eclipse packet node in the mobile network etsi white paper

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September 23, 2010

ECLIPSE PACKET NODE IN THE MOBILE NETWORK ETSI

EXECUTIVE SUMMARY

Base stations that can connect devices at up to 50 Mbit/s or more will be operational within the next few years. For the backhaul network, the extra capacity needed and the mix of services to support legacy 2G and emerging 3G and 4G technologies will require changes in the technology used—IP/Ethernet will be the transport technology of choice.

This paper introduces the technologies for transitioning wireless backhaul networks to Ethernet, and the transport and management solutions provided by EclipseTM Packet Node from Aviat Networks.

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Eclipse Packet Node in the Mobile Network - ETSI

2 AVIAT NETWORKS September 23, 2010

TABLE OF CONTENTS

EXECUTIVE SUMMARY ........................................................................................................................... 1

SUMMARY ................................................................................................................................................. 3

INTRODUCTION ....................................................................................................................................... 3

ECLIPSE PACKET NODE ......................................................................................................................... 4 PLATFORM ................................................................................................................................................................. 5 PLATFORM INTEROPERATION ............................................................................................................................... 5 OPERATIONAL MODES ............................................................................................................................................ 6

TDM ONLY ......................................................................................................................................... 6

MIXED-MODE TDM+ETHERNET ..................................................................................................... 6

MLPPP................................................................................................................................................ 7

ALL-ETHERNET ................................................................................................................................ 7 NETWORK RESILIENCE ........................................................................................................................................... 7

PLATFORM PROTECTION ............................................................................................................... 7

LINK/PATH PROTECTION ................................................................................................................ 7

INTERFACE PROTECTION .............................................................................................................. 7

NETWORK PROTECTION ................................................................................................................ 7 ETHERNET FEATURES ............................................................................................................................................ 8

SWITCH CAPACITY .......................................................................................................................... 8

TRAFFIC SHAPING ........................................................................................................................... 8

THROUGHPUT OPTIMIZATION ....................................................................................................... 8

SYNCHRONIZATION ........................................................................................................................ 9

LINK AGGREGATION ..................................................................................................................... 10

ETHERNET INTERFACE PROTECTION ....................................................................................... 10

CARRIER GRADE OPERATION ..................................................................................................... 11

CARRIER GRADE OAM .................................................................................................................. 11

LINK CAPACITY AND SPECTRAL EFFICIENCY .................................................................................. 12 ADAPTIVE CODING AND MODULATION .............................................................................................................. 12 CO-CHANNEL DUAL POLARIZED LINKS (CCDP) ................................................................................................ 14

STRONG SECURITY .............................................................................................................................. 15 PAYLOAD ENCRYPTION ........................................................................................................................................ 15 SECURE MANAGEMENT ........................................................................................................................................ 16 RADIUS CLIENT ....................................................................................................................................................... 16

CONCLUSION ......................................................................................................................................... 16

GLOSSARY ............................................................................................................................................. 17

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SUMMARY Data services will grow to use more network capacity than voice. More network capacity translates to more backhaul capacity. Coupled with this is the recognition that IP/Ethernet is the transport media of choice for expanded backhaul services.

For many operators the introduction of Ethernet will be on the back of existing TDM network connections given their huge investment in its infrastructure. This will typically involve gradual migration using data overlay, with a decision at some future point to change to an all packet-based network. The transition phases may well include instances where there is a need to transport Ethernet alongside TDM, or Ethernet over TDM, and do so in a flexible, secure and cost efficient way.

Whatever the need, Eclipse Packet Node provides optimized solutions through its unique packet and circuit switched architecture for Ethernet and TDM.

Assisting the upgrade route are Packet Node solutions for better spectrum efficiency. Using high-order modulation, adaptive modulation and co-channel options, more traffic can be transported more efficiently on existing channel bandwidths.

Carrier grade Ethernet performance is provided on an intelligent Layer 2 switch to ensure Ethernet data transport is no less secure than for TDM. When coupled with advanced traffic prioritization, RSTP, link aggregation, network synchronization, bandwidth optimization and traffic aggregation, there is a Packet Node solution for all microwave network topologies.

Security is also a high profile issue. Although microwave radios have security-like features such as scrambling, narrow beamwidth, proprietary airframe coding and other factors, it is not hard to break given the expertise and intent. The Strong Security suite for Eclipse offers solutions for strict wireless network protection through Payload Encryption, Secure Management, and RADIUS Client.

The backbone for this capability is the Eclipse INU where software applications and plug-in cards upgrade existing Eclipse Node capabilities to Eclipse Packet Node. There is maximum retention of existing Eclipse hardware and software, which equates to maximum value-add and minimum disruption to existing services.

Finally, Eclipse comes with an assurance from Aviat Networks that value-adds will continue to become available to existing and new Eclipse customers to deliver more features and more performance. It is a promise of low-risk, low incremental cost, and a future-proof investment in Eclipse.

INTRODUCTION Typically, a small number of E1s has been sufficient to service 2G and 2.5G base stations, but with the data capacity needed for advanced 3G and 4G HSPA/LTE applications, new technologies and strategies are required.

This need for more capacity must be provided more intelligently, and more efficiently, especially so where the backhaul networks are, or will be required to support multiple services and customers—not just cellular mobile, and not just one operator. There is also a need to ensure service continuity for old and new technologies, given that operators will want to maximize investments in existing 2G/3G infrastructure.

Going forward, the most cost-effective backhaul technology to deliver more capacity, more intelligently, is Carrier Ethernet. It provides the scalability, flexibility and QoS features needed to provide a complete solution—from the core to base stations.

In networks where wireless provides the backhaul, these developments raise some issues. For example, how do you upgrade wireless connections for more capacity? Do you increase capacity of


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current TDM links? Do you overlay with Ethernet for extra capacity? Do you move to all-Ethernet?

Whichever way is forward, there is a cost efficient solution using Eclipse. Of special note is that one Eclipse Packet Node now supports up to six links and a programmable total nodal throughput of more than 2 Gbit/s Ethernet, and up to 100xE1 or 2xSTM1.

ECLIPSE PACKET NODE Eclipse Packet Node is the most flexible wireless platform for network migration. With a multi-link capability, advanced features for high capacity packet transport and intelligent IP networking, coupled with support for TDM, it delivers complete solutions for transitioning networks from TDM to IP.

At the heart of Eclipse Packet Node is a unique data packet plane (DPP) that operates independently of the circuit-switched backplane. The DPP routes Ethernet traffic directly between its GigE switch and packet radio modem(s) to deliver maximum payload efficiency with lowest latency. The backplane also connects radio modem(s) to support hybrid mixed-mode operation and to access wider aggregation and synchronization options. In combination, they optimize transport options for Ethernet and for Ethernet+TDM.

Plug-in-card and software options ensure there is always the right option available to meet current and projected needs. Cards are hot-swappable for easy reuse/relocation, as and when needed.

Packet Node features include:

• Advanced GigE switch with 1+1 redundancy options

• High-capacity links with QPSK to 256 QAM ACM and XPIC/CCDP options

• Advanced L1 and L2 link aggregation

• ML-PPP Ethernet over NxE1

• Synchronous Ethernet

• Easy upgrades with low incremental cost

• Maximized flexibility and scalability for Ethernet or Ethernet +TDM

• Comprehensive OAM capabilities in conjunction with its ProVision EMS.

Figure 1. Packet Node High-level Architecture


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The data packet plane (DPP) supports multiple GigE connections with link capacities to 366 Mbit/s and L1 throughputs to 455 Mbit/s.

The circuit plane (backplane) interoperates with the DPP to support native mixed mode Ethernet + TDM, with PDH capacities up to 100xE1. Mixed-mode operation accommodates a low-risk PDH now and Ethernet tomorrow transport philosophy.

• Packet Node backplane connections support Ethernet plus Super-PDH, with capacities up to 200 Mbit/s or 100xE1 in 2 Mbit/s / E1 steps.

• DPP connections support up to 2 Gbit/s aggregated.

• DPP and/or backplane traffic is connected to one or more radio modem cards, which in turn connect to an RF unit (ODU).

PLATFORM Packet Node is a split-mount platform, comprising the INU or INUe with one or more ODUs. The INU directly supports up to three links; the INUe up to six.

