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8/2/2019 4G Compact Base Stations WP-Interphase

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COMPACT BASE STATIONS:

TAKING LTE WHERE YOU NEED IT

Scalability, low power use, and compact packaging increaseflexibility in base station deployments and coverage, enabling

innovative high-bandwidth network topologies


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White Paper Compact base stations: Taking LTE where you need it

Page 2 2010 Interphase

Contents

Executive Summary ....................................................................................................................................... 3

More data traffic, smaller base stations ....................................................................................................... 4

Data traffic growth creates the need for a new network topology .............................................................. 4

Getting off the groundthe compact base station ....................................................................................... 7

Offering more than high-density coverage ................................................................................................... 8

The value proposition of compact base stations ........................................................................................ 10

Interphases application-ready 4G module for compact eNodeB base stations ........................................ 11

Conclusion ................................................................................................................................................... 12


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Executive Summary

Fourth generation (4G) technologies like Long Term

Evolution (LTE) will usher in a new way to meet the

exploding demand for wireless data applications. Not

only does LTE provide higher data rates, it enables

mobile service providers to adopt a new network

topology that gives them the flexibility to meet

subscriber demand where it is high and to pack more

traffic into their spectrum bands.

Compact base stations are the nimble new entrants

that bring scalability and cost savings to the 4Gnetwork topology. They are designed to deliver:

High capacity, through deployment of smaller

base stations with a smaller coverage area.

Base stations that are closer to subscribers, and

small enough to be installed on a variety of

assetse.g., lampposts, outdoor building walls,

or indoor locations.

Low cost-per-bit, driving lower CAPEX and OPEX

for a lower total cost of ownership (TCO).

The emergence of compact base stations has been

driven by system-on-a-chip (SoC) technology that

makes it possible to combine the functionality of

layers 1 to 3 on a single chipset with multiple cores

digital signal processing (DSP), reduced instruction

set computing (RISC), applicationspecific integrated

circuit (ASIC)plus hardware accelerators. Compact

base stations with a single multicore SoC chipset can

support up to three sectors.

Interphases flexible LTE compact base station module is a highly integrated, application-ready solution

that leverages SoC technology to combine a small footprint and low power consumption with advanced

performance. The module is fully compliant with LTE standards and includes the control processor,

baseband, storage, and switch, along with APIs, drivers, and stacks. Support for multiple standards-

based form factors and customized designs allow vendors to develop broad product lines and

application-specific solutions while minimizing development costs and time. The tightly integrated

hardware and software architectures allow for efficient scalability, achieved with the combination of

baseband cards to increase capacity.

Why compact base stations?

Baseband, power amplifier, and

radio equipment in a single

ruggedized enclosure.

Small footprint, light form factor

(10 kg for a three-sector base

station; 500 g for an eNodeB

module).Low installation and equipment

cost.

No need for ground equipment or

active cooling.

Low power consumption (26 W to

36 W).

Flexible choice of installation sites.

Multiple base station form factors

and configurations, from multi-

sector macrocells, to microcells,

picocells, and femtocells.Same performance as traditional

ground-based or distributed base

stations.

Highly scalable through system-on-

a-chip technology, and single card

additions in the field.


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More data traffic, smaller base stations

Fourth generation (4G) technologies like Long Term Evolution (LTE) offer more than higher data rates

and capacity; they address rapidly evolving market conditions that require a new approach to network

planning and deployment.

New, flexible small-cell architectures, including microcells, picocells, and femtocells, are set to become

prominent elements in the new network topologies. Increasingly, these devices will be seamlessly added

to networks to increase spectrum efficiency and capacity density, and to keep costs under control.

As mobile service providers are pressed to increase capacity under tight time and budget constraints,

they can no longer afford to rely exclusively on traditional, expensive, and bulky ground-based macrocell

base station equipment to expand their networks. Now they can start out with compact, small-cell

equipment that is easier and cheaper to deploy, and incrementally build out the network as traffic

increases and a higher density of base stations is needed. Compact base stations combine the

performance of ground-based base stations with a smaller footprint and a lower price tag. They allow

carriers to increase the capacity in the network in direct response to subscriber and revenue growth onan as-needed basis.

