Solution Overview

IPTube G4 Abis
The Engage IPTube ABIS optimizes cellular backhaul using ABIS protocol for more efficient bandwidth use and lower capital expense per Base Station.

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 IPTube Abis

Abis Over IP Optimization

Mobile Backhaul Optimization Solution
The IPTube G4 Abis provides advanced optimization of 3GPP Abis traffic for efficient and cost effective GSM Cellular Base Station backhaul. Its Powerful and flexible Field Programmable Gate Array based Abis engine provides for the simultaneous full duplex optimization of 512 TRAU sub channels. The IPTube G4 Abis transports the optimized Basestation traffic over a WAN Circuit or as TDM over IP packets via wired or wireless Ethernet connections.

The major benefit of Abis optimization is significantly reducing backhaul bandwidth requirements by removing redundant traffic such as Silence Indicators, Idle Data and idle sub channels resulting in more capacity for service expansion or support for advanced subscriber applications.

The IPTube G4 Abis optimizer has two modes of operation: Fixed and Dynamic bandwidth. The Fixed bandwidth mode limits the amount of bandwidth to a specific number of 16 kilobit sub channels optimizing the Abis traffic into the available WAN T1/E1 timeslots or IP packet bandwidth. The Dynamic Abis optimization mode limits the aggregate IP packet bandwidth.

Optimized Abis Over Circuits
With configurable Abis optimization the number of T1/E1 circuits or timeslots required for backhaul is reduced by as much as 2:1 saving precious Opex, especially if the circuits are leased from another service provider. The additional capacity created can also be used to increase base station traffic load without additional T1/E1 Capex or Opex investment.

Abis Optimization 2 E1 to 1 E1
Optimized Abis Over Packets
Conversion of T1/E1 circuits to facilitate the use of IP/Ethernet connectivity eliminates or dramatically reduces Base Station to Base Station Controller backhaul Opex. Adding Fixed Abis optimization to this solution enables the use of bandwidth limited IP transport such as Satellite and xDSL for mobile backhaul. With Dynamic Abis optimization traffic loading of broadband networks is further minimized, reducing the cost of IP connectivity and freeing bandwidth for other applications.
E1 Abis over IP

GSM Abis Optimization
The interface between the BTS and BSC is a 3GPP reference interface called the Abis interface. The physical trunk connecting a BTS and BSC is typically a T1/E1 circuit, and carries 24 (T1) or 32 (E1) separate 64 kbps DS0 channels.

The IP•Tube G4 Abis has 1 to 4 Telecom interfaces that can be configured as full or fractional T1 or E1. The Abis traffic is optimized and encapsulated into Ethernet packets for transport over LANs, WANs, MANs, IP Satellite, xDSL, Cable and Wireless Ethernet. The Ethernet Switch provides transparent LAN bridging, user data bandwidth and access control through rate limiting and port-based VLAN filtering and tagging.

Engage’s Abis Optimization produces bandwidth efficiency increases of 33% to 50%, depending on the nature of the traffic on the Abis interface whenever a voice user is silent which is typically 40-60% of the time, which corresponds to a GSM voice call capacity gain of 50-100% per T1/E1.

Idle Channel Suppression
When a sub-rate DS0 is not assigned to a call, a repeating idle pattern is transmitted in accordance with 3GPP TS 08.54 v8.0.1. The Abis Optimization only transmits the idle state of the sub-rate DS0.

The voice and data bearer traffic is carried over the sub-rate DS0s in transcoder and rate adaptor (TRAU) frames in accordance with 3GPP TS 08.60 v8.2.1.
TRAU frames are generated when a sub-rate DS0 is assigned to a call. The transcoder and rate adaptation control function that specifies the TRAU frames provides several opportunities to optimize the Abis interface traffic types:

Idle Speech Frames/Idle Data Frames - Compression of repetitive data patterns as detailed in 3GPP TS (Technical Spec) 08.60 for Full and Enhanced Full Rate Traffic (sects 3.4 & 3.5.5).

Idle Data Pattern – Compression of Layer 1 Idle Pattern, as detailed in 3GPP TS 8.54 – Layer 1 Structure.
Silent Speech frames– Monitoring of Discontinuous Transmission (DTX) for Silence Descriptor (SID) indicator. Reference GSM 06.81

Signaling Optimization – Signaling is based on LAP-D and will be transported as HDLC-over-IP. Provides more robust transport and reduced bandwidth..

Other TRAU Frames (O&M, Data,etc.) transported in a transparent manner.

HDLC Idle Suppression
The DS0 channels that are used to carry control and signaling traffic utilize HDLC, a synchronous serial link protocol, with idle flags during the intervals between messages. Engage’s Abis Optimization technology eliminates these idle flags and only transports the HDLC framed messages.

Enable One to Four T1/E1 to IP interfaces supporting ABIS Base Station Controller to Base Station communication

The IP•Tube ABIS is designed to provide highly efficient bandwidth usage for cell backhaul from Base Station to Base Station Controller circuits. The majority of Cell site backhaul circuits in use today are TDM T1 or E1 circuits. Designed to carry 24 or 32 digital voice/data channels, converting these circuits to IP for broadband backhaul is a major task in the future installations of higher speed GSM cell services. The Engage IP Tube has been an important building block in the conversion of TDM to IP for cellular backhaul applications due to its reliability and economical installations.

