Application Note: HFAN-9.0.3 Rev.1; 04/08 APON Class A, B, & C Physical Layer Requirements Functional Diagrams Pin Configurations appear at end of data sheet. Functional Diagrams continued at end of data sheet. UCSP is a trademark of Maxim Integrated Products, Inc. LE AVAILAB APON Class A, B, & C Physical Layer Requirements 1 Introduction includes passive optical splitters. A Passive Optical Network (PON), is a cost effective network topology, that addresses the last mile of the communication infrastructure connecting the central office (CO) to the business or residential customer. 2 Passive Optical Elements ITU-T recommendation, G983.1 defines three classes of performance for APON (ATM-PON) systems. The three classes are to address different range requirements. This would enable tradeoffs between cost and reach, and consequently, operators could offer cost-effective solutions based on specific customer requirements. This note summarizes the requirements of various classes. Fig (1) shows the main elements of a PON system. The ODN normally consists of the following passive optical elements: ♦ ♦ ♦ ♦ ♦ Single mode optical fibers Optical connectors Passive branching components Passive optical attenuators Splices The optical path losses are associated with the above elements. Table (1) defines the optical path loss for the three classes of APON system. In general the optical distribution network (ODN) constitutes the optical transmission media for the connection of OLT to the ONUs, and typically R/S ONU #1 S/R Upstream Or ODN OLT R/S Downstream ONU #N Or OLT: ODN: ONU: R/S: S/R: Ol Optical line terminating, normally resides in CO Optical distribution network Optical network unit, resides normally in customer premises Reference point for measurement of optical parameters, ONU side Reference point for measurement of optical parameters, OLT side Figure 1. Architecture of the PON system Table 1. Classes of Optical Path Loss Application Note HFAN-9.0.3 (Rev.1; 04/08) Maxim Integrated Page 2 of 4 Class A (Note 1) Class B Class C Minimum loss 5dB 10dB 15dB Maximum loss 20dB 25dB 30dB Up to 8 Up to 16 Up to 32 Maximum No. of ONUs per OLT, (Note 2) Note 1. Class A only addresses systems operating at 622Mbps (G983.1). Note 2. A 20km maximum range is assumed. 3 Optical Interface Parameters The following tables define the optical interface parameters associated with the three classes of ODN. Table 2. Parameters for 155Mbps Both Downstream and Upstream Single Fiber Items Dual Fiber Class B Class C Class B Class C Mean Launch Power, Min -4dBm -2dBm -4dBm -2dBm Mean Launch Power, Max +2dBm +4dBm +1dBm +3dBm Worst case sensitivity -30dBm -33dBm -30dBm -33dBm Minimum overload -8dBm -11dBm -9dBm -12dBm Table 3. Parameters for 622Mbps Downstream Direction Single Fiber Items Dual Fiber Class A Class B Class C Class A Class B Class C Mean Launch Power, Min -7dBm -2dBm -2dBm -7dBm -2dBm -2dBm Mean Launch Power, Max -1dBm +4dBm +4dBm -2dBm +3dBm +3dBm Worst case sensitivity -28dBm -28dBm -33dBm -28dBm -28dBm -33dBm Minimum overload -6dBm -6dBm -11dBm -7dBm -7dBm -12dBm Table 4. Parameters for 622Mbps Upstream Direction Application Note HFAN-9.0.3 (Rev.1; 04/08) Maxim Integrated Page 3 of 4 Both Single Fiber & Dual Fiber Items Class A Class B Class C (Note 1) Mean Launch Power, Min -6dBm -1dBm -1dBm Mean Launch Power, Max -1dBm +4dBm +4dBm Worst case sensitivity -27dBm -27dBm -32dBm Minimum overload -6dBm -6dBm -11dBm Note 1. The upstream class C values are best estimates and may change in the future. Application Note HFAN-9.0.3 (Rev.1; 04/08) Maxim Integrated Page 4 of 4