the performance of using different versions of HTTP in such a system. Copyright © 2003 John Wiley & Sons, Ltd.

Traffic characteristics of a free access network with selective circuits: Influence on channel mismatch

When the blocking probability of the traffic between nodes is to be estimated in the free access network with selective circuits, the loss generated by the channel mismatch between the originating/terminating node and the circuit group must be considered. This paper proposes a method of estimating the mismatch probability, considering the properties of the free access network construction. The estimation method is proposed with the following features: (1) the effect of mismatch on the joint connection distribution for the circuit group and all nodes is considered; (2) the number of simultaneous connections and connection probability on more than one circuit is considered; and (3) the different mismatch probability is considered for each originating and terminating node pair. Based on the actual result of estimation, the effects of the network construction conditions (number of time slots, number of circuits, and the number of access devices) as well as the time-slot selection method in channel assignment are examined. The effect of the mismatch for the case of multitraffic is evaluated by traffic simulation. A method is proposed to improve the blocking probability for the high-speed calls, considering the mismatch condition. The effect also is evaluated by the traffic simulation.

Traffic studies in automatic-switchboard telephone systems

The paper describes a telephone traffic recording machine by means of which not only the number of calls for a given period, but also the average duration of each call, is mechanically registered on a moving tape. The observations recorded here were taken on an automatic telephone system. The graphical record shows the exact duration of each connection, the number of connections made during a given interval, and the number of simultaneous connections in service at each instant. By means of these records it is possible to study the relative efficiency of small and large trunk groups, the average holding time of calls, and these observations permit the switches and trunks to be so arranged that the calls will be evenly distributed among the trunks in each group.

Traffic Studies in Automatic-Switchboard Telephone Systems

The paper describes a telephone traffic recording machine by means of which not only the number of calls for a given period., but also the average duration of each call, is mechanically registered on a moving tape. The observations recorded here were taken on an automatic telephone system. The graphical record shows the exact duration of each connection, the number of connections made during a given interval, and the number of simultaneous connections in service at each instant. By means of these records it is possible to study the relative efficiency of small and large trunk groups, the average holding time of calls, and these observations permit the switches and trunks to be so arranged that the calls will be evenly distributed among the trunks in each group.