1、QUESTION ITU-R 287/4*,*Technical and operational characteristics for packet networktransmission in mobile-satellite services(2002)The ITU Radiocommunication Assembly,consideringa) that recent progress of IP-based networks is so remarkable in almost every area oftelecommunications that some new appli
2、cations in mobile-satellite services (MSS) are also intendedfor packet data transmission, in particular Internet Protocol (IP) based networks in the MSS;b) that the studies for packet data transmission will contribute to the smooth introduction ofsuch new applications in MSS and will encourage devel
3、opment of new systems;c) that bearer circuit availability requirements may not be the same for different types anddirections of transmission;d) that packet data transmission techniques often attain high quality and reliability by takingadvantage of unique characteristics compared to others;e) that w
4、ith respect to packet data transmission, performance objectives may be less stringentif it ensures the high quality and reliability with its error control and retransmission by high levelprotocols;f) that transmission characteristics, including not only the physical layer of digital satellitelinks b
5、ut also higher layers containing error control and retransmission protocols, should beconsidered;g) that packet data transmission includes delay, delay variation and error sensitive traffic;h) that transmission models and performance objectives for packet data transmission areneeded in addition to t
6、hose for the existing fixed networks in G-series, I-series, X-series andY-series Recommendations of ITU-T;j) that availability of packet-switched systems may be discussed in a different way from thoseof circuit-switched systems;k) that transmission characteristics and performance objectives may be d
7、escribed in differentways for different types of transmission schemes for bearer circuits. For example, a dedicated onefor a single user and a shared one for multiple users are classified by the manner in which the timeslots are utilized;l) that efficient packet transmission is beneficial because sp
8、ectrum allocated to MSS islimited,_* This Question should be brought to the attention of ITU-T SGs 2, 12, 13, 17 (former SG 7) andITU-R WP 4B.* Former Question ITU-R 233/8.decides that the following Question should be studied1 What is an appropriate transmission model (or hypothetical reference conn
9、ection) to definetechnical and operational characteristics of packet data transmission in the MSS?2 What are the technical parameters which are suitable to characterize packet datatransmission, in particular in IP networks in MSS systems?3 What are the operational requirements specific to packet dat
10、a transmission, in particular inIP networks in MSS systems?4 What are suitable characteristics for packet data applications, in particular in IP networks inMSS systems?5 How can performance objectives, including availability requirements and QoS (Quality ofService), be defined for MSS systems?6 What are appropriate methodologies to derive them?further decides1 that the results of the above studies should be included in (a) Recommendation(s);2 that the above studies should be completed before 2005.