Data traffic growth creates the need for a new network topology

Subscribers are adopting wireless broadband data services at an unprecedented rate, causing mobile

traffic to grow exponentially. This growth limits the number of users and their individual traffic loads

that a carrier can serve with its existing spectrum allocation. New technologies like LTE are designed to

provide additional capacity and higher data rates to relieve network congestion, but a new approach to

network deployment and expansion is required to address the demand for high-bandwidth applications

in a limited-spectrum environment:

Higher density. A higher density of base stations placed in closer proximity increases the overall

network capacity while utilizing the same amount of spectrum in a more efficient manner. More

base stations in a smaller radius allow more traffic to be transported within the same geographic

area.

Base stations closer to subscribers. In an environment with a high cell density, it is preferable to

place base stations as close as possible to the subscribers to avoid self-interference and to improve

indoor coverage.

Lower per-bit cost. Average revenues per user (ARPUs) are not expected to grow in line with the

increase in traffic generated by subscribers, so service providers need to lower the per-bit cost of

transmissionfor both CAPEX and OPEX itemsto continue to operate a sustainable business.

Traditional ground-based macrocell base station equipment was designed to provide maximum power

and coverage, and to minimize the number of base stations installed (Table 1, Figure 1). All the

hardware, with the exception of the antennas, is placed in an air-conditioned enclosure at the bottom of

the cell tower. This well-established macrocell equipment design is expensive in terms of equipment,

installation and operation costs, and has demanding ground space requirements, but it will undoubtedly

retain a crucial role in cellular networks for the foreseeable future. The traditional macrocell will remain

cost effective for providing wide-area coverage in environments where traffic levels are manageable.


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However, this deployment model will struggle to remain viable where a dense concentration of users

demand high bandwidth wireless access.

Distributed base stations leave the baseband and power amplifier within the ground enclosure, but

move the radio frequency (RF) equipment to the cell tower to be close to the antenna(Table 1, Figure

1). This approach reduces the power dissipation due to the use of coaxial cables in traditional, ground-

based base stations, increasing the energy efficiency and providing some limited reduction in the size

and weight of the equipment on the ground. While providing a reduction in cost and size, distributed

base stations still rely on ground equipment, which limits the flexibility of deployment and incurs the

cost of installing and operating the ground-based equipment.

Table 1. Comparison across base station architectures

Architecture Ground-Based Distributed Compact

Design

DescriptionTraditional base

station, installed in a

shelter on the ground

Baseband and power

amplifier (PA)

equipment in a shelteron the ground.

Radio equipment on

the mast, near the

antenna

Baseband, PA, and RF are in a single

enclosure which can be inside the antenna

enclosure (zero footprint), have a smallstand-alone enclosure, or be added as a

blade in a multifunctional system. No ground

equipment.

PerformanceSame throughput, latency, and coverage area,

assuming they use the same spectrum and transmission power

Form factor Macrocell, microcell, picocell Macrocell, microcell, picocell, femtocell

SectorsMacrocell: 1 to 8, typically 3

Microcell, picocell: typically 1 to 31 to 3 sectors

Equipment

BasebandGround enclosure

Ground enclosurePassively cooled unitPA

RF Passively-cooled unit

AntennaUsually in cell tower or on rooftop, not

integratedCan be integrated with base station unit

Connection to

backhaulCoaxial cable Fiber CAT-5 or fiber

Cooling Temperature-controlled ground shelter None needed

Other metrics

Power

consumption*100 W 2636 W**

Weight

15% to 25% of ground-based base station

weight**

Cost

Comparable to

ground-based base

stations

25% of ground-based base station**

* Base station, excluding cooling system and radio components

** Total depends on specific form factor and number of sectors


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Figure 1. Ground-based, distributed, and compact base stations

Both ground-based and distributed macrocell base stations are poorly suited for dense, high-capacity 4G

network topologies where high power and wide range are unnecessaryand often not desired, as they

may cause self-interferenceand where building new cell towers is difficult due to space and permitting

restrictions.

