A new modulation scheme for multitransmitter simulcast digital mobile radio communication

Many mobile radio communication systems require digital signaling simultaneously from multiple transmitters from the viewpoints of efficient frequency utilization and simplified receiver construction. A new modulation scheme intended to realize simulcast digital transmission is described. In this method, a modulation signal is made by superimposing a specific wave on an ordinary rectangular digital wave. The two conditions necessary for obtaining a diversity effect equivalent to the maximal-ratio combining are mathematically derived. The specific waves for the various transmitters may be sinusoidal waves having a frequency equal to the original bit rate, and phases which differ from one transmitter to another. In order to clarify the feasibility of this technique, experimental simulation tests have been performed in the 900-MHz band in a two-transmitter configuration. It is proved that this modulation scheme, in comparison with the carrier-frequency offset strategy, not only gives the same amount of improvement in digital signaling in an overlapped area, but also makes the allowable carrier frequency drift more than ten times larger.     

Addressing in radio paging

A technique of batching calls in radio paging reduces pager power consumption and increases performance with no increase in decoder complexity.     

Multiple radio zone plans in mobile radio systems

Multiple zone structure in a land mobile system seems to offer a flexibility in radio zone planning by using different interference distances conforming to the different system requirements in a system, thus improving the frequency utilization. A multiple zone structure can be formed by a tessellation of basic zone groups with an identical shape in parallel translation on a plane. To assure the possibility of the tessellation, two types of basic zone groups are investigated. One has several hexagonally shaped zones covered by an omnidirectional antenna beam from the zone center, while another is constructed as a subdivision of hexagons covered by a directive antenna beam. The former is expected to facilitate reduced interference distance between adjacent frequencies. An estimate of the latter type has shown better frequency economy than that in a conventional zone structure.     

Land mobile radio systems in Poland

The current situation of land mobile radio (LMR) systems in Poland is described. This includes paging, dispatch, trunking, and cellular systems. Frequency plan and organization of LMR communication in Poland are presented. Finally, the plan for the future development of LMR systems in Poland, prepared by the Ministry of Telecommunications, is summarized     

Adaptive paging schemes for group calls in mobile broadband cellular systems

In this paper, we analyze the problem of efficient paging for group call searches under realistic mobility patterns. Taking as a basis a location update scheme, based on the definition of an adaptive macro‐location area, adapted to the mobility pattern of the terminals, we characterize the residence probabilities in each location area of a generic macro‐area. With this information, we propose and evaluate different sequential group paging strategies, also taking into account their computational cost. Results show the suitability of some of the proposals (semiadaptive and hybrid schemes) and its applicability to new packet‐based broadband cellular systems. Copyright © 2010 John Wiley & Sons, Ltd.     

Capacity of cellular mobile radio systems

A lower bound to the Shannon capacity of the uplink channel of a cellular system, with perfect channel state information (CSI) at the receiver, is evaluated against the reuse distance and the level of shadowing affecting the interfering signals. Capacity is normalised to the covered area and expressed in bit/s/Hz/unit area     

Elements of cellular mobile radio systems

A major concern in a cellular mobile radio system is the co-channel interference. Therefore, the reduction of co-channel interference becomes a main thrust for the system design engineers. We use the co-channel interference reduction factor as a design criterion and predict the signal-to-interference (S/I) ratios in different system configurations. The handoff mechanism and algorithmic considerations, the traffic capacity and procedure for splitting cells, and the near-end-to-far-end ratio interference and reduction are the elements described.     

Digital signaling for radio paging

Some of the factors affecting the design of a binary signaling format for high capacity wide area digital radio paging are discussed. Topics considered are synchronization, battery economy techniques, error control coding to ensure acceptable success and false call rates, and the choice of bit rate. Paging successful and false call rates of typical format are predicted for moving and stationary pagers in environment of multipath propagation and shadowing.     

Doppler spread estimation in mobile radio systems

In this letter, Doppler spread estimation in digital mobile radio systems is described. A maximum-likelihood approach is derived, and used to develop suboptimal approaches with lower complexity. The proposed algorithms rely on periodic channel estimation and can be used in both TDMA and CDMA systems     

Vehicle location in cellular mobile radio systems

A tutorial discussion of vehicle location as used to control cellular mobile radio systems is presented. Early concepts and misconceptions concerning vehicle location are described, and the relation between location "accuracy" and system performance optimization is discussed. Measurement parameters commonly used for vehicle location are described, and considerations relating to the algorithm used in the location process are presented.     

