1 GSM Support NetPerformer System Reference
2 COPYRIGHTS AND DISCLAIMERS Published Date: March 2011 Document # 1614 This publication contains information proprietary and confidential to Memotec Inc. Any reproduction, disclosure or unauthorized use of this publication is expressly prohibited except as Memotec Inc. may otherwise authorize in writing. Memotec Inc. reserves the right to make changes without notice in product or component design as warranted by evolution in user needs or progress in engineering or manufacturing technology. Changes which affect the operation of the unit will be documented in the next revision of the manual. We have made every effort to ensure the accuracy of the information presented in our documentation. However, Memotec assumes no responsibility for the accuracy of the information published. Product documentation is subject to change without notice. Changes, if any, will be incorporated in new editions of these documents. Memotec may make improvements or changes in the products or programs described within the documents at any time without notice. Mention of products or services not manufactured or sold by Memotec is for informational purposes only and constitutes neither an endorsement nor a recommendation for such products or services. Memotec Inc. is a wholly owned subsidiary of Comtech EF Data Corp., and its parent company Comtech Telecommunications Corp (NASDAQ: CMTL). AccessView, CXTool, CX-U Series, CX-UA Series, AbisXpress, NetPerformer, AccessGate, ACTView, SDM- 8400, and the SDM-9000 series of products are either registered trademarks or trademarks of Memotec Inc.in Canada, the United States of America, and in other countries. Windows is a registered trademark of Microsoft Corporation in the United States and other countries. Any other trademarks are the property of their respective companies. Copyright 2011 Memotec Inc. Memotec Inc Henri Bourassa Blvd. West Montreal, Quebec Canada H4S 1P7 Tel.: (514) FAX: (514)
3 Contents Chapter 1: NetPerformer GSM Solution About the GSM Solution Network Compatibility GSM-only Network Mixed GSM and Non-GSM Network NetPerformer Solution for GSM Networks GSM Interfaces Supported GSM Traffic Types Supported Using NetPerformer on the GSM A/E Interface Advantages with NetPerformer Characteristics of GSM A and E NetPerformer Optimization of GSM A and E Using NetPerformer on the GSM Abis Interface Advantages with NetPerformer Network Connectivity Characteristics of GSM Abis NetPerformer Optimization of GSM Abis Using NetPerformer on the GSM Ater Interface Characteristics of GSM Ater NetPerformer Optimization of GSM Ater NetPerformer Platform for GSM Support Hardware and Base Software Requirements GSM Abis/Ater Licensed Software Option Satellite Network Application GSM 2/2.5G and 3G Convergence TDMoIP Application Configurable Software Features Chapter 2: Configuration Before You Configure Is the GSM Abis/Ater Option Already Installed? Configuration Procedure Configuring the NetPerformer for GSM Abis Configuring the NetPerformer for GSM Ater Memotec Inc.
4 2.2.3 Configuring the NetPerformer for TDMoIP Configuring the Digital Link Configuring a T1 Physical Port (LINK) Configuring an E1 Physical Port (LINK) Configuring the GSM Parameters Configuring an SS7 Signaling Channel Configuring the GSM PVCs Configuring the GSM Traffic Channels (CHANNEL) Configuring the Timeslot Subchannels Manually (TSSUB) Extended Parameters Chapter 3: Advanced GSM Applications Enhanced High-precision Clocking Activating the Enhanced Clock Activating the GPS Port About the Prioritization of GSM Traffic Uses and Benefits How It Works Satellite Backup E1 Standard Mode E1 Bypass Mode Configuration PVC Link Redundancy in a TDMoIP Application Configuration Example Chapter 4: Monitoring and Statistics About Monitoring and Statistics Display GSM Channels (DCH) Command Display GSM TS Channel Allocation (DTSCH) Command Display DSP Allocation (DDSP) Command Display Jitter Level (DJL) Command Display GPS Status (DGPS) Command Viewing the GPS Receiver and PLL Status GPS Status PLL Status Viewing the GPS Log Memotec Inc.