In dense deployments, microcell and picocell base stations will become more widely used in the 4G

network topology, complementing or replacing macrocells in at least two situations. One is downtown

environments where tall buildings make it difficult to establish good indoor and outdoor coverage. The

new small-cell topology enables service providers to create a dense network of cells installed close to

the subscriber and to increase capacity density. Another is providing fill-in coverage for macrocell areas

that have zones with limited or no cellular coverage, often in rural areas or environments with complex

RF propagation. Compact base stations enable mobile service providers to extend coverage to these

areas in a cost-effective way.

Microcell and picocell base stations that use a ground-based or distributed architecture have beenavailable for a long time. Even though they have a smaller footprint than ground-based macrocells, they

still require ground equipment and, as a result, are expensive to install and operate, use high levels of

power, and have demanding site requirements. As a result, micro and pico base stations still account for

a small percentage of installed base stations.

To enable high-capacity and dense deployments, service providers need access to equipment that is

small, can be installed on non-telecom assets, and is cost effective to purchase, install, and operate.


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Compact base stations have been specifically designed to address this challenge and give service

providers the tools to evolve to more flexible network topologies as they move to 4G.

Getting off the groundthe compact base station

In a clear departure from the traditional base station architecture, compact base stations eliminate the

need for ground equipment (Table 1, Figure 1). They strive to maximize traffic capacity and reduce the

costs of building and operating a network by being small and flexible, thus reducing both CAPEX and

OPEX. The compact architecture can be used for macrocells, microcells, picocells, and femtocells, but all

compact base stations share some key features:

Compact, lightweight form factor. Base stations can be installed on virtually any vertical surface or

pole. They can be installed on cell towers as well, but it is not required.

No ground equipment. If solar power and wireless backhaul are used, there is no need to have any

connection from the base station to the ground. Otherwise, only an Ethernet connection (typically

using CAT-5 or fiber) to the ground is needed to provide backhaul connectivity and power overEthernet [PoE].

System on a Chip (SoC) chipset. A single multicore chipset can support multiple sectors, and it is

fully compliant with the air interface standards.

Same performance as traditional equipment. Data rates for compact base stations are comparable

to those for ground-based or distributed base stations with similar configurations (e.g., spectrum

band or channel size).

Single ruggedized enclosure for baseband, PA, and RF. In some configurations, antennas may also

be integrated within the same enclosure; this is called a zero-footprint configuration.

Low power consumption.

Passive cooling.

Compact base stations include baseband, control, PA, and RF in a single low-power, passively cooled

package. They enable antenna placement in convenient, existing locations, whether mounted on an

existing cell tower, a lamppost, a building, or even a mobile vehicle. These small, powerful base stations

can be made in a variety of form factors: a zero footprint, a small stand-alone enclosure, or even a blade

where it makes sense to include the small cell application within existing server equipment for a

multifunctional system.

Zero-footprint base stations, the ultimate in compact size, reduce the base station to a module that is

mounted inside the antenna enclosure, similar to a femtocell but with the performance of a picocell or

microcell. Depending on expected user density, these extremely cost-effective base stations can support

from one to three sectors.

Stand-alone compact base stations can come in a variety of enclosures to suit the application, including

a ruggedized casing suitable for pole or building mounting, a ruggedized chassis for vehicle mounting,

and a standards-based, small-footprint chassis such as MicroTCA. These compact base stations can be

configured to handle picocell, microcell, or macrocell applications in this single enclosure, supporting

one to three sectors. They can even be configured to be a self-contained evolved packet core (EPC), as

well as a base station.