• Operation on licensed bands 5 to 38 GHz

• Each link can be configured for an air-capacity to 366 Mbit/s

• With data optimization techniques, each supports L1 throughputs to 455 Mbit/s

• An INU or INUe is simply populated with the mix of cards needed at any time to provide the required performance and operation

• Equipment, cabling and rack space is dramatically reduced

• Cards are hot-pluggable for easy upgrading and maintenance

Two ODU Options:

• ODU 300hp for frequency bands 6 to 38 GHz

• ODU 300ep for 5 GHz

PLATFORM INTEROPERATION Eclipse Packet Node supports over-air linking with the Aviat Networks IDU GE 20x or IDU ES for edge-of-network 1+0 connections. These IDUs are radio terminals, comprising an IDU and ODU; unlike Eclipse Packet Node they have no multi-link capability. They can be used as a single link, or networked where IDUs are back-to-back connected via their tributary ports at intermediate sites.

For IDU GE 20x a built-in Ethernet switch supports capabilities similar to those on Eclipse Packet Node. On the IDU ES the built-in switch function is more basic.

• Operation on licensed bands 6 to 38 GHz using ODU 300hp

• Configurable for air-capacities to 200 Mbit/s when air-interfaced to Eclipse Packet Node

• L1 throughputs to 250 Mbit/s

• Ethernet plus up to 20x E1 trib circuits for IDU GE 20x, or up to 8xE1 for IDU ES


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Both IDU GE 20x and IDU ES provide powerful, cost-efficient hybrid or all-Ethernet solutions where the multi-link capabilities of Eclipse Packet Node are not needed for last-mile connections.

OPERATIONAL MODES Eclipse Packet Node supports link configurations for TDM only, Mixed-mode Ethernet + TDM, MLPPP for Ethernet over NxE1, or all-Ethernet. Transitioning from one mode to another is a straight-forward process.

TDM ONLY Eclipse supports link capacities to 100xE1, or 2xSTM1.

MIXED-MODE TDM+ETHERNET Hybrid mixed-mode transports native Ethernet side-by-side with TDM. It enables Ethernet to be overlaid on a TDM network to meet the rapidly growing data demand. It means investments in existing TDM infrastructure can be maximized, and the risks associated with the introduction of Ethernet minimized. Network synchronization is maintained via the TDM connections, something not possible with Ethernet without resort to purpose-built sync solutions.

The ratio of link capacity assigned between Ethernet and TDM can be changed at any time.

Figure 2. Mixed Mode

Adding Ethernet to an NxE1 link simply requires installation of a GigE card, at which point an operator can locally or remotely configure the capacity split between PDH and Ethernet in E1 or 2 Mbit/s steps. It means Ethernet can be activated when and where needed in the network with minimal disruption. There is no loss of transport efficiency when a mixed-mode link is ultimately migrated to an all-Ethernet payload.

When more data capacity is needed, Eclipse options include adaptive modulation, or link aggregation with XPIC/CCDP to double or quadruple traffic bandwidth.

Figure 3 illustrates possible mixed-mode configurations. Capacities indicated are airlink capacities.

Figure 3. Mixed-mode Eclipse Packet Nodes


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MLPPP MLPPP (Multi-Link Point-to-Point Protocol) is based on PPP, a standards-based data-link-layer protocol. MLPPP bonds multiple PPP connections to support one connection with a capacity totalling the individual connections. With Eclipse, MLPPP is used to leverage existing capacity on legacy TDM links whereby multiple E1 circuits are bonded together to support one high-capacity connection for Ethernet. It enables retention of end or mid-point legacy NxE1 links (short or long term) within a network during migration to Ethernet.

Figure 4. MLPPP, Ethernet Over Multiple E1s

ALL-ETHERNET Transition to all-Ethernet operation can be engineered at any time. The transition can be directly from TDM, where TDM traffic is replaced by Ethernet, or from an intermediary mixed-mode solution, where the TDM traffic is phased out in favour of Ethernet.

• Changing to all-Ethernet operation on existing Eclipse TDM links is a simple upgrade; an Ethernet switch card is installed and the TDM interface card(s) removed.

• Changing from mixed-mode Ethernet+TDM to all-Ethernet only requires a configuration change. All link capacity is simply directed to Ethernet, and the TDM interface card(s) removed.

• However, transition to all-Ethernet will require a sync solution where the supported equipment requires a network-sourced clock reference. Eclipse supports various options. See SYNCHRONIZATION.