5 4.6.5 Viewing the GPS Version Display Counters (DC) Command GSM Traffic Counters Transmit and Receive Traffic Counters Display Errors (DE) Command Display States (DS) Command Monitoring Procedures Monitoring Activation of the Autodetection Function Monitoring 3G Support Deactivation PCM Raw Data Capture Error Log Chapter 5: Concepts and Terminology About GSM Mobile Cellular Systems Transmitter Frequencies Types of Cells Cells per Cluster GSM Network Architecture Mobile Station (MS) Base Station Subsystem (BSS) Network and Switching Subsystem (NSS) Operation and Support Subsystem (OSS) GSM Network Functions Transmission Radio Resources (RR) Mobility Management (MM) Communication Management (CM) Operation and Maintenance (O&M) GSM Radio Interface Access Schemes GSM Channels List of Acronyms Chapter 6: SE/GSM Configuration Parameters Jitter buffer (ms) Memotec Inc.
6 6. 2 Mode used when SIG detected Mode used when TCH detected Continuous AUTO detection Activate 3G support Call management timeout (s) Chapter 7: SE/SLOT/#/CHANNEL Configuration Parameters Channel Number Protocol Timeslot Location on the GSM network Vendor of the GSM units TS subchannel mode Subchannel speed mask Idle code Remote unit Remote port number Chapter 8: SE/PVC/#/GSM Configuration Parameters GSM traffic type Frame over IP, source Frame over IP, destination Frame over IP, port number Frame over IP, DSCP Use a forced route Port GSM maximum calls GSM VAD Deactivate threshold GSM VAD Activate threshold GSM VAD A (bps) GSM VAD B (bps) GSM VAD K (coefficient in percentage) GSM group Memotec Inc.
7 8. 15 GSM maximum frame size GSM pack delay (ms) PVCR PVC that manages this PVC Index Index-1 Memotec Inc.
8 Memotec Inc.
9 1 NetPerformer GSM Solution Memotec Inc. 1-1
10 GSM Solution 1.1 About the GSM Solution The NetPerformer solution optimizes 2/2.5G GSM Abis/Ater traffic, and bundles and transports GSM 3G UMTS traffic. It decodes GSM signaling information and voice timeslots according to ETSI standards. GSM 2/2.5G traffic is inherently bandwidth inefficient as it is based on a circuit-switched, TDM-based system. It requires a dedicated network of leased lines, fiber, microwave links and satellite links, which represent high recurrent costs. The system infrastructure is often insufficient or nonexistent, and services are often deployed in remote areas as an alternative to rural telephony. Satellite communication can be used in these cases, but is very costly. These problems are resolved with the addition of the NetPerformer to the GSM network. For all NetPerformer products: Support of GSM A and E is offered with the base software Support of GSM Abis and Ater is offered as a licensed software option. When this license is installed, the NetPerformer supports GSM Abis/Ater applications over E1/T1, serial (WAN) and IP (LAN) connections. NOTE: For the SDM-9210, the GSM Abis/Ater licensed software option may be bundled with the base product software on certain OEM models. 1-2 Memotec Inc.
11 NetPerformer GSM Solution 1.2 Network Compatibility GSM-only Network For GSM applications all NetPerformer units must be running the same phase of GSM. Backward compatibility is possible between V (R04 or later) and V GSM Abis/Ater support in V10.4.X is the only version that can run on the SDM If an SDM-9620 is installed in the network, all participating NetPerformer units must be upgraded to the same version of V10.4.X that is running on the SDM Refer to the NetPerformer Version V10.4.X Release Bulletin for upgrade procedures Mixed GSM and Non-GSM Network A NetPerformer unit installed with the GSM licensed software option can communicate with a unit that does not have the GSM license installed. This requires the following on all participating units: Installed with V R01 or later Configured for PowerCell voice transport method (PVCR) A PVCR connection must be configured between the unit running GSM and the unit without GSM. The non-gsm unit must be configured with the PowerCell version Global parameter set to 2. Memotec Inc. 1-3
12 GSM Solution 1.3 NetPerformer Solution for GSM Networks The NetPerformer can be installed at various points of the GSM network to optimize traffic and reduce the bandwidth load: Reduces operational costs by lowering bandwidth requirements on all GSM network interfaces Converts TDM data to Packet data Compresses signaling and O&M data, and suppresses redundant data. On the TCH stream: - Redundant data is removed - Silence and idles (flags) are not transmitted across the WAN Provides load balancing, which allows for multiple links to be set up between the same two units using serial or digital ports Supports integration of packetized voice (besides GSM), LAN routing, ATM traffic and legacy data NOTE: For WAN traffic, all participating NetPerformer units must be installed with the GSM Abis/Ater Option, as the PVCR protocol used with GSM is not compatible with the PVCR protocol used on the NetPerformer base product. Spoofs the SS7 protocol and optimizes the signaling channel by transmitting only significant data end-to-end Provides congestion control, prioritized flow control, packetization and call blocking to maximize the bandwidth Low end-to-end delay (maximum 20 to 30 ms) Autodetection of voice/data or signaling traffic on timeslot subchannels Supports IP multiplexing with GSM traffic Can be used in a point-to-multipoint application Optional high-precision clocking for synchronization and timing control of system clocks. See Enhanced High-precision Clocking on page 3-2 for details. 1-4 Memotec Inc.
13 NetPerformer GSM Solution The GSM network with NetPerformer is illustrated in Figure 1-1. Figure 1-1: GSM Network with NetPerformer GSM Interfaces Supported A and E interfaces: PCM voice is optimized using standard available codecs (G723, G726, G729, ACELP-CN). Available on all NetPerformer products. Refer to Using NetPerformer on the GSM A/E Interface on page 1-7 Abis interface: Coded TRAU bandwidth is optimized using various techniques. Available only on an SDM-9210, SDM-9220, SDM-9230, SDM-9606 or SDM installed with the GSM Abis/Ater licensed software option. Refer to Using NetPerformer on the GSM Abis Interface on page 1-10 Ater interface: Coded TRAU bandwidth is optimized, and SS7 messages are processed with either FISU spoofing or MTP2 layer termination (configurable). Available only on an SDM-9210, SDM-9220, SDM-9230, SDM-9606 or SDM installed with the GSM Abis/Ater licensed software option. Refer to Using NetPerformer on the GSM Ater Interface on page GSM Traffic Types Supported Signaling: 16K, 32K and 64K, both concentrated and non-concentrated Voice/fax: - Enhanced Full Rate (EFR) at 12.2K - Full Rate (FR) at 13.5K - Half Rate (HR) at 4.75K to 12.2K - Adaptive Multi Rate Full Rate (AMR-FR) at 4.75K to 12.2K Memotec Inc. 1-5
14 GSM Solution - Adaptive Multi Rate Half Rate (AMR-HR) at 4.75K to 7.4K GSM Data: - GPRS - EDGE - Extended Data - FR data - HR data - Frame Relay-based Gb Digital cross connect: 64 Kbps non-blocking, 8 Kbps subchanneling. For a detailed list of traffic types supported, turn to For each timeslot subchannel, the subchannel mode or type of traffic currently being carried by that timeslot subchannel is displayed beneath the applicable Bitn columns: on page 4-7. NOTE: The GSM PVC parameter GSM traffic type should be set to TCH for all of these traffic types. Refer to Configuring the GSM PVCs on page Memotec Inc.