ABIS is a 3GPP protocol for communication between the Base Station Controller (BSC) and the Mobile Base Station (BS). ABIS system interfaces include DSO bearer channels that can be used as sub-rate voice or data carriers. The interface includes in-band control signals that are carried as part of the channel traffic. Optimization of the ABIS interface is enabled by minimizing control traffic when it is repetitive and predictable. During silent intervals (no voice or data packets), the bearer channels send a repeated series of bits to the far end. The IP•Tube ABIS recognizes these idle patterns and reduces their transmission over the backhaul network. This intelligent channel control can provide up to 50% reduction in BSC to BS network traffic.

This available bandwidth means existing TDM circuits can carry more traffic, voice and data, with no additional Capital Expense (CAPEX). As areas are upgraded beyond 2G services, increased users can be supported by the backhaul network without adding additional TDM circuits. Additionally by using the IP•Tube ABIS, remote cellular Base Stations can now be economically connected using satellite circuits or other more expensive techniques for backhaul, enabling the extension of mobile services to areas previously restricted due to access considerations.
 IP Tube G4 Abis Standard Features

Assured Delivery Protocol
In order to assure high quality communications over links with intermittent or noisy performance, such as Wireless or Broadband over Power Line, the IP•Tube G4 Abis employs Engage’s robust Assured Delivery Protocol with the following benefits:

• Packet out of sequence detection and re-sequencing
• Duplicate skipping
• Lost packet retransmission with configured delay.

Dynamic Host Configuration Protocol - DHCP
The IPTube G4 Abis can be configured to obtain its Internet Protocol network parameters: IP Address, Subnet Mask, Default Gateway, DNS; from a local DHCP server.

Domain Name Addressing
IPTube G4 Abis can be configured to use a Domain Name for the remote IP•Tube in place of a fixed IP address. This supports multiple mobile service provider installations with ease.

Dynamic DNS
IPTube G4 Abis can be configured to register their IP address with Dynamic Domain Name Servers for discovery by the IPTube at the other end of the T1/E1 circuit. DDNS support combined with DHCP make installations Name-based which is very easy to setup and maintain when compared to Static IP addressing.

Secure Socket Shell - SSH
Engage’s Secure Socket Shell, which is based upon industry proven Open SSH and FIPS 140 approved Open SSL version 2.0, provides secure encrypted communications between SSH clients such as OpenSSH, SecureCRT, and PuTTY and the IPTube’s Command Line Interface.

IPTube G4 Abis can be fully managed with SNMP via standard and private MIBs. Large scale deployments of IPTubes with centralized management made SNMP support a priority. SNMP Traps for error events enable proactive service fault isolation.

Ethernet Switch
IP Tube ABIS is designed with a built-in four port 10/100 Ethernet QoS switch integrating a high-performance switching fabric with four priority queues. Advanced features include 802.1p/IPv4/IPv6 traffic classification, full IEEE 802.1Q VLAN, RMON, SNMP, Port Monitoring and Layer 2 firewall. QoS determined by destination MAC address, port ID, IEEE 802.1p and multimedia traffic tags, IPv4 Type of Service (TOS), and Differentiated Services (DiffServ).

Rate Limiter
The Ethernet switch Ingress and/or Egress Rate Limiter option enables the reservation of bandwidth for time-sensitive T1/E1 Over IP real time connections. Required for applications where LAN traffic can exceed the WAN bandwidth required by the T1/E1 over IP/Ethernet application. The data rate limit range is 128 kilobits to 64 Megabits in binary increments.

The Rate Limiter option limits WAN bandwidth utilized by the LAN1 to LAN2 bridge. Rate Limiting the traffic enables the reservation of the WAN bandwidth for times of high data usage versus periods of mainly voice traffic. Rate Governing is only applied in the direction to the WAN to minimize latency. .



 IP Tube G4 Abis Optional Features

Protector OPTION -PRO
The protector option utilizes the Ethernet Switch port ETH1 as a redundant path for the interconnection of the IP encapsulated T1/E1 data.

The PRO Option is configured to Always-On, or with Switch-Over criteria.

Alternator OPTION -ALT
The Alternator option alternatively sends the IP packetized T1/E1 frames on two Ethernet interfaces, balancing the load.

The Alternator option enables fractional and full T1/E1 circuits to be split over two IP WAN connections such as ADSL.

Pay-As-You-Grow Field Upgrades
The IPTUBE G4 ABIS is designed for Pay-As-You-Go growth from 1 thru 4 T1/E1s per unit. Customers can elect to economize initial network installations, by purchasing their IPTUBE G4 ABIS with a single active port. As the network grows enable additional Ports via a software-based license key. Additionally any port on the IPTUBE G4 ABIS cam be configured as T1 or E1, so a unit supports a mixed combination of ports. This permits even T1 standard sites to utilize the extra bandwidth of E1 circuits as interfaces when needed for additional back-haul throughput.
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