Packet radio performance of inhibit sense multiple access withcapture

Current portable and land-mobile radio systems employ frequency modulation which exhibits a distinct capture effect. Furthermore, multipath propagation, shadowing, and the spatial distribution of the terminal units create data packets with varying signal strength. We investigate the performance of nonpersistent inhibit sense multiple access (ISMA) applied to the forward channel of packet radio communication networks. We show that the aggregate capacity of ISMA substantially increases compared to the noncapture case for small capture ratios. The mean packet delay of ISMA is also reduced with capture. The effect of different signal strength distribution is explored, and the capacity and delay improvements discussed     

A distributed access algorithm for cellular radio systems withchannel partitioning

Previous results in distributed power control and distributed channel access have demonstrated the possibility of high-capacity cellular radio networks without central control. However, these distributed algorithms may not converge completely in practical systems where the rate of channel variation (due to mobility, handoff, or interfering users entering or leaving the channel) approaches the rate at which power levels can be accurately measured and adjusted. We propose a new channel partitioning technique in which both dynamically allocated and fixed assignment channels are employed. This technique enables rapid distributed access that is inherently fair. Simulation results indicate that it is robust in responding to user mobility and handoff while yielding significant capacity gains over traditional fixed assignment systems     

Packet reservation multiple access for local wirelesscommunications

Simulation work is reported indicating that packet reservation multiple access (PRMA) allows a variety of information sources to share the same wireless access channel. Some of the sources, such as speech terminals, are classified as periodic and others, such as signaling, are classified as random. Packets from all sources contend for access to channel time slots. When a periodic information terminal succeeds in gaining access, it reserves subsequent time slots for uncontested transmission. Both computer simulations and a listening test reveal that PRMA achieves a promising combination of voice quality and bandwidth efficiency     

Packet radio in a Rayleigh channel

Statistical multiple access is analysed for a number of independent transmitter-receiver pairs exchanging data packets over a shared mobile-radio channel. Rayleigh fading `softens? the channel, resulting in less packet contentions and higher traffic capacity than for the standard Aloha channel.     

Packet reservation multiple access for wireless multimedia communications

Packet reservation multiple access (PRMA) is portrayed as a multimedia packet multiplexer conveying speech, data and video signals, which ensures that the slot occupancy of conventional time division multiple access (TDMA) links is approximately doubled. In addition to 20 speech users the 20 slot 720 kbit/s scheme presented supported 20 data users and up to seven video users, while maintaining a slot occupancy in excess of 80%.<>     

Resource allocation for cellular radio systems

High terminal traffic densities are expected in urban multiuser radio systems. An efficient allocation of resources is the key to high system capacity. In this paper, a distributed dynamic resource allocation (DDRA) scheme based on local signal and interference measurements is proposed for multiuser radio networks. It offers “soft capacity” for time division multiple access (TDMA) and frequency division multiple access (FDMA) systems, bounded above by N per base station, where N is the total number of channels in the system. The decisions are made local to a terminal and its base and are essentially independent of the rest of the system. A distributed dynamic channel assignment scheme is used to assign channels to new calls. This scheme assigns a channel that offers the maximum carrier to interference ratio (CIR) to a new call. A distributed constrained power control (DCPC) scheme based on CIR measurements is used for power control. The channel assignment scheme and the power control scheme are coupled to obtain an interactive resource allocation scheme. We compare the capacity of a system which uses the distributed dynamic resource allocation scheme described above with the capacity of a system which uses the channel assignment scheme alone. The system capacity is measured by simulation as the number of terminals that can be served by the system with a CIR above an acceptable minimum. In a 1D cellular system, coupling the channel assignment scheme with power control is discussed. Simulations were also used to show the effect of varying the maximum transmitter power on system capacity     

Channel coding strategies for cellular radio

To improve re-use of time/frequency slots in a cellular radio system, it is desirable for the average interference levels seen by all users to be made approximately equal. The authors provide constructions based on orthogonal latin squares that guarantee different sets of users will interfere in successive slots. When signal to interference ratios are independent from successive symbols, channel codes can provide a large diversity gain which is far in excess of the gain against additive noise. Consequently, coding with interleaving fits together very naturally with this construction. The authors illustrate how to achieve large performance improvement using convolutional codes with low decoding delay in a slow hopped system     

Beamforming for heterogeneous cloud radio access network

To overcome the problem that previous researches for heterogeneous cloud radio access network (H-CRAN) mainly focus on single macro cell,and only considered the intracell interference in the one macro cell,while the inter cell interferences among different macro cells are neglected,H-CRAN with multiple macro-cells was studied,and the objective was to maximize system sum-rate through jointly optimizing the beamforming vectors of macro base stations (MBS) and remote radio heads (RRH).Based on alternating optimization and Lagrangian dual method,a joint MBS and RRH beamforming algorithm was proposed.The original problem was first divided into two subproblems.Then,the two sub-problem were solved alternately to obtain the final solutions of the original problem.In addition,the closed expression solutions of the two sub-problem were derived based on Lagrangian dual method.The proposed algorithm was compared with some beamforming algorithms in the simulation.The experimental results demonstrate the proposed algorithm has a better performance in improving the sum-rate of H-CRAN.     

Intelligent framework for radio access network design

Wireless Networks - The evolution of 5G networks over the last few years has introduced a variety of technologies for more efficient radio access networks (RANs), which end up in ultra-dense...     

Deterministic access protocols for packet radio networks

In this paper, multiple-phase deterministic protocols for packet radio networks are introduced and analysed. Two modes of information transfer are considered, namely (a) broadcasting and (b) point-to-point transmission. We explore systematic ways of designing multiple-phase protocols and apply them on Manhattan networks. The proposed protocols are studied primarily from the point of view of throughput efficiency. Delay analysis is also presented.     