15 NetPerformer GSM Solution 1.4 Using NetPerformer on the GSM A/E Interface This is a hub solution available on the NetPerformer base product (no license required). The NetPerformer units transporting GSM A traffic between the BSC and MSC, or E traffic between the MSC and PSTN, via digital E1/T1 links. For configuration details, refer to Configuring the NetPerformer for GSM A or E on page 2-4. Figure 1-2: The NetPerformer with GSM A Interface: between the BSC and MSC Figure 1-3: The NetPerformer with GSM E Interface: between the MSC and PSTN A and E traffic uses SS7 signaling, which is configured on one or more channels of the E1/T1 link with the SS7 or SS7MTP2 protocol. One or more voice channels are also required, using the G.711, ACELP-CN or other voice protocol Advantages with NetPerformer The NetPerformer transports the GSM A or E traffic point to point, and offers the following advantages: Multiple A/E interfaces can be concentrated over a single WAN connection WAN flexibility: satellite links, Frame Relay, ATM, IP backbone, leased lines, etc. Choice of physical interfaces: serial, digital E1/T1, Ethernet Redundant WAN links can be installed to improve overall network resilience Voice and data are integrated. Any bandwidth that is not used for GSM traffic can be used to carry data (IP or others), LAN and legacy data, or analog voice High bandwidth savings through voice compression of 64K PCM audio paths using a highly efficient voice codec (8:1 voice compression ratio, or as high as 20:1 when used with silence suppression) Data is also compressed, to improve the efficiency of the link. Memotec Inc. 1-7
16 GSM Solution Characteristics of GSM A and E 2 Mbps E1 or 1.54 Mbps T1 circuit Up to 30 voice channels per line SS7 signaling Voice channels are uncompressed: - Circuit switched, TDM-based - Bandwidth for inactive channels (unassigned timeslots) is wasted NetPerformer Optimization of GSM A and E The NetPerformer provides several optimization features: Signaling and O&M data are compressed, and transported transparently SS7 traffic is handled in one of two ways: - FISU spoofing (Protocol parameter set to SS7). Only significant data is transmitted end to end, and idles and redundant data are handled locally - MTP2 layer termination (Protocol parameter set to SS7MTP2). No FISU or LSSU frames are transported to the remote side. Basic ISUP support is also available for SS7 traffic, used for a DCME application only (Protocol parameter set to SS7 ISUP-A or SS7MTP2 ISUP-A). Voice optimization to conserve bandwidth: - Compression of 64K PCM audio paths using highly efficient voice codec (5.3K to 8K) - Silence suppression further reduces bandwidth requirements - Comfort Noise generation contributes to high voice quality Works on multiple types of WAN interfaces; - Not limited to digital E1/T1 interfaces - Can integrate other types of traffic with the required traffic prioritization levels. These features result in up to 90% bandwidth reduction on GSM A or E interfaces. For example, a single A/E interface with 30 voice calls can be optimized to less than 256 Kbps. Voice Channels Uncompressed Bandwidth Required (in Kbps) 8K Voice 8K Voice 40% Silence Table 1-1: Bandwidth reduction on GSM A or E interface 1-8 Memotec Inc.
17 NetPerformer GSM Solution Voice Channels Uncompressed Bandwidth Required (in Kbps) 8K Voice 8K Voice 40% Silence Table 1-1: Bandwidth reduction on GSM A or E interface Memotec Inc. 1-9
18 GSM Solution 1.5 Using NetPerformer on the GSM Abis Interface This solution connects multiple remote BTS sites to the BSC on the hub side, with the NetPerformer units connected to the BTS and BSC via digital E1/T1 links. Available only on an SDM-9210, SDM-9220, SDM-9230, SDM-9606 or SDM-9620 installed with the GSM Abis/Ater licensed software option. For configuration details refer to Configuring the NetPerformer for GSM Abis on page 2-5. Figure 1-4: The NetPerformer with GSM Abis Interface: between the BTS and BSC One NetPerformer unit is set up at the remote location, connected to the BTS via the digital E1/T1 link. The Location on the GSM network must be set to BTS ABIS (refer to Configuring the GSM Traffic Channels (CHANNEL) on page 2-16) The other NetPerformer is on the hub side, connected to the TRAU in front of the BSC. On this unit the Location on the GSM network must be set to BSC ABIS. One or more channels are configured with the GSM protocol (refer to Configuring the GSM Traffic Channels (CHANNEL) on page 2-16). These channels are divided into timeslot subchannels (or TSSUB), which are defined to support the type of traffic detected by the NetPerformer. For example, some are defined as traffic channels (TCHD or TCHU) for transporting voice and data, and others as control channels (SIG) for signaling and O&M functions. Refer to GSM Channels on page 5-11 for background information on GSM channels Advantages with NetPerformer Packet-based Abis transmission permits variable bandwidth for TDMA, which otherwise has a fixed-time allocation. With the addition of the NetPerformer: Signaling data is not a constant stream, and can be easily compressed Audio can be carried at a variable rate Idle traffic and silence are suppressed Traffic is allocated dynamically to all available channels Memotec Inc.