Outage statistics in CDMA mobile radio systems

The statistics of the outage events in the reverse link of a direct sequence code-division multiple access (DS/CDMA) wireless system are investigated taking into account the effects of correlated Rician fading. The outage probability and the average fade duration are derived by assuming a constant multipath intensity profile, which includes a direct-path component in the first path. Simulations have been carried out which validate the analytical results     

Analysis of intelligent paging in personal communication systems

The authors quantify the paging cost for a specific form of intelligent paging in terms of the probability of a successful first paging step. When compared with the simultaneous and sequential paging schemes, the benefit of the intelligent scheme is found to be much more profound in pedestrian-dominated PCS environments     

跨省寻呼信号大"串连"

安徽省滁州市位于安徽省东部，比临江苏省的南京市和扬州市。 近几年来，由于寻呼发射机数量的不断增加，在108MHz167MHz频段，电磁环境比较复杂，用户投诉干扰的现象也时有发生。不久前，我市来安县公安局多次反应其无线调度通信网所用中转台频率（收158．625MHz／发164．325MHz）受不明信号干扰严重，无法使用，要求我站予以排查。干扰现象 接到申诉报告后，我们带着HP8920A综合测试仪，IC—R7000扫描接收机驱车赶到现场。在四楼机房，打开中转台的监听开关，听到的是一片寻呼编码基带信号的音调（码率为1200bps，同步码近似一60…     

Performance bounds of a multiple-step paging strategy in future universal mobile telecommunication systems

In future mobile telecommunications, due to the huge number of users and the specific functions that support mobility, a significant amount of signaling load will have to be carried by the finite capacity of the radio link. Hence, methods aiming at radio link signaling load reduction are welcome. In this paper we propose and analyze a method that saves paging signaling load by exploiting information related to the terminal location during the most recent interaction between the terminal and the network. The penalty paid is extra processing power and extra paging delays. An analytical model is developed so as to describe the performance versus traffic intensity and mobility conditions. The performance of the proposed paging scheme is investigated, and it is shown that the method operates well even in the worst case, which is the high user mobility conditions. Possible extensions of the method, which exploit information related to the mobility degree of each individual user or information characterizing the mobility conditions in a certain location area, are also proposed.This paper has been partially funded by CEC through the RACE 2066 Mobile Network (MONET) project. The paper does not present the views of the project as a whole, but those of the authors.     

Analysis of public safety traffic on trunked land mobile radio systems

Mobile radio systems for public safety and agencies engaged in emergency response and disaster recovery operations must support multicast voice traffic. In this paper, we analyze the distribution of call interarrival and call holding times for multicast voice (talk group) traffic on a transmission trunked mobile radio system. In such systems, the channel is held only while a user is making a call (while the push-to-talk key is pressed and the radio is transmitting). We find that the call interarrival time distributions are exponential and exhibit tendency toward long-range dependence. The call holding times best fit lognormal distributions and are not correlated. A potentially important implication of these findings is that performance estimation methods that assume memoryless Markov arrival and departure processes may not be viable approaches.     

Capacity estimation of cellular mobile radio systems

A capacity estimation procedure for cellular systems is introduced under a condition of concentrated traffic distribution. Comparisons are made of systems with 12.5 kHz and 25 kHz channel spacing to clarify the difference in system capacity for uniform and concentrated traffic distribution conditions. The results show it is necessary to take actual traffic distribution conditions into account in making system capacacity estimations.     

Outage possibilities in mobile radio systems suffering cochannelinterference

Mobile radio systems are usually designed on the basis of providing adequate reception quality to a specified area. The outage probability equations are used to determine the quality of radio reception when that quality is limited by a minimum required signal level, interference from a cochannel transmitter, and variability in the received signal levels. Considering Rayleigh fading and lognormal shadowing as joint causes of signal variation, average outage probability expressions are derived for mobile radio systems of a uniform nature. These expressions are used to investigate the influence of various system and propagation characteristics on reception quality     

Network planning for third-generation mobile radio systems

The success of UMTS relies not only on the development of a flexible air interface, efficient coding techniques, and handset technology; it is equally important to design a system that can support the underlying technology and to interface with other networks     

Causes of burst errors in multipath fading channel [mobile radio]

The so-called irreducible error due to frequency-selective fading is known to have a serious effect on mobile radio communication systems. Thus, the analysis of such errors is a prerequisite for making high-speed digital signal transmission over a fading channel feasible. The authors attempted to elucidate the physical mechanisms causing such errors using laboratory measurements of microscopic bit error rate. The results clarified some sources of burst errors in a multipath fading channel. In particular, large and rapid timing fluctuations of eye pattern due to severe delay distortion of the multipath channel was found to be the most dominant source of error