Error performance and availability objectives for hypothetical reference digital sections forming part or all of the medium-grade portion of an ISDN connection at a bit rate below the primary rate utilizing digital radio-relay systems
使用数字无线电中继系统 以低于主要速率的比特率 构成ISDN连接的部分或全部中级部分的假设参考数字部分的错误性能和可用性目标