通信专业毕业设计外文翻译---2g的潜力(编辑修改稿)

通信专业毕业设计外文翻译---2g的潜力(编辑修改稿)内容摘要：

ta in their many forms will bee more and more important. Voice will remain an important ponent in telemunications, but quite often it will be bined with other types of information to form multimedia applications. The current 2G works were designed to transfer voice traffic only。 realtime multimedia can be 共 8 页 第 5 页 transferred via the GSM phase2+ air interface only with great difficulty. GSM was designed at the end of the 1980s. The needs and expectations of the telemunication world then were totally different from those of today. Furthermore, the GSM system has evolved over the years very successfully to meet the new incremental demands, it has some problems that make it difficult to use for the emerging 3G applications. The biggest problem is the relatively inflexible air interface. An application that generates bursty traffic with several multimedia ponents cannot be effectively handled in GSM. The GSM interface cannot handle highly variable bit rates. The same connection cannot transfer services with different quality requirements. Speech, video, and other forms of data are multiplexed into multimedia services. The offered bandwidth is rigid and cannot be dynamically allocated as needed. This makes the spectrum use inefficient. However, GSM technology is surely not at the end of its life. The enhancements to GSM, such as HSCSD, GRPS, and EDGE, has improved its capabilities considerably, and the result, , is quite capable of handling many of the same applications that 3G is designed to handle. However, GSM operators could also integrate some other radio access technologies into their works to boost data rates。 for example, WLAN systems can provide bit rates up to several tens of Mbps (100Mbps) in hot spots, which is much more than the standard UMTS can provide. 2. Mobile telemunication consumers The mobile munication consumer market in Nigeria can be divided into three segments: highend, middlelevel, and lowend [2]. The highend market includes businessmen, high ranking managers, field service engineers, and journalists who have the ability to pay and are frequently on the move and in great need of highquality munication. It also includes early adopters of new mobile services such as young IT professionals and university students and researchers. All of the highend users already have mobile phones and use them heavily. The middle level market includes salaried or retired people and other students. These are people in moderate need of munications with local mobility. This group of people does not have high purchasing power. Their spending on munication is less than N 1500 (US $13) per month. Although most middle level users have mobile phones, they use them only when it is necessary. The lowend market includes farmers, low ine workers and those who usually stay locally. Their spending on munications is less than N 580 (US $5) per。