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The small form factor and low power consumption that sets compact base stations apart from

traditional equipment is enabled by the latest highly integrated system-on-a-chip (SoC) technology. SoC

multicore chipsets combine physical (PHY) layer (layer 1), media access control (MAC) sublayer in the

data link layer (layer 2), and, optionally, network layer (layer 3) functionality to support the

computationally intensive processing of 4G wireless interfaces. A compact base station SoC chipset has

multiple coresdigital signal processing (DSP), reduced instruction set computing (RISC) and

applicationspecific integrated circuit (ASIC) coresand hardware accelerators. A single SoC chipset can

support up to three sectors with 2x2 multiple input multiple output (MIMO) technology. Furthermore,

the tight integration of PHY, MAC, and layer 3 functionality within the same chipset minimizes the end-

to-end latency, which is crucial to real-time applications such as voice, video, or gaming. The RF can be

part of the base station or in a separate housing.

Since compact base stations are typically placed close to the antennas or inside the antenna enclosure,

this arrangement limits the power loss due to the coaxial cable used to connect the ground equipment

to the antennas, and substantially reduces the power requirement of the entire base station.

A three-sector compact base station, including the antenna, can weigh as little as 10 kg. Interphases

eNodeB module itself can be less than 0.5 kg. Because they do not require a shelter on the ground oractive cooling, compact base stations can be installed in virtually any locationfrom cell towers to

lampposts and vertical walls, and from rural assets to corporate campuses and indoor locations. The

only requirements to operate them are power and backhaul. However, energy consumption is

sufficiently low (26 W to 36 W for the processor core in a zero-footprint configuration) to allow solar

panels to power the base station or to use PoE. Furthermore, wireless backhaul can be used to further

reduce the size of the equipment and allow more flexibility in the positioning of the base station. As a

result, compact base stations present strong advantages for remote locations where power and wireline

connectivity are not available.

Crucially, however, compact base stations do not compromise on performance. Assuming the same

spectrum bandwidth and the same transmission power, performance of a compact base station iscomparable to that of ground-based or distributed base stations.

Offering more than high-density coverage

Compact base stations have been primarily developed to meet the demands of 4G high-capacity, high-

density networks, but their flexible form factor, low power consumption, and affordability make them

an ideal technological solution, also, for outdoor locations with multisector macrocell and microcells

(often used in rural deployments) and for indoor coverage with single-sector picocell and femtocells

(Figure 2).

Compact base stations are also well placed to support vertical applications in marketssuch as safety,

transportation, corporate, asset-tracking, and utilitieswhere equipment flexibility and affordability are

key requirements (Table 2). Because the eNodeB module used in all these configurations can be the

same, service providers can easily integrate and manage different form factors within their core

network.


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Table 2. Where can compact base stations be deployed?

Location Advantages

High-capacity dense urban

coverage

In areas with a high data traffic concentration, micro and pico compact base

stations may complement or even replace macrocells. A dense network of cells

installed close to the subscriber improves coverage in downtown environments

where tall buildings make it difficult to establish good indoor and outdoor

coverage with macrocells.

Fill-in underlay networks

In areas where macrocells provide sufficient capacity, there are often zones with

limited or no cellular coverage. In these areas, compact base stations can be

installed at the locations where coverage is insufficient. Because of their low

deployment and operating cost, compact base stations are typically a more cost-

effective solution than additional macrocells.

Indoor coverage

The majority of data trafficfor some service providers up to 80%is generated

at indoor locations, where weak coverage forces the adoption of modulation

schemes that use a proportionally greater use of network resources than for

outdoor traffic. Traffic at indoor locations can be off-loaded from the macro

network to compact base stations, thus freeing macro resources for the more

efficient transport of traffic from users located outdoors.

Rural coverage

Subscriber demand is typically very sparse in rural areas, and for this reason it is

difficult for a wireless service provider to build a solid business case for rural

deployments. With compact base stations, the financial proposition becomes

more attractive, as service providers can deploy low cost equipment on the

assets available to them in their coverage area.

Remote locations

Compact base stations powered by solar panels and connected to the backbone

through a wireless backhaul connection can cost effectively serve areas without

power and wireline connectivity.