NETWORK RESILIENCE Eclipse Packet Node elements detect and recover from incidents without affecting priority users. Protection options support user interfaces, links, platform and network.

PLATFORM PROTECTION INU platform management and power supply functions are protected using an optional protection card.

LINK/PATH PROTECTION Protection options include hot-standby, space diversity, frequency diversity, or hybrid dual diversity.

INTERFACE PROTECTION Card redundancy is used to provide comprehensive protection of Ethernet and TDM interfaces. A second card of the same type is installed and configured so that traffic is transferred to the standby card on failure of the operational card.

NETWORK PROTECTION Network-based protection is provided for Ethernet and TDM.

Ethernet redundancy is supported on ring networks using RSTP, and on link-aggregated links.


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• RSTP is enabled on Eclipse RWPR™, which accelerates industry-standard RSTP (802.1D-2004) with a unique rapid failure detection (RFD) capability to provide reconvergence (service restoration) times as low as 50 ms on wireless links.

• Link aggregation - sometimes referred to as N+0 protection. If one link fails, its traffic is directed onto the remaining link(s), typically within 10 ms. If the remaining link(s) do not have the capacity needed to avoid a traffic bottleneck, QoS settings are used to ensure higher priority traffic continues to get through. Uniquely, Eclipse offers Layer 1 (L1) and Layer 2 (L2) link aggregation options.

For TDM ring networks Eclipse Super PDH protects ring capacities to 75xE1. Rings are implemented by east/west facing links to form a closed loop. Both North Gateway or Any-to-Any ring topologies are supported.

ETHERNET FEATURES An extensive range of switch-based options support the transport, aggregation and protection of Ethernet traffic, and the synchronization of devices supported from the network.

SWITCH CAPACITY The GigE switch has both electrical 10/100/1000Base-T and optical 1000Base-LX ports. Optical SFPs are available for 1300nm single or multimode, or 850nm multimode.

• One DAC GE3 in an Eclipse INUe supports an aggregate capacity to 2+ Gbit/s - one DAC GE3 directly supports up to six separate radio links.

• The switch has three RJ-45 and two optical SFP front panel ports, plus six backplane ports. The front panel ports are for user-connections and direct Data Packet Plane (DPP) connection to high capacity radio modem cards. The backplane ports also provide connection to radio modem cards.

• There is full bi-directional support for Jumbo frames to 10 Kbytes.

TRAFFIC SHAPING Traffic shaping and prioritization tools provide a means to efficiently manage traffic transiting Eclipse links. They particularly apply where available Ethernet bandwidth can be oversubscribed to ensure high priority traffic continues to get through – at the expense of lower priority traffic. Tools provided by Eclipse Packet Node include:

• Queuing with 136 Kbytes of memory on each ingress/egress port pairing to provide good balance between burst management and latency.

• Priority Mapping options on ports and on 802.1p and DiffServ tags to shape packet access to available bandwidth. Eight QoS queues per port maximize flexibility for transporting different traffic types with related priorities.

• Priority Scheduling with extended options for WRR, strict, and hybrid WRR + strict.

• Traffic Classification by VLAN Q and Q-in-Q tagging using the CoS/802.1p prioritization bits. Tagging can be retained into an external network for downstream traffic management.

• Flow Control option to throttle back data from sending devices and thereby reduce demands on restricted Ethernet bandwidth.

THROUGHPUT OPTIMIZATION Ethernet throughputs are maximized through use of IFG and Preamble suppression. This involves a reduction of the byte-count used to transport Ethernet data end-to-end over a link, thereby increasing data transport efficiency; more link capacity is made available for payload data.


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• The IFG and Preamble frame bytes carry no payload data - they can therefore be suppressed for transmission over a radio link and reinstated at the far end. The benefits are most apparent on small frame sizes where the IFG and Preamble bytes are a higher percentage of the frame total.

• The reduction in frame space improves throughput 23 percent on 64-byte frames, 6 percent on average-size 260-byte frames, reducing to 1% on 1518 byte frames.

SYNCHRONIZATION Mobile base stations must be synchronized to support hand-off between cells, and to ensure frequencies on the air-interfaces have the accuracy and stability needed to minimize channel interference.

• For GSM / UMTS nodes on a wireless backhaul network, required frequency synchronization has traditionally been met by using the clocking from a TDM (E1) connection.