19 NetPerformer GSM Solution Network Connectivity The NetPerformer is connected to the BSC and BTS through its T1 or E1 interface cards It communicates with the network management system through IP connectivity The WAN connection can be a leased-line, wireless or shared packet network PVCs can also be used in a GSM-only application, using Frame Relay over IP (FRoIP). Redundant WAN links can be installed to improve overall network resilience The timeslot subchannels (TSSUB) defined on the NetPerformer CHANNEL support the individual TRXs. For GSM Abis, the timeslot subchannels can be defined automatically through the NetPerformer Autodetection function. To enable this function, refer to For an Abis application, set the GSM auto detect mode to: on page Characteristics of GSM Abis The most common interface in GSM networks 2 Mbps E1 or 1.54 Mbps T1 circuit Supports multiple radio channels per E1 or T1 line Voice channels are compressed: - Circuit switched, TDM-based, using 16-Kbps subchannels (8 for every pair of 64K timeslots). Maximum of 16 channels for Half Rate (HR) - Bandwidth for inactive channels is wasted Timeslot Allocation Each radio channel supports a maximum of 8 subchannels using 2 64-Kbps timeslots GSM signaling can be transported in the radio channel or a separate timeslot, at 16, 32 or 64 Kbps The E1 interface has 32 timeslots, and the T1 interface has 24 Each TDMA channel (tranceiver timeslot, or TRX) uses 2 timeslots All TRXs must be defined in contiguous timeslots A single 64-Kbps timeslot can be configured, or multiple subchannels of 8, 16, or 32 Kbps The O&M channel can also be 8, 16, 32 or 64K Signaling and O&M scenarios vary depending on the type of switch and the network topology. Possible scenarios include: - 32K signaling with one 32K O&M channel Memotec Inc. 1-11
20 GSM Solution - 16K signaling with several 16K O&M channels - 16K signaling with several 64K O&M channels - 64K signaling with one 64K O&M channel. An example of timeslot allocation is the following: Format of Transceiver Timeslots (TRXs) One TRX uses two 64K timeslots Each of the two timeslots is divided into subchannels, as follows: - At 16K (Full Rate): - At 8K (Half Rate): - At 16K/8K (Dual Rate): 1-12 Memotec Inc.
21 NetPerformer GSM Solution A particular subchannel can carry signaling or voice/data traffic The associated signaling channel can be assigned to a separate timeslot and operate at a different rate NetPerformer Optimization of GSM Abis Signaling traffic and OEM data are compressed: - Processed as voice/data traffic by the DSP, and multiplexed with voice packets during transmission - Fully supported in discrete 64K timeslots or subchannels at 8, 16 or 32K - Idles are removed - Bandwidth requirements are reduced. Audio data is optimized: - Packetized as transparent 64K PCM - The GSM Abis TCH stream is analyzed, removing unused and redundant bits using DSP processing power - Supports voice/data integration - NetPerformer recognizes when the TCH stream is carrying voice or data and optimizes it accordingly. Less bandwidth is required on data channel timeslots - Silence is not transmitted - NetPerformer can be configured to allocate a channel only when a call is established - Spoofing and suppression of idle voice channels (grooming) so that unused timeslots are not transmitted Not limited to digital E1/T1 interfaces: - Works on multiple types of WAN interfaces, including satellite, leased lines, Frame Relay, ATM, IP - Can integrate other types of traffic with the required prioritization levels. These features result in up to 50% bandwidth reduction on a GSM Abis interface, depending on the traffic pattern (type of vocoder, Full Rate or Half Rate, percentage and type of data traffic, silence ratio, number of idle channels). Please contact Memotec Inc. or your NetPerformer distributor for an evaluation of the potential bandwidth savings specific to your installation. Memotec Inc. 1-13
22 GSM Solution PowerCell Encapsulation of Abis Traffic The NetPerformer s unique PowerCell technology permits convergence of Abis traffic with other traffic types, and tunneling of Abis through any type of WAN network. Abis signaling and optimized cells from different TCHs are multiplexed and encapsulated as NetPerformer PowerCell frames The NetPerformer at the receiving end demultiplexes the PowerCell traffic and recreates the original Abis frames for each TCH. Figure 1-5: PowerCell Tunneling of Abis Traffic over Various WAN Networks The NetPerformer can transport PowerCell frames over any type of WAN network The result is a homogeneous logical network using PowerCell. Refer also to TDMoIP Application on page NOTE: When integrating with WAN traffic, all participating NetPerformer units must be installed with the GSM Abis/Ater Option, as the PVCR protocol used with GSM is not compatible with the PVCR protocol used on the NetPerformer base product. Dual Rate Traffic Channels A dual rate traffic channel (TCHD) initially operates at 16 Kbps. A volume threshold is defined on the GSM switch, above which the speed is reduced to 8 Kbps. If the BTS/BSC equipment switches from 16 Kbps to 8 Kbps, the NetPerformer processes the channel 1-14 Memotec Inc.
