By definition, the term “mobile-radio communications” describes any radio communication link between two terminals of which one or both are in motion or halted at unspecified locations and of which one may actually be a fixed terminal such as a base station. This definition applies to both mobile-to-mobile and mobile-to-fixed radio communica- tion links. The mobile-to-mobile link could in fact consist of a mobile- to-fixed-to-mobile radio communication link.The term “mobile” applies to land vehicles, ships at sea, aircraft, and communications satellites. In tactical situations, mobile-radio systems may include any or all of these types of mobile terminals.
标签： Communications Engineering Mobile
上传时间： 2020-05-30
上传用户：shancjb
Mobile wireless communications are in constant evolution due to the continu- ously increasing requirements and expectations of both users and operators. Mass multimedia* services have been for a long time expected to generate a large amount of data traffic in future wireless networks [1]. Mass multimedia services are, by definition, purposed for many people. In general, it can be distinguished between the distribution of any popular content over a wide area and the distribu- tion of location-dependent information in highly populated areas. Representative examples include the delivery of live video streaming content (like sports compe- titions, concerts, or news) and file download (multimedia clips, digital newspa- pers, or software updates).
标签： Broadcasting Generation Mobile Next
上传时间： 2020-05-31
上传用户：shancjb
The first edition of this book was published in 1992. Nine years later it had become clear that a second edition was required because of the rapidly changing nature of telecommunication. In 1992, the Internet was in existence but it was not the household word that it is in the year 2001. Cellular telephones were also in use but they had not yet achieved the popularity that they enjoy today. In the current edition, Chapter 1 has been revised to include a section on the Internet. Chapter 10 is new and it covers the facsimile machine; I had overlooked this important tele- communication device in the first edition. Chapter 11 is also new and it describes the pager, the cordless telephone and the cellular telephone system. These are examples of a growing trend in telecommunications to go ‘‘wireless’’.
标签： Telecommunication Circuit Design 2nd
上传时间： 2020-06-01
上传用户：shancjb
Changes in telecommunications are impacting all types of user group, which include business users, traveling users, small and home offices, and residential users. The acceptance rate of telecom- munications and information services is accelerating significantly. Voice services needed approximately 50 years to reach a very high teledensity; television needed just 15 years to change the culture and lives of many families; the Internet and its related services have been penetrating and changing business practices and private com- munications over the last 2 to 3 years.
标签： Telecommunications Handbook The
上传时间： 2020-06-01
上传用户：shancjb
Wireless communications has become a field of enormous scientific and economic interest. Recent success stories include 2G and 3G cellular voice and data services (e.g., GSM and UMTS), wireless local area networks (WiFi/IEEE 802.11x), wireless broadband access (WiMAX/IEEE 802.16x), and digital broadcast systems (DVB, DAB, DRM). On the physical layer side, traditional designs typically assume that the radio channel remains constant for the duration of a data block. However, researchers and system designers are increasingly shifting their attention to channels that may vary within a block. In addition to time dispersion caused by multipath propagation, these rapidly time-varying channels feature frequency dispersion resulting from the Doppler effect. They are, thus, often referred to as being “doubly dispersive.”
标签： Time-Varying Channels
上传时间： 2020-06-01
上传用户：shancjb
District energy (DE) systems use central heating and/or cooling facilities to provide heating and/or cooling services for communities. The advantages of district energy over conventional heating and cooling include improved efficiency, reliability and safety, reduced environmental impact, and for many situations better economics. DE systems can be particularly beneficial when integrated with cogeneration plants for electricity and heat, i.e., with combined heat and power (CHP) plants. One of the main impediments to increased use of cogeneration-based district energy is a lack of understanding of the behavior of integrated forms of such systems. This book is aimed at providing information on district energy and cogeneration tech- nologies, as well as systems that combine them.
标签： Cogeneration District Systems Energy and
上传时间： 2020-06-07
上传用户：shancjb
Today, electric power transmission systems should face many demanding chal- lenges, which include balancing between reliability, economics, environmental, and other social objectives to optimize the grid assets and satisfy the growing electrical demand. Moreover, the operational environment of transmission systems is becoming increasingly rigorous due to continually evolving functions of interconnected power networks from operation jurisdiction to control responsibly – coupled with the rising demand and expectation for reliability.
标签： Monitoring Protection Wide Area
上传时间： 2020-06-07
上传用户：shancjb
Radio frequency identification (RFID) technology is witnessing a recent explosion of development in both industry and academia. A number of applications include supply chain management, electronic payments, RFID passports, environmental monitoring and control, office access control, intelligent labels, target detection and tracking, port management, food production control, animal identification, and so on. RFID is also an indispensable foundation to realize the pervasive computing paradigm—“Internet of things.” It is strongly believed that many more scenarios will be identified when the principles of RFID are thoroughly understood, cheap components available, and when RFID security is guaranteed.
标签： Architectures NETWORKS SENSOR RFID AND
上传时间： 2020-06-08
上传用户：shancjb
Software-defined radios (SDRs) have been around for more than a decade. The first complete Global Positioning System (GPS) implementation was described by Dennis Akos in 1997. Since then several research groups have presented their contributions. We therefore find it timely to publish an up-to-date text on the sub- ject and at the same time include Galileo, the forthcoming European satellite- based navigation system. Both GPS and Galileo belong to the category of Global Navigation Satellite Systems (GNSS).
标签： A_Software-Defined_GPS_and_Galile o_Receiver
上传时间： 2020-06-09
上传用户：shancjb
#include<stdio.h> #define TREEMAX 100 typedef struct BT { char data; BT *lchild; BT *rchild; }BT; BT *CreateTree(); void Preorder(BT *T); void Postorder(BT *T); void Inorder(BT *T); void Leafnum(BT *T); void Nodenum(BT *T); int TreeDepth(BT *T); int count=0; void main() { BT *T=NULL; char ch1,ch2,a; ch1='y'; while(ch1=='y'||ch1=='y') { printf("\n"); printf("\n\t\t 二叉树子系统"); printf("\n\t\t*****************************************"); printf("\n\t\t 1---------建二叉树 "); printf("\n\t\t 2---------先序遍历 "); printf("\n\t\t 3---------中序遍历 "); printf("\n\t\t 4---------后序遍历 "); printf("\n\t\t 5---------求叶子数 "); printf("\n\t\t 6---------求结点数 "); printf("\n\t\t 7---------求树深度 "); printf("\n\t\t 0---------返 回 "); printf("\n\t\t*****************************************"); printf("\n\t\t 请选择菜单号 （0--7）"); scanf("%c",&ch2); getchar(); printf("\n"); switch(ch2) { case'1': printf("\n\t\t请按先序序列输入二叉树的结点:\n"); printf("\n\t\t说明：输入结点（‘0’代表后继结点为空）后按回车。\n"); printf("\n\t\t请输入根结点:"); T=CreateTree(); printf("\n\t\t二叉树成功建立！\n");break; case'2': printf("\n\t\t该二叉树的先序遍历序列为:"); Preorder(T);break; case'3': printf("\n\t\t该二叉树的中序遍历序列为:"); Inorder(T);break; case'4': printf("\n\t\t该二叉树的后序遍历序列为:"); Postorder(T);break; case'5': count=0;Leafnum(T); printf("\n\t\t该二叉树有%d个叶子。\n",count);break; case'6': count=0;Nodenum(T); printf("\n\t\t该二叉树总共有%d个结点。\n",count);break; case'7': printf("\n\t\t该树的深度为:%d",TreeDepth(T)); break; case'0': ch1='n';break; default: printf("\n\t\t***请注意：输入有误！***"); } if(ch2!='0') { printf("\n\n\t\t按【Enter】键继续，按任意键返回主菜单！\n"); a=getchar(); if(a!='\xA') { getchar(); ch1='n'; } } } } BT *CreateTree() { BT *t; char x; scanf("%c",&x); getchar(); if(x=='0') t=NULL; else { t=new BT; t->data=x; printf("\n\t\t请输入%c结点的左子结点:",t->data); t->lchild=CreateTree(); printf("\n\t\t请输入%c结点的右子结点:",t->data); t->rchild=CreateTree(); } return t; } void Preorder(BT *T) { if(T) { printf("%3c",T->data); Preorder(T->lchild); Preorder(T->rchild); } } void Inorder(BT *T) { if(T) { Inorder(T->lchild); printf("%3c",T->data); Inorder(T->rchild); } } void Postorder(BT *T) { if(T) { Postorder(T->lchild); Postorder(T->rchild); printf("%3c",T->data); } } void Leafnum(BT *T) { if(T) { if(T->lchild==NULL&&T->rchild==NULL) count++; Leafnum(T->lchild); Leafnum(T->rchild); } } void Nodenum(BT *T) { if(T) { count++; Nodenum(T->lchild); Nodenum(T->rchild); } } int TreeDepth(BT *T) { int ldep,rdep; if(T==NULL) return 0; else { ldep=TreeDepth(T->lchild); rdep=TreeDepth(T->rchild); if(ldep>rdep) return ldep+1; else return rdep+1; } }
上传时间： 2020-06-11
上传用户：ccccy