• For CDMA nodes requiring a time-referenced phase sync source, clocking has typically been provided by a GPS receiver installed at the site.

• For next generation 4G/LTE base stations, phase synchronization is an expected requirement.

On networks where synchronization is provided via TDM network clocking, the quality of this clocking must be maintained during migration to IP/Ethernet. At issue is the nature of standard 802.3 Ethernet; it is asynchronous - it contains no provision for transferring a clock reference.

But there are solutions through Synchronous Ethernet, or IEEE 1588v2 packet-based timing. Eclipse Packet Node supports both, plus options for clock maintenance through mixed mode, or Eclipse Distributed Sync.

Currently only IEEE 1588v2 has an ability to support phase synchronization over an Ethernet connection.

Synchronous Ethernet

Synchronous Ethernet transports timing information using a clock signal injected into the bit stream, much like TDM. Each device in the network recovers, cleans, and then distributes the clock to its downstream neighbor. It means every intervening node (switch/router) within the network must support Synchronous Ethernet.

• SyncE can only distribute frequency; it cannot distribute phase alignment or time of day (ToD).

• SyncE clocking is unaffected by data delivery impairments in the higher packet-plane layers, such as the delays caused by queuing and re-routing on heavily loaded networks.

• Clock quality requirements (jitter and wander) are equivalent to that specified for TDM networks within G.823 / G.824. Clock transfer is supported between TDM and SyncE sections of the same network.

• On Eclipse radio links the clocking to support SyncE operation uses Eclipse Distributed Sync.

• Upgrading to Synchronous Ethernet simply requires installation of a DAC GE3 switch card, and a SyncE feature license.

IEEE 1588v2

1588v2 is a Precision Timing Protocol (PTP) for phase and frequency synchronization. Dedicated timing packets are transmited within the data packet stream to maintain a Master-Slave synchronization relationship.

• Time-stamped PTP packets are sent from the master clock to the slave clocks, and from the slave clocks back to the master. A timing recovery algorithm uses these packets to calculate and offset the delays and differences in delay (packet delay variation or PDV) across a network.


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• PDV represents the most significant impairment factor – synchronization accuracy can be affected on heavily loaded networks.

• Because it works in the IP data path it does add a small amount of additional traffic to the network.

1588v2 frames are transported transparently by Eclipse Packet Node.

Mixed Mode

Eclipse uses the TDM links within mixed mode Ethernet+TDM links to retain support for traditional TDM clocking. It particularly applies to networks where Ethernet is introduced on the back of existing TDM network connections.

Eclipse Distributed Sync (EDS)

Eclipse Distributed Sync multicasts an E1 circuit throughout the network to maintain existing TDM clock accuracy and stability. It supports flexible migration without compromising existing TDM synchronization. EDS also provides a totally reliable and risk-free timing solution for Eclipse SyncE connections.

• Instead of a dedicated E1 circuit per destination, one E1 is used throughout the network for all destinations. It is for sync purposes only. At network nodes the E1 is captured from the incoming link, and included as required on outgoing links.

• While an E1 is included alongside the Ethernet data on each link, the effective cost of this usage is small compared to the time, risk and cost of implementing generic IEEE 1588v2 or Synchronous Ethernet solutions.

EDS provides a seamless frequency synchronization solution when migrating from TDM to an all-Ethernet backhaul. It is fully scalable from small to large networks, and its multicast nature means it is available at all points within an Eclipse network.

LINK AGGREGATION Link aggregation combines two or more links into a single logical link to provide a traffic capacity that is the sum of the individual links. It is especially relevant to wireless links that require traffic capacities higher than the maximum possible on one radio channel link - two links are operated in the same RF channel using CCDP, then link aggregated to provide one logical link of twice the capacity.

Link aggregation also provides redundancy. If one link fails, its traffic is redirected onto the remaining link(s). Effectively this is N+0 protection - all links in the aggregation group carry traffic, and provide protection for each other. If the remaining link(s) do not have the capacity needed to avoid a traffic bottleneck, QoS settings ensure all higher priority traffic continues to get through.

Eclipse Packet Node has L1 and L2 link aggregation options:

• L1 aggregation acts on the byte data stream. Unlike L2 link aggregation, it provides optimum payload sharing regardless of individual connection throughput demands - ideal for router-router connections.