An architecture for next-generation radio access networks

With fourth-generation wireless technologies envisioned to provide high bandwidth for content-rich multimedia applications, next-generation mobile communication systems are well poised to lead the technology march. Incumbent with the new technology is the challenge of providing flexible, reconfigurable architectures capable of catering to the dynamics of the network, while providing cost-effective solutions for service providers. In this article we focus on IP-based radio access network architectures for next-generation mobile systems. We provide an insight into wireless mesh-based connectivity for the RAN network elements - using short high-bandwidth links to interconnect the network entities in a multihop mesh network for backhauling traffic to the core. A generic self-similar fractal topology, using optical wireless transmission technology, is described. We study the performance of the architecture and conclude that mesh-based architectures are well suited to provide highly scalable, dynamic radio access networks with carrier-class features at significantly low system costs.     

Uplink spectral efficiency of multicarrier joint detection codedivision multiple access based cellular radio systems

The uplink spectral efficiency of multicarrier joint detection code division multiple access (MC/JD-CDMA) based cellular radio systems is determined in a macrocellular environment. Results are presented for two different slow power control schemes and speech transmission at 8 kbit/s per mobile. Cellular networks with a cluster order of three to four facilitate a most favourable performance     

蜂窝网上的分组数据交换

蜂窝数字分组数据（ＣＤＰＤ）是一种在窝电话网（如ＡＭＰＳ）的频谱上使用的移动分组数据技术。ＣＤＰＤ的特点是可通过信道跳转利用蜂窝小区中的任何空闲信道,而不影响下层蜂窝系统的话音业务。本文概述了ＣＤＰＤ无线接口的主要功能层,分别介绍了物理层、数据链路层和相关子网汇聚协议的评义和功能特性,并强调了２个重要的方向－－媒质接入过程和信道跳转过程。     

Packet radio in the Amateur Satellite Service

A review of the satellite-based packet radio activities taking place in the Amateur Radio Service is presented. Five projects are discussed. The Digital Communications Experiment (DCE) on UoSAT-OSCAR-11 is a store-and-forward system that is accessed by a limited number of stations around the world designated as DCE gateways. These gateway stations retrieve and store messages forwarded to them via terrestrial packet radio networks. The Japanese FO-12 satellite is a store-and-forward system, and its user interface is much like computer bulletin boards accessed via land lines. It is available for use by all radio amateurs with the required equipment. Both UO-11 and FO-12 are in low earth orbits. The RUDAK experiment and the PACSAT project are also discussed     

Packet data transmission over mobile radio channels

Since in mobile radio Rayleigh fading poses the main threat to accurate data transmission, a mathematical model of the dynamics of Rayleigh fading is used to explore the optimum duration of data packets. The performance criterion is the rate of information transfer through the mobile radio channel. In addition to packet size, the information rate depends on: the speed of the mobile terminal, the channel bit rate, the size of the packet header, and the fade margin of the modulation and coding techniques. In particular, attention is focused on line rates of 16 kb/s and 256 kb/s (which are representative of the rates proposed for digital mobile radio systems in North America and Europe, respectively). At 16 kb/s, the optimum packet size is approximately 17 B (8.5-ms duration). At 256 kb/s, maximum throughput occurs when the packet contains about 48 B (1.5-ms duration). The precise optimum depends on vehicle speed, header size, and fade margin. The optimum packets are considerably shorter than the 125-B packets customarily used in terrestrial and satellite systems     

Stochastic power control for cellular radio systems

For wireless communication systems, iterative power control algorithms have been proposed to minimize the transmitter power while maintaining reliable communication between mobiles and base stations. To derive deterministic convergence results, these algorithms require perfect measurements of one or more of the following parameters: (1) the mobile's signal-to-interference ratio (SIR) at the receiver; (2) the interference experienced by the mobile; and (3) the bit-error rate. However, these quantities are often difficult to measure and deterministic convergence results neglect the effect of stochastic measurements. We develop distributed iterative power control algorithms that use readily available measurements. Two classes of power control algorithms are proposed. Since the measurements are random, the proposed algorithms evolve stochastically and we define the convergence in terms of the mean-squared error (MSE) of the power vector from the optimal power vector that is the solution of a feasible deterministic power control problem. For the first class of power control algorithms using fixed step size sequences, we obtain finite lower and upper bounds for the MSE by appropriate selection of the step size. We also show that these bounds go to zero, implying convergence in the MSE sense, as the step size goes to zero. For the second class of power control algorithms, which are based on the stochastic approximations method and use time-varying step size sequences, we prove that the MSE goes to zero. Both classes of algorithms are distributed in the sense that each user needs only to know its own channel gain to its assigned base station and its own matched filter output at its assigned base station to update its power     

Downlink outage predictions for cellular radio systems

A general model for predicting downlink outage due to co-channel interference in cellular radio systems is presented. The model accounts for path loss, log-normal shadowing, Rayleigh fading, and vehicle velocity. The outage predictions are obtained by computer simulation. Various outage control techniques are evaluated, including cell sectoring, transmitter control, and hands-off. It is shown that down link power control is quite useful when hand-offs are used, and that shadowing can have a large effect on the outage predictions. The outage predictions are applied to a digital cellular system that uses quadrature differential phase shift keying (QDPSK) modulation and Reed-Solomon (RS) coding. It is shown that the performance of a coded digital cellular system is largely limited by rapidly moving vehicles     

UK cellular radio developments

The spectacular development of cellular technology in the UK is briefly reviewed and some of the less obvious developments required to cope with market demand and a multiswitch network are described. These have resulted in the UK having two of the largest mobile networks in the world today, using some advanced techniques which will be applied more universally in the pan-European digital cellular system planned to open in 1991