Enterprise and public safetyapplications

Enterprises and public safety entities can benefit from compact base stations to

cover a well-defined, contained area, with good coverage and high capacity

density. They can create hot zones quickly and cost effectively to support

operational and safety applications. The scalability of SoC solutions for compact

base stations encourages vendors to develop additional products that use

spectrum bands that are license exempt, or reserved for specific applications or

users (e.g., bands reserved for safety applications or military use).

Vertical applications

Compact base stations are well suited for vertical applications such as asset

management, mobile workforce connectivity, remote monitoring and control,

metering, and other machine-to-machine (M2M) applications. For instance, in a

public rail transport environment, a compact base stations small footprint

facilitates trackside deployments along on the right-of-way, where space and

power availability are especially tight.

Compact base stations can also provide cost-effective coverage for locations with

specific requirements, such as cruise ships, hospitals, prisons, mining sites, orwarehouses.

Ad hoc mobile networks

For public safety, municipalities, and utilities, compact base stations can be used

to create temporary networks that can be quickly moved to the location of an

emergency and turned on.


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Figure 2. Moving toward smaller form factors and a compact base station architecture

The value proposition of compact base stations

Compact base stations profoundly change the value proposition of microcells and picocells to service

providers. They make microcells and picocells cost-effective for much larger deployments, and provide a

clear cost and performance advantage over ground-based or distributed macro base stations in high-

capacity deployments.

After building the initial macro network, service providers can use compact base stations to take 4G

right where they need it, when they need it. As they move subscribers to their new 4G networks or sign

up new ones, they will identify locations where additional capacity is needed, and place compact base

stations there. Instead of wide-area RF planning, they can focus on ad-hoc deployment plans around

well-defined areas with high demand.

Increasingly, however, microcells and picocells are likely to become an integral part of network planning

in early deployment phases of network planning and deployment.

The smaller footprint and reduced power consumption have a major impact on the cost structure (Table

3). While the base station hardware costs less, the biggest savings to service providers come from the

avoidance of ground shelters and ventilation systems, a more streamlined installation, and lower

recurring rental costs.

In addition to a favorable total cost of ownership (TCO) in comparison to ground-based and distributedbase stations, compact base stations give wireless service providers an unprecedented flexibility that

shortens the time to market. With the many options for where to mount compact base stations,

permitting requirements are typically reduced, because there is no need to build new infrastructure to

install the hardware. Low power consumption makes it possible to deploy base stations rapidly in under-

served rural areas where electricity and wireline broadband connections are not available. A simpler

installation leads to faster deployments and quicker training for installation staff.


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Table 3. The CAPEX and OPEX advantages of compact cells

Interphases application-ready 4G module for compact eNodeB base stations

To meet the demand from 4G service providers for flexible, high-capacity, dense deployments,

Interphase has developed an application-ready compact eNodeB module that can fit multiple form

factors, such as a card or a blade for the Advanced Telecommunications Computing Architecture

(AdvancedTCA) or MicroTCA chassis, as well as a zero-footprint card or customized design (Figure 3).

The eNodeB module comes with integrated application-ready software: pre-integrated, fully compliant

L1L3 LTE protocol layers, management tools, and third-generation Interphase iWARE application

programming interface (API). This allows vendors to develop a complete product line that addresses the

needs of different markets, using a single development platform and thus accelerating productavailability and minimizing development costs.

The module is compatible with leading EPC vendors, and supports optional clocking and global

positioning system (GPS) options that enable the modules use in non-stationary deployment scenarios.

When deployed in a single-card configuration, such as that for zero-footprint designs, it can be powered

by a CAT-5 cable, an IEEE 802.3at PoE connection, or even solar power, thus removing the need for

expensive power distribution to remote cell sites.