• L2 link aggregation (802.3ad) uses source and/or destination MAC address data in the Ethernet frame MAC/LLC header.

ETHERNET INTERFACE PROTECTION Two configurations are available to support protection of the GigE switch cards, one based on the BFD protocol (Bidirectional Forwarding Detection), the other on Y-cables.

BFD is designed for fast path failure detection on Ethernet and other media. Separate connections are established from paired GigE cards based on VLANs and the BFD protocol. If BFD detects a failure of the primary VLAN or physical interface, all traffic is automatically allocated to the secondary VLAN to provide true 1+1 protection on Eclipse and the connected equipment.


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Y-cable protection is used where the connected equipment does not support BFD. A single connection is established to the connected equipment from paired GigE cards. Full 1+1 protection is provided on Eclipse, but not on the connected equipment.

CARRIER GRADE OPERATION Carrier Ethernet is defined by the MEF (Metro Ethernet Forum) as a ubiquitous, standardized, carrier-class service. Various attributes distinguish it from familiar LAN based Ethernet.

Essentially is about network transport infrastructure and service delivery. The underlying principle is that the attributes of Carrier Ethernet are met in the Access, Metro and Core networks to deliver a seamless, performance and cost optimized solution between all users.

For an Ethernet device to be considered carrier grade, it must meet relevant MEF requirements. Those for standardized services, reliability, scalability, QoS and service management are specified within MEF 9 and MEF 14.

• MEF 9 specifies the UNI (Universal Network Interface)

• MEF 14 specifies the QoS (Quality of Service) parameters.

Eclipse Packet Node is certified compliant with these standards to provide an assurance that it will interoperate with other certified carrier Ethernet devices, now and into the future.

Aviat Networks is also a founding member of the MEF Mobile Backhaul Group, whose aim is to promote and define the use of Carrier Ethernet services for mobile/cellular networks.

CARRIER GRADE OAM The ProVision EMS for Eclipse supports relevant requirements within ITU Y-1731 for the service layer and within IEEE 802.3ah for the link layer. Every Eclipse device in a network is visible to network operators together with the tools needed to determine device and network status and performance, and to effect changes when needed. Features include:

• Fully integrated management of the radio and its Ethernet traffic. For example, where Ethernet performance is being affected by radio performance, the problem is easily diagnosed using common user-friendly interfaces.

• Ethernet diagnostics with RMON performance data, Ethernet history, and Ethernet data-dashboards for throughput, errors and discards.

• End-to-end network mapping, circuit provisioning and performance monitoring at service (VLAN) and link levels.

• Strong security is supported via SNMPv3 and a RADIUS Server option.

• A Multi-Technology Operations System Interface (MTOSI : TMF 854) supports ProVision interfacing with MTOSI-standardized management systems.

• Error events with probable cause and remedial advice.

• Site energy and security management with system status, fault management, fuel usage reporting and energy control history.


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Figure 5. Example ProVision EMS screens for Network Health and Bandwidth Utilization

LINK CAPACITY AND SPECTRAL EFFICIENCY Superior capacity and spectrum efficiency gains are a feature of Packet Node through adaptive coding and modulation (ACM), and co-channel dual polarized (CCDP) link operation.

ADAPTIVE CODING AND MODULATION Instead of using a fixed modulation rate to provide a guaranteed capacity and service availability under all path conditions, the modulation rate, and hence capacity, is increased when path conditions permit to provide a higher capacity. Typically, this higher capacity will be available for more than 99.5 percent of the time.

• Adaptive modulation is the dynamic adjustment of modulation rate to ensure maximum data bandwidth is provided most of the time, with a guaranteed bandwidth provided all the time.

• A link may be designed to have as much as 30 dB of fade margin to support 99.999% availability. However, this is only needed to protect the link against worst-case fades that may occur just a few minutes in a year. For the rest of the year, the margin is not used.

• By using less robust but more efficient modulation schemes, the available fade margin is transformed into delivering more data throughput - adaptive modulation dynamically changes the modulation so that the highest modulation and hence highest availability of capacity is provided at any given time.

• When used in conjunction with QoS traffic shaping and prioritization, it can be configured to ensure all high priority traffic continues to get through when path conditions deteriorate; only low priority “best effort” data is discarded.

Figure 6 illustrates Packet Node modulation/capacity steps and typical percent availability over time for QPSK to 256 QAM ACM. QPSK, as the most robust modulation, is used to support the critical traffic. Less critical traffic is assigned to the higher modulations. Most importantly, the highest modulation is typically available for more than 99.5 percent of the time and supports four times the capacity of QPSK.


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Figure 6. Adaptive Modulation at Work

Packet Node adaptive modulation is an end-to-end solution for Ethernet only, or a combination of Ethernet and TDM.

It uses one of four automatically and dynamically switched modulations - QPSK, 16 QAM, 64 QAM or 256 QAM. Uniquely, each modulation has two coding options, one for maximum throughput, one for maximum system gain, to provide a total of eight modulation states, any four of which can be selected for ACM.

• Maximum throughput delivers maximum data throughput - at the expense of some system gain. Maximum gain delivers best system gain - at the expense of some throughput.

• When all four modulations are selected (QPSK to 256 QAM) , each can be set for maximum throughput or maximum gain.

• With three modulations selected, such as 16 QAM, 64 QAM and 256 QAM, one rate (any) can be set for maximum gain and additionally for maximum throughput, to provide four step AM operation. Or just three (any) of the four possible steps can be selected.

• With just two modulations selected, such as 64 QAM with 256 QAM, or 16QAM with 256 QAM, each can be set for maximum gain and additionally for maximum throughput, to provide four step AM operation. Or just two, or three out of the four possible steps can be selected.

• For a given RF channel bandwidth, ACM provides a nominal two-fold improvement in data throughput for a change from QPSK to 16 QAM, a three-fold improvement to 64 QAM and a four-fold improvement to 256 QAM.

• Modulation switching is hitless. During a change to a lower modulation, remaining higher priority traffic is not affected. Similarly, existing traffic is unaffected during a change to a higher modulation. Traffic shaping is used to ensure best traffic efficiency (payload mapping) on each modulation.

• Ethernet connections enjoy real synergy through the QoS awareness on the GigE card and the service provisioning provided by any MPLS or PBB-TE network overlay. All high priority traffic, such as voice and video, continues to get through when path conditions are poor.


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• Any E1 connections are dropped in user-specified order when link capacity is reduced , and restored when capacity is increased.

Figure 7 shows the air-link capacities for each modulation, by channel bandwidth.

Figure 7. Eclipse Packet Node Adaptive Modulation Steps

CO-CHANNEL DUAL POLARIZED LINKS (CCDP) In situations where increasing the channel bandwidth and/or increasing the modulation rate cannot provide the capacity needed, CCDP provides an answer. It enables two links to operate on the same channel to double the wireless capacity.

• Under CCDP, two parallel communication links are operated on the same RF channel: one using the vertical polarization, the other the horizontal. Cross Polarized Interference Cancellation (XPIC) is used to ensure any interference between the channels is effectively eliminated.

• The capacity on each link can be used for IP, or IP+TDM.

• If both links are configured for IP traffic, the two traffic streams can be link-aggregated (L1 or L2) to a single customer user interface.

• CCDP Links can be 1+1 or ring protected.

• Where even higher capacity links are needed, three or four links can be installed. For example, two CCDP link pairs (four links in total) support 4x the capacity of a single link, using two RF channels.

Figure 8 illustrates a CCDP mixed-mode link on a 56 MHz channel with 256 QAM maximum throughput modulation. The combined link capacity of 732 Mbit/s is used for Ethernet + 16xE1. With IFG and Preamble suppression, the 700 Mbit/s available for Ethernet supports L1 throughputs to 870 Mbit/s.


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Figure 8. 732 Mbit/s Link Aggregated Mixed-Mode Link

Figure 9 illustrates a CCDP RSTP node with east-west links on 56 MHz channels with 256 QAM, Maximum Throughput modulation. With IFG and Preamble suppression, the links support Ethernet throughputs to 910 Mbit/s.

Figure 9. 732 Mbit/s Link Aggregated RSTP CCDP Ring Node

STRONG SECURITY Institutional and individual users assume their networked data and voice communications are held secure end-to-end. But given the reality that migration towards IP does provide increased opportunity for data and call interception, security on backhaul networks must be reviewed.

As well as security for the payload there is also the issue of securing the physical network to prevent equipment being compromised or taken over by unauthorized parties. At the other end of the scale, there is potential for unintentional miss-configuration by low-level but unauthorized users.

What’s needed is a high level of security for both payload and management traffic. Traditionally, microwave networks have not included such purpose-built capabilities.

Uniquely, Eclipse provides strong solutions. With Payload Encryption, Secure Management, and RADIUS Client, Eclipse Strong Security ensures there is no potential for non-secure access to the radio payload or to the management interfaces.

PAYLOAD ENCRYPTION Payload Encryption secures wireless data and in-band and out-of-band management traffic. Operation is FIPS-197 compliant and features an AES-CCM cipher suite with AES counter mode data encryption and CBC-MAC data integrity validation.The integrity of each data frame sent over the link is checked to ensure that received data has been sent by the intended transmitter, and if it detects that received data has been modified (man-in-the-middle attack), then received data is replaced with AIS.


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SECURE MANAGEMENT Secure Management offers secure management access to Eclipse Packet Node radios over unsecured networks. It protects the radio from accidental or intentional miss-configuration and provides centralized access control based on sophisticated permission attributes. An event logger records all management activity for proper accountability and optimum troubleshooting support.

Security is provided through use of encrypted communication protocols, a requirement for complex passwords, and protection against mechanized attacks. Communication encryption is based on a FIPS140-2. SNMPv3 is used to secure the management communication connections.

RADIUS CLIENT An integrated RADIUS capability enables authentication, authorization and accounting of user accounts from a remote RADIUS Server for central management of Eclipse user accounts.

The RADIUS remote server provides centralized management and authentication of user names, passwords, and access permissions, and ensures that all users have consistent access privileges throughout the network, using a common set of user credentials. When a user attempts to login to a RADIUS Client (Eclipse radio), the radio sends the authentication request to the RADIUS server. Communication between the RADIUS client and the RADIUS server is authenticated and encrypted, and the RADIUS server accounting database maintains a log of all requests, access times and durations.

CONCLUSION Eclipse Packet Node is optimized for transforming networks to all-IP. You can single-step from TDM to all-IP or go step-by-step starting with an overlay of Ethernet on existing TDM links and adjusting the overlay to ultimately reach an all-IP goal. At each step, there is a low-cost card or software based solution to support required network infrastructure for more capacity, better spectral and data efficiency, wider redundancy options, tighter QoS, sync options, legacy traffic support, and strong security.

This incremental approach has much to recommend it. Change can be made without the risk, downtime and expense often associated with a complete platform change-out. No other node offers the flexibility, scalability, low-cost migration, reliability and ultimate sophistication and capacity grunt for new generation wireless backhaul.


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GLOSSARY ACM Adaptive coding and modulation. AES Advanced encryption standard. An encryption standard adopted by the U.S.

government. It comprises three block ciphers, AES-128, AES-192 and AES-256. AIS Alarm indication signal. CCM Combined cipher machine. CBC Cipher block chaining. CCDP Co-channel dual polarized. EMS Element management system. FIPS Federal information processing standards. HSPA High speed packet access. LTE Long term evolution. Evolving standard for 4G mobile networks. MAC Media access control. MEF Metro Ethernet Forum. PDH Plesiosynchronous digital hierarchy. Asynchronous multiplexing scheme in which

multiple digital synchronous circuits run at slightly different clock rates. QAM Quadrature amplitude modulation. QoS Quality of service. QPSK Quadrature phase shift key. RADIUS Remote authentication dial In user service. RSTP Rapid spanning tree protocol. RWPR Resilient Wireless Packet Ring. SDH Synchronous digital hierarchy. Transmission rates range from 51.84 Mbit/s (STM0/OC1)

and 155.52 Mbit/s (STM1/OC3) through to 10-plus Gbit/s. SFP Small-form-factor pluggable. SLA Service level agreement. SNMP Simple network management protocol. TDM Time division multiplexing. Multiple low-speed signals are multiplexed to/from a high-

speed channel, with each signal assigned a fixed time slot in a fixed rotation. VLAN Virtual LAN. IEEE 802.1Q tagging mechanism. XPIC Cross-polarized interference cancellation. Some Eclipse Packet Node features may be subject to availability. Contact your Aviat Networks representative for details.



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