WaveLink-SDH PRODUCT INTRODUCTION System Overview The Product comprises Indoor Units (IDUs) and Outdoor Units (ODUs) that together form the basis for an SDH fixed-wireless point-to-point microwave radio system. The system transports an STM-1 signal over the following frequency bands 1 : 7, 8, 11, 13, 15, and 18GHz. The radio system is composed of two terminals, one at each end of a radio link, where each terminal transmits to and receives from the other terminal. A terminal is composed of IDUs and ODUs (comprising the Product) as well as other, off-the-shelf accessories not supplied by ST Electronics (Satcom & Sensor Systems).. Terminal Configuration A terminal may be configured as follows: Protected terminal (1+1) configuration: consisting of two IDUs as well as two ODUs connected to their respective IDUs. The IDUs are interconnected via a Protection Cable that carries the electrical protected signals between them. There are four possible 1+1 configurations (refer to Sub-section 0). Unprotected terminal (1+0) configuration: IDU and its respective (one) ODU. consisting of only a single IDU Functional Description A block diagram of the Main IDU is illustrated in Figure 1: 1 Some of these bands shall be available in the future as part of the Product s roadmap. 1
STM-1 TX STM-1 RX SDH Interface SDH bytes SDH bytes Digital IF Coax to ODU Voice EOW Data EOW EOW Interfaces SDH Processor Modulator & Demodulator IF Cable Interface Wayside Wayside Interface Out-of-band traffic ODU C&M Q & F Interfaces CPU (Agent and Monitor&Control) Removable NVRAM Power to ODU Power Power Supply Figure 1: Block Diagram of Main IDU Power Supply Functionality and Specifications Power Supply Interfaces Power Supply Connector and Pin-Out The power supply connector is a 3-pin D-Type connector. Electrical Characteristics The Power Supply is compliant with ETSI EN 300 132-2. Operating Voltage The operating voltage ranges from 40.5V to 57V, as per ETSI EN 300 132-2 requirements. Inrush Current The IDU inrush current is compliant with EN 300 132-2, Section 4.7. Power Consumption The power consumption is as follows: Unprotected terminal: 65W Protected terminal: 130W 2
ODU Supply Short-Circuit Protection The ODU supply is protected using RCB (Recoverable Circuit Breaker) circuitry, with automatic recovery when the short-circuit condition disappears. The RCB is set to trip when current consumption exceeds approximately 2.5A. SDH Functionality and Specifications Interfaces There are two options for the STM-1 interface: Optical and Electrical.: Timing Under normal operating conditions, the IDU operates in through timing mode. In the presence of a LOS or LOF defect, the IDU will use its internal clock in order to generate (MS-AIS) SDH frame with valid timing. Internal Clock Frequency Accuracy The free-run accuracy of the internal clock is ±20ppm. Jitter Performance Jitter tolerance is in accordance with ITU-T G.825. Jitter generation is in accordance with ITU-T G. 813, Option 1. Jitter transfer is in accordance with ITU-T G.783, Type A. Maximum Input Frequency Offset The maximum frequency offset of the tributary input SDH signal is ±20ppm. Termination Overhead Byte Processing and Generation As an SDH regenerator, the terminal only processes RSOH bytes of the STM-1 frame. The multiplex section overhead bytes and the administrative unit pointers and payload are passed-through unaltered. summarizes the processing done on the RSOH bytes under normal operating conditions. For a case involving MS-AIS generation, refer to Sub-Section 0. 3
Defect(s) Detection The IDU detects the standard SDH defects relevant to SDH regenerator. LOS (detected only at the tributary port side of the system). LOF (detected on both the tributary and the radio ports). TIM - defined as a persistent mismatch between the expected J0 string (inserted by the user) and the received string, or a persistent J0 CRC-7 checksum mismatch. The IDU detects the TIM defect on both the tributary and radio ports. MS-AIS. MS-AIS Generation MS-AIS is generated downstream, when one or more of the following defects are detected: LOS, LOF or TIM. The IDU generates MS-AIS in accordance with ITU-T G.707 as all "1"s in the entire STM-1 frame, excluding the RSOH, before scrambling. Wayside Channel Functionality and Specifications The Wayside circuits provide an interface with, and perform processing for an additional payload (CEPT1: 2.048Mbps), which is multiplexed by the modem out-of-band, i.e., in addition to the STM-1 payload). Interface Connector The Wayside Channel Interface is provided via a Dual 1.0/2.3 type connector. Those connectors provide both transmission and reception functionality. Electrical Characteristics The Wayside Channel conforms with ITU-T G.703 as pertains to 2.048MHz-unbalanced signal. 4