23 NetPerformer GSM Solution accordingly. A TCHD channel can carry one 16-Kbps voice call or, when the traffic volume increases, one or two 8-Kbps voice calls. This allows the provider to carry more voice calls without having to increase the number of subchannels (or TRXs). NOTE: Less bandwidth optimization is possible at 8 Kbps, since there is less GSM overhead that can be removed. Users may experience a change in voice quality on calls placed after the volume threshold has been reached. Example: A system with 10 TRXs can support 80 calls at 16 Kbps. The provider decides that when the volume of calls reaches 80%, all subsequent calls should be placed at 8 Kbps rather than 16 Kbps. This means that the first 64 calls will be placed using 16 Kbps, and the 65th call using 8 Kbps. All subsequent calls are placed at 8 Kbps until the maximum number of voice calls is reached. Using dual rate traffic channels (TCHD) this system can support 64 calls at 16 Kbps, plus 32 calls at 8 Kbps for a total of 96 calls. Memotec Inc. 1-15
24 GSM Solution 1.6 Using NetPerformer on the GSM Ater Interface This is a hub solution with the NetPerformer units connected to the BSC and the MSC via digital E1/T1 links. Available only on an SDM-9210, SDM-9220, SDM-9230, SDM or SDM-9620 installed with the GSM A-bis/ter licensed software option. For configuration details, refer to Configuring the NetPerformer for GSM Ater on page 2-6. Figure 1-6: The NetPerformer with GSM Ater Interface: between the BSC and MSC One NetPerformer unit is connected to the BSC at the remote location. The Location on the GSM network must be set to BSC ATER (refer to Configuring the GSM Traffic Channels (CHANNEL) on page 2-16) The other NetPerformer is the hub, connected to the TRAU in front of the MSC. On this unit the Location on the GSM network must be set to MSC ATER Ater traffic uses SS7 signaling, which is configured on one or more channels of the E1/T1 link using the SS7 or SS7MTP2 protocol One or more channels are also configured with the GSM protocol (refer to Configuring the GSM Traffic Channels (CHANNEL) on page 2-16). Unlike the Abis application, no signaling subchannels are required on these channels, which are all configured as traffic channels (TCHD or TCHU) for transporting voice and data. Refer to GSM Channels on page 5-11 for background information on GSM channels Characteristics of GSM Ater 2 Mbps E1 or 1.54 Mbps T1 circuit Typically 8 Full Rate voice channels for every two 64-Kbps timeslots SS7 signaling in 64 Kbps timeslots (similar to the A interface) Audio channels have the same compression options as Abis (TCH compression) The TRAU is in the MSC rather than the BSC Voice channels are compressed - Maximum of 120 voice channels per digital line (at 16 Kbps) - Circuit switched, TDM based - Uses 16-Kbps subchannels for Full Rate support (8 per two 64K timeslots) or 8-Kbps subchannels for Half Rate support (16 per two 64K timeslots) 1-16 Memotec Inc.