Showing posts with label Backhaul. Show all posts
Showing posts with label Backhaul. Show all posts

Wednesday, 10 October 2012

Small Cell Backhaul Solution Types

This is from a presentation by Julius Robson of CBNL, representing NGMN in the Cambridge Wireless Small Cells SIG event.
Interesting to see all possible options for Backhaul for small cells.

The presentation is available to view and download from here.

Related blog posts:


Monday, 18 June 2012

3GPP Release-12 and beyond


3GPP Recently held a workshop on "Release 12 and Onward" to identify common requirements for future 3GPP radio access technologies. The goal of the workshop is to investigate what are the main changes that could be brought forward to evolve RAN toward Release 12 and onward. It is recommended that presentations in the workshop include views on:
- Requirements
- Potential technologies
- Technology roadmap for Releases 12, 13 and after

The discussions from the workshop should be used to define the work plan for Release 12 and onward in TSG-RAN.

The list of presentations and links, etc. are below and I have also embedded the Summary and Draft report, both of which can be downloaded from 3GPP website or slideshare. Here is a list of different topics and the presentations that covered them:


AdHoc Networks
AdHoc Networks - RWS-120035


Antennas, Beamforming, Transmitters, Receivers
3D-beamforming - RWS-120002
Vertical sectorization/3D beamforming via AAS - RWS-120005
Advanced receivers and joint Tx/Rx optimisation - RWS-120005
Network assistance for IC receivers - RWS-120005
Support of Active Antenna Systems - RWS-120006
Advanced transmitter beamforming - RWS-120010
Advanced receiver cancellation - RWS-120010
Vertical and 3D beamforming - RWS-120011
MIMO Enhancements - RWS-120014
New antenna configurations and 3D MIMO - RWS-120014
UE AAS (Active Antenna System) [Detailed] - RWS-120015 / RWS-120049
Cloud of Antennas (CoA) Concept - RWS-120016
Support of Massive MIMO Technology - RWS-120016
Full Dimension MIMO (FD-MIMO) System [Detailed] - RWS-120021 / RWS-120046
Cloud-RAN: Benefits and Drawbacks - RWS-120021 / RWS-120046
Further Enhanced Receivers - RWS-120022
Multiple antenna evolution - RWS-120025
3D beamforming - RWS-120026
Vision of 3D MIMO - RWS-120029
Massive MIMO & 3D MIMO - RWS-120034
Potential MIMO Enhancements - RWS-120035
Advanced Antenna Technology - RWS-120035
DL MIMO Enhancement - RWS-120037
Performance Requirement for 8Rx at eNB - RWS-120037
UE Receiver Enhancements - RWS-120039
DL MU-MIMO Enhancement - RWS-120039
Enhancement of MIMO, CoMP - RWS-120040
Advanced MIMO - RWS-120040
MIMO and COMP - RWS-120041
Role of Advanced Receivers - RWS-120041
Advanced Interference Handling - RWS-120041
Interference Suppression Subframes (ISS) and IRC Receiver [Detailed] - RWS-120051


Applications (Apps)
Efficiency for diverse small data applications - RWS-120011
Device Service/Application Awareness - RWS-120018
I-Net:”I”-centric mobile network design philosophy - RWS-120024
Application Aware Comm - RWS-120036 / RWS-120050


Backhaul and Relay
Relay backhaul enhancement - RWS-120011
LTE Backhaul - RWS-120013
Relay - RWS-120025
CoMP, backhaul and X