Timing Timing Mode The timing of the incoming wayside payload is arbitrary and does not need to be synchronized in any way to the incoming SDH payload. On the transmit side, the wayside payload is adapted to internal clocks using a stuffing mechanism. On the receive side, the stuffing is extracted and a de-synchronizer is employed to recover the original wayside payload clock. Jitter Performance Jitter tolerance, jitter transfer and jitter generation all comply with ITU-T G.823. Maximum Input Frequency Offset The maximum frequency offset of the CEPT1 tributary input signal is ±50ppm. Internal Clock The Wayside internal clock is used during AIS transmission when the incoming signal is not valid for recovering its clock. The internal clock accuracy is better then 50ppm as specified in ITU-T G.703. Defect(s) Detection The IDU detects the following Wayside defects: LOS - detected when the incoming signal has "no transitions. The LOS defect is detected only on the tributary input to the IDU. LOF indicates that the demodulator cannot extract the wayside payload from the incoming data stream. AIS Generation The AIS signal is one in which all the information bits are replaced by 1. It is generated in the following cases: On the tributary to radio direction, when a LOS defect is detected. On the radio to tributary direction, when a WS Radio LOF defect is detected. 5
Voice EOW Functionality and Specifications The Voice EOW channel enables a user located at one site to communicate verbally with another user located at the other side of the radio link, by using a standard handset. Each terminal includes one port for handset connection to interface with the Voice EOW channel. The analog signal is converted to digital Pulse Code Modulation (PCM) format and is then transmitted over the IDU radio link through the SDH overhead E1 byte. Interface Voice EOW Ring Switch The Voice EOW ring switch, located on the front panel of the IDU, is used to indicate to the remote IDU a request for conversation (a buzzer sounds on both local and remote IDUs). This switch has two positions: RING user-selectable by momentarily toggling down. NORMAL default state automatic return from ring position. Voice EOW Handset Connector and Pin-Out The Voice EOW Handset Connector is a standard RJ45-type connector. Electrical Characteristics The following electrical characteristics apply to the Voice EOW Handset Connector: Input impedance to microphone signal: 1200 20% Microphone DC feeding (open circuit): 2.5V Input Voltage: AC-coupled Output impedance (to speaker): 150 20% Output voltage: AC-coupled Input/output level: 0dBm 3dB 6
Data EOW Functionality and Specifications The Data EOW channel enables a user located at one side of the radio link to send information to the other side via a channel implemented over the SDH overhead F1 byte using either the V.11 or G.703 interface. Electrical Characteristics Two different interfaces are provided (although only one may be used at any given time): G.703 complies with ITU-T G.703 for 64Kbps with co-directional timing. V.11 complies with ITU-T V.11 for 64Kbps with contra-directional timing. Modem Functionality and Specifications Modulation and Coding The modem uses 128QAM modulation concatenated with a Reed-Solomon code. Signal Acquisition The demodulator automatically detects whether or not it is locked on to a signal. When the demodulator is unlocked, it repeatedly executes an acquisition sequence in an attempt to lock. An indication is provided of the lock state of the demodulator. BER Estimation The modem is equipped with an accurate BER estimator: An updated current BER estimate is available every 1sec. The BER estimator operates in the range of 10-4 10-13. When the BER is outside this range, the estimator shows that the BER is either better than the lower range or worse than the upper range. IF Cable Interface Specification The IF Cable interface is used to connect the ODU to the IDU. This single coaxial interface combines the following signals in FDM: Modulator payload signal going to the ODU. Payload signal received at the ODU and intended for the demodulator. 7
Control and telemetry channel between the IDU and the ODU Power (DC) to the ODU. Interface IF Cable Connector The connector used for the IF cable is an N-type female connector. Electrical Characteristics The IF cable interface impedance is 50. Cable Length The maximum cable length depends on the type of cable used to connect the IDU to the ODU. For example, with RG-8, the cable may be up to 300m long. A quasi-static AGC circuit is employed to compensate for unknown IF cable lengths. ODU Specifications Interfaces IF Cable Interface Identical to the IDU s IF cable interface. Antenna Interface The antenna interface is given below for selected frequencies: Frequency 6/7/8/11GHz 13/15 GHz Flange N-type Female coax Proprietary Type connector RSSI Interface The RSSI connector is a BNC female connector. 8
The RSSI interface provides a voltage indicating the received signal strength. This indication is not very accurate (i.e., the output voltage is not calibrated as a function of the received signal strength), but it is monotonic: a weaker signal will always result in a lower voltage, and vice-versa. Consequently, the RSSI interface should not be used to obtain an absolute measurement of the received signal level; rather, it is intended as a relative indicator to assist antenna alignment. Electrical Specifications Frequency Bands The ODUs cover the following frequency bands 2 : 6GHz, 7GHz, 8GHz, 11GHz, 13GHz, 15GHz and 18GHz. Transmitter Output Power and Tolerance The maximum nominal output power (measured at the antenna port) is as follows: Frequency 6/7/8/11GHz 13/15 GHz Tx Power 21dBm 20dBm The tolerance of the output power is ±2dB of the nominal power and may be set in 1dB steps over a range 20dB. The accuracy of the output power indication is ±2dB. Transmitter Spectrum Mask Transmit spectrum mask for 128QAM complies with: ETSI EN 300 234 class 5 grade A, ETSI EN 300 430 class 5A and 5B. Receiver Maximum Input Signal Level The maximum receiver power level (BER=10-6 ) is -30dBm. Frequency Accuracy The ODU frequency accuracy is ±10ppm. This limit includes both short-term factors (environmental effects) and long-term ageing effects. The ODU center frequency resolution is 250KHz. 2 Some of these bands shall be available in the future as part of the Product s roadmap. 9
System Performance Sensitivity The system sensitivity is given in Table 1 for selected frequencies for BER=10-6 and BER=10-10. Table 1: System Sensitivity 6/7/8/11GHz 13/15 GHz BER 10-6 10-10 10-6 10-10 Threshold (dbm) -65.0-63.0-64.0-62.0 Residual BER The residual BER shall not exceed 10-13, when the following conditions are met: The received power is at least 10dB above the sensitivity specified for BER=10-6 (Sub-Section 0). There is no interfering signal (neither co-channel nor adjacent channel). Interference Immunity Co-Channel Interference The following limits of co-channel interference provide the maximum C/I values for 1dB and 3dB degradation of the 10-6 sensitivity specified in Sub-Section 0. Maximum C/I causing up to: 1dB degradation at BER=10-6 3dB degradation at BER=10-6 37dB 33dB Adjacent-Channel Interference The following limits of adjacent-channel interference provide the maximum C/I values (for like-modulated signals) for 1dB and 3dB degradation of the 10-6 sensitivity specified in Sub- Section 0. 10
Maximum C/I causing up to: 1dB degradation at BER=10-6 3dB degradation at BER=10-6 -3dB -7dB Distortion Sensitivity For a two-path propagation having a delay of 6.3ns, for BER of 10-6, the width of the signature shall not exceed ±22MHz relative to the assigned channel center frequency and the depth shall not be less than 12dB. Payload Delay The SDH payload delay caused by IDU and ODU processing, from the STM-1 input in the transmitting IDU to the STM-1 output at the receiving IDU, excluding any additional delay that may be induced by the IDU-ODU IF cables and radio wave propagation, is less than 350 s. Protection (1+1) Functionality and Specifications The protection capabilities in the 1+1 configurations are realized by routing payload between the two IDUs that make up the terminal. These IDUs are referred-to below as the Main IDU and the Protection IDU. While these two IDUs are identical in terms of hardware, their software behavior is different. Assigning a Main IDU software behavior or a Protection IDU software behavior is accomplished as part of the installation procedure. Protection Configurations There are four possible Protection configurations, as listed below: 1+1 HS-STI 1+1 FD-STI 1+1 HS-DTI 1+1 FD-DTI These configurations are actually various combinations of transmitter modes (Hot Standby HS, and Frequency Diversity FD) and tributary modes (Single Tributary Interface STI, and Dual Tributary Interface DTI) as described hereunder. 11
Protection Architecture Protection Interfaces In order to implement protection capabilities in the 1+1 configurations, payload is routed between the Main IDU and the Protection IDU by means of a Protection Cable. This Protection Cable termination is a SCSI-type connector. Payload Protection in the 1+1 Configuration The SDH signal may be physically connected to both IDUs (DTI), or to the Main IDU (STI) only. In STI: In the transmit direction, the SDH payload, after RSOH processing is permanently bridged, i.e., constantly connected to both modulators in both IDUs (and hence to both ODUs). In the receive direction, the SDH payload is extracted in both demodulators. Only the signal from the selected demodulator (depending on the protection switch position) is sent to the SDH interface on the Main IDU. In DTI: In the transmit direction, each IDU processes the SDH payload connected to it. Only the best-quality signal (after RSOH processing) is bridged to the two modulators in both IDUs (and hence to both ODUs). In the receive direction, the SDH payload is extracted in both demodulators. Only the signal from the selected demodulator (depending on the protection switch position) is sent to both SDH interfaces on the two IDUs. Protection Switches When the terminal is in Protection configuration, signal routing is a function of the Protection switches position. These switches are described below: 12
Tributary Switch controls routing in the transmit direction. In each IDU, it determines if the local modulator input will be taken from the IDU containing such modulator, or from the other IDU. In STI system configurations, the Switch position is always fixed to select the Main IDU payload, however, in DTI system configurations, the Switch position changes dynamically to select the best-quality payload. Demodulator Switch controls routing in the receive direction: it determines which demodulator output (Main IDU or Protection) will be routed to the payload interfaces on both IDUs. ODU Switch controls the ODU s mute function, i.e., determines if the ODU power amplifier is actually emitting energy. The Switch position changes dynamically only in the HS system configuration, in which only a single ODU is transmitting at any given moment. The IDU software automatically handles the positions of these switches. Switching Criteria The user can select one of two switching modes: Automatic and Manual. The following switching criteria are applicable to the Automatic mode. Switching Criteria for the Tributary Selection Switch The switching criteria for the Tributary Selection Switch are met when one or more of the following SDH defects are detected (refer to Sub-Section 0): SDH Tributary LOS, SDH Tributary LOF, SDH Tributary TIM, and MS-AIS Detect. Switching Criteria for the Demodulator Switch The switching criteria for the Demodulator Switch are met when one or more of the following alarms are activated: Demodulator early warning of SNR deterioration (used for hitless switching), Demodulator LOF, Demodulator BER alarm, Internal IDU alarms, and ODU internal alarm. Switching Criteria for the ODU Switch The switching criteria for the ODU Switch are met when one or more of the following alarms are activated: Internal IDU alarms, and ODU transmitter alarms. 13
Switch Positions in the Event of Significant Faults The switching procedure requires coordination among the Main IDU, the Protection IDU, and the ODUs connected to them. When this coordination cannot be established, due to an IDU communication failure, the following guidelines are followed. IDU Communication Failure: the switches freeze in their positions in both IDUs, and are prevented from moving. IDU Absent. If one of the IDUs (either main or protection IDUs) is either switched off or the connection cable is disconnected, the other unit recognizes this condition and moves its own switches so that the payload is routed through it only. Switching Performance Switching performance is specified as follows: Tributary protection switching is completed within 50 msec of detection of the alarm that initiated it. Demodulator protection switching is hitless (i.e., error-free) in the Main IDU, but takes 50 msec in the Protection IDU. This means that in STI protection configuration the switching is hitless, but in DTI protection configuration the outgoing tributary in the Main IDU will be error-free, while the outgoing tributary in the Protection IDU will have a limited burst of errors. ODU protection switching is completed within 100 msec from the time an alarm causing an ODU switch is detected, to the time the receiver has resynchronized. ATPC Functionality and Specifications Operational Concepts User-Set Administrative Limitation on Ptx Range The user may set an administrative limitation on the Ptx range ensuring that maximum transmitted power never exceeds a user-defined threshold. 14
Automatic and Manual Modes The ATPC function may be enabled or disabled by the user. Operation Under Fault Conditions If one or more of the following fault conditions prevails, the ODU at one side (the local side ) will transmit the highest available power: The IDU-ODU connection is lost at the remote (other) side. The SDH frame is not locked on the local side. Operation in 1+1 Protected Systems In 1+1 HS protection configuration, only one ATPC calculation is required for the active ODU (i.e., the one selected by the radio selection switch). In 1+1 FD protection configuration, two independent ATPC algorithms are active, one for each link. ATPC Specifications The ATPC specifications are as follows: Maximum supported link fading rate: 40dB/sec. Maximum tracking error under maximal fading rate: 5dB. Note: Due to the fact that the ATPC algorithm tracks receiver power, assuming a linear relationship between received power level and S/N ratio, it cannot handle interference-limited links, i.e., links where BER is induced as a result of an interfering signal rather than thermal noise. IDU Dimensions and Weight The IDU is comprised of a rack-mountable enclosure having a height of 1U (1.75 or 44.5mm). Dimensions The IDU dimensions are: 444.5mm (L) x 240mm (D) x 4.45mm (H). Weight The weight of an IDU is 4 kg. 15
ODU Dimensions and Weight Dimensions The ODU is cubical with a narrow profile. Its dimensions are: Height: 330mm (excluding the IF Cable Interface and RSSI Interface) Width: 224mm excluding the heat-sink fins and 274mm including the heatsink fins. Thickness: 65mm (excluding the Antenna interface) Note: ODUs for higher frequencies (13GHz and up) are slightly smaller. Weight The weight of an ODU is 6Kg. IDU Mechanical Installation The access to the system for interfacing and maintenance is only from the front, thus the IDU may be mounted in standard 19 or ETSI racks that are placed back-to-back and sideby-side. Rack Mounting The IDU may be mounted in both standard 19 and ETSI racks, using appropriate corner brackets. Grounding Grounding of the IDU is mandatory. A grounding screw is provided at the front of the IDU for connection to the rack ground. Ventilation Requirements The 1RU IDU does not make use of fans and is thermally cooled by natural convection. To allow ample room for the hot air to escape, the space above the IDU, to a height of 1RU, must be left vacant. For example, when installed in a rack, an empty 1RU slot must be reserved immediately 16
above the IDU. Environmental Specifications IDU Operation The IDU shall comply with climatic conditions for Class 3.2 (Partly temperature-controlled locations) requirements of ETSI ETS 300 019-1-3. Operation ambient temperature range: -5 to 45 C. ODU Operation The ODU shall comply with climatic conditions for Class 4.1 (Non-weather-protected locations) requirements of ETSI ETS 300 019-1-4. Operation ambient temperature range: -33 to 55 C. 17