Figure 3. Interphases flexiblecompact LTE base station module: form factors

Feature CAPEX savings OPEX savings

Small footprint and weight

Lower cost for base stations

No need for expensive coax cables

Faster, lower-cost installation Lower site rental due to smaller

footprint and ability to install base

stations in low-cost locationsNo need for ground

equipment

Ground shelter and active cooling unit

not needed

Faster, lower-cost installation

Low power consumption Lower recurring electricity bills

High-density network

More efficient spectrum usage,

allowing higher financial return on

spectrum assets


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The flexible Interphase LTE base station module provides a compelling proposition for vendors:

Low development costs and short time to market. The module is a turnkey, application-ready

platform that includes the control processor, baseband, storage, and switch, along with pre-

integrated LTE eNodeB L1L3 LTE protocol layers and Interphases 3rd generation iWARE API. The

modular approach facilitates the development of specific applications, and offers flexibility in choice

of the desired radio and overall vendor packaging.Minimized footprint and low power consumption, coupled with advanced performance. The

reduced size and weight (less than 500 g), low power consumption (26 W), and high performance

(up to three LTE frequency-division duplexing [LTE-FDD] or time-division LTE [TD-LTE] sectors with

20MHz and 2x2 MIMO) are enabled by a SoC architecture that includes base station control,

baseband, and the radio interface.

Multiple form factors. The base station uses a modular, software-defined architecture that is highly

scalable and facilitates the development of multiple form factors, from femtocell to microcell, using

the underlying technology and API interface. Interphases in-house engineering design team has the

extensive wireless design expertise needed to customize this solution to meet specific vendor

specifications and their tight time-to-market deadlines.

Commercial off-the-shelf (COTS) version available. The iSPAN 36701 Advanced Mezzanine Card(AMC)provides off-the-shelf simplicity and flexibility, as well as cost efficiencies in product

development, demonstration unit preparation, and ATCA or MicroTCA base station deployments.

Standards and common interfaces supported.iSPAN modules support multiple standards-based

and common interfaces (common public radio interface [CPRI], RJ45, Ethernet, Serial RapidIO, and

Peripheral Component Interconnect [PCI] Express) to give mobile service providers more flexibility in

their deployments.

Conclusion

The topology of wireless networks is rapidly evolving to meet the need to transport much larger

volumes of data traffic, to keep the per-bit costs at a minimum, and to extract the maximum

performance from new, computationally-intensive 4G interfaces such as LTE. Deploying a larger number

of traditional base stations that require actively cooled ground equipment is a solution that is too

expensive, and that fails to the deliver the spectrum efficiency, capacity density, and coverage that

wireless service providers need in their 4G deployments.

Compact base stations have been designed to meet these challenges. This new base station architecture

is ideally suited for dense, high-capacity deployments in urban areas, for vertical applications, and for

cost-effective wide-area coverage in underserved areas. Their small footprint and low power

consumption allow service providers to reduce their CAPEX and OPEX, while retaining the advanced

performance of 4G technologies.

The new Interphase LTE eNodeB module is an application-ready solution that provides vendors with the

benefits of compact base stations. It gives vendors a single underlying software and hardware platform

to develop 4G base stations with appropriate form factors and services, for a range of small and large

base station markets in a flexible and cost-efficient way. With the Interphase eNodeB module, service

providers have the freedom to take LTE where they need it.


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Copyright 2010 Interphase Corporation. All rights reserved. Interphase, the Interphase logo, and iSPAN are trademarks or

registered trademarks of Interphase. All other trademarks are the property of their respective owners. Interphase accepts no

responsibility for the accuracy of this document and may change it at any time.

Interphase Corporation

2901 N. Dallas Parkway

Plano, Texas 75093

USA

Toll Free: (800) 327-8638

Phone: +1 (214) 654-5000

www.iphase.com

About Interphase Corporation

Interphase Corporation (NASDAQ: INPH) delivers solutions for LTE and WiMAX,

interworking gateways, packet processing, network connectivity, and security

for key applications for the Communications, Aerospace-Defense, and

Enterprise markets. Founded in 1974, Interphase provides expert Engineering

Design and Contract Manufacturing services, in addition to its COTS portfolio.
http://www.iphase.com/http://www.iphase.com/http://www.iphase.com/

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