When planning cellular networks, the goal is to position antennas and adjust their parameters to maximize the coverage and minimize the interference between antennas. In new generations of cellular networks like 5G, network planning is becoming critical due to the use of high frequencies and the densification of the network. Antenna locations are typically decided based on the availability of cellular towers, however, tunable parameters, like tilt and transmission power, determine the network capacity and the quality of service. To optimize the network and compute coverage and interference for different tilt and power values, radio propagation is simulated using ray tracing over a geospatial model of the environment. In this paper, we present a ray-tracing module that computes long-distance effects of cellular transmissions, to accurately model interference between remote antennas. The two main novelties are (1) the computation of diffraction to include non-line-of-sight propagation, and (2) parallel computation for efficiency and scalability. The demonstration presents the geospatial effect of diffraction on the computation and the use of GPUs for scalability while avoiding race condition in the transformation from a polar coordinate system to a Cartesian representation.

Planning of cellular networks is a process in which network engineers select locations for the cellular antennas and adjust parameters like transmission frequency, transmission power and tilt. The goal of network planning is to provide cellular coverage in places that are populated while decreasing interference between nearby antennas. To compute the coverage and interference, a geospatial model of the environment is created and radio propagation models are used for simulating the propagation of the electromagnetic waves. In this paper, we demonstrate a ray tracing tool that we have developed for computation of radio propagation. The tool computes the radio propagation over a 3D model of the world and presents the result as a heat map, in real time. The two main novelties of the system are (1) the ability to play the radio propagation as a video, for analyzing the effect of obstacles on the signal strength in different locations, and (2) inverse ray tracing which finds for a given location the antennas whose transmission affects the cellular signal or the interference at that location.

The goal of this paper is to define a QoS engineering framework for the evolving next-generation-Internet (NGI) platform. Note that specific algorithms for QoS provisioning in the Internet are at an early stage of development; hence much further analysis is needed before concrete solutions can be adopted. Our approach is therefore based on an effective adaptation of some basic notions from the telephony world, where quality of service provisioning has attained a state of maturity following a century of evolution. In particular, we identify some generic classes of traffic generated by various applications, and the functional modules required for providing QoS support. In regard to the latter, we identify the general methodologies that may be used for implementing the QoS functional modules, and further discuss some new approaches that need further research. Finally, we outline the manner in which a few candidate military applications may be supported over the proposed QoS framework.

Current standards reserve one bit in the ATM cell header to indicate loss priority. When congestion occurs at a queue lower priority cells can be discarded in order to insure a smaller cell loss rate for higher priority cells. Strategies for determining which cells to discard are termed space priority buffer management schemes. In this paper two adjustable space priority schemes are studied where a cell upon arriving to a full buffer can pushout a cell of opposite priority depending upon an adjustable parameter. A queueing analysis of an ATM switching node is conducted to compare the adjustable pushout schemes with other common space priority mechanisms.>

The notion of perceptible degradation of quality of the received signal seen by an individual user is introduced. It is proposed that the design of high-speed networks that support real-time traffic be carried out on the basis of a new performance measure, which is defined as the expected number of perceptible degradations that a customer is likely to encounter per unit of time. By using fluid-flow models, an analytical methodology is obtained for calculating the new performance measure. The method is illustrated by representative numerical examples from voice and video traffic for various link speeds and buffer sizes.>

For integrated networks that support circuit-switched traffic classes with varying bandwidth requirements, an efficient integration of the access control and routing functions is important in realizing optimum network performance. A hierarchical scheme for combined access control and routing is presented for realizing the above objective. The hierarchy comprises two levels; at the lower level each network node implements a distributed call routing strategy, while at the higher level a network supervisor implements an access control policy for minimizing the overall blocking probability. The access control problem to be solved at the supervisor level is formulated in an integer programming framework by a partitioning approach which divides the overall network into several distinct subnets, one corresponding to each bandwidth class. For routing the admitted calls within each subnet in an optimal fashion, a distributed minimum loss routing scheme is developed for implementation at the network nodes. Performance evaluation studies showing the superiority of the various control functions developed are presented.>

A novel multiplexing scheme for integrated networks characterized by the coexistence of circuit-switched and packet-switched traffic is described. The new scheme is realized by reinforcement of the basic movable boundary hybrid-switching technique by incorporating a packet queue-size dependent adaptive TASI (time assigned speech interpolation) mechanism. A detailed queuing model representation of the multiplexer is given, and an analytical evaluation of several performance parameters of interest, such as the blocking probability of the packet-switched subsystem, the freezeout probability of the circuit-switched subsystem, and the expected number of packets in the packet queue, is conducted. The results of some numerical studies are presented to illustrate the multiplexer performance under different conditions. Of particular significance is the tradeoff between the freezeout probability performance of the circuit-switched subsystem and the packet blocking performance of the packet-switched subsystem, which could be exploited in a systematic design of the integrated multiplexing scheme for specific applications.>