摘要:

AbstractA multiaccess protocol suitable for packet satellite broadcast channels is introduced in this paper. The proposed protocol, called diversity reservation ALOHA (DRA) combines the essential features of announced retransmission random access (ARRA). diversity ALOHA, and a reservation scheme with a slotted ALOHA reservation channel to achieve the goals of improved delay‐throughput characteristics and high channel utilization. Two versions of DRA protocols are analyzed. In scheme 1, called DRA with reservation cleared (DRA‐RC), no global queue information is required for a user to access the channel. In this version, even a successful transmission of reservation requests will be cleared from the system if it causes overflow. The second scheme, called DRA with reservation delayed (DRA‐RD), establishes a global queue distributed at users' terminals, so that users with successful transmission of reservation requests are assured of access rights although transmission may be delayed to later fames. Important system performance measures, such as activity‐factor‐throughput characteristics, for DRA‐RC and DRA‐RD are compared with those of ARRA. Examples of numerical results show that with system parameters properly chosen, substantial increases in attainable channel utilization are possible. Furthermore, the use of diversity for reservation allows a smaller packet delay especially under light traffic conditions. The analysis is validated in light of the simul

ISSN:0737-2884    

DOI:10.1002/sat.4600100202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper calculates the response time of a VSAT network. The response time consists of network access time from VSAT terminals to the hub station, query waiting and processing time, plus response queueing and transmission delay. The calculation is first done for a VSAT network which only has a central hub. The work is then extended to a distributed environment in which regional hubs are assumed. In addition to mathematical derivations, numerical examples are given to demonstrate several interesting phenomena. Computer simulations are also provided to verify the validity of the derived results.

ISSN:0737-2884    

DOI:10.1002/sat.4600100203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMeasurements of slant‐path attenuation and crosspolar discrimination, obtained from four satellite measurement programmes carried out at the BT Laboratories, Martlesham Heath, England, are described. The measurements covered frequencies in the range 11.3 GHz to 30 GHz, path elevations ranging from 8.3° to 29.9°, and were made using both circularly and linearly polarized signals. Cumulative distributions, derived from the measured data, are extrapolated to frequencies of 12.5, 14.3, 19.8 and 29.7 GHz and then combined to give statistics for a database of more than 20 ye

ISSN:0737-2884    

DOI:10.1002/sat.4600100204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper presents two new open‐loop synchronization algorithms for computing the satellite position. One is based on a three‐rotational co‐ordinate transformation, the other is based on a numerical iteration method. A detailed comparison of these two algorithms with other available algorithms is given with respect to accuracy of the computed separation distances between ground stations and the satellite, sensitivity to measurement and implementation errors, computation speed, and implementation compl

ISSN:0737-2884    

DOI:10.1002/sat.4600100205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0737-2884    

DOI:10.1002/sat.4600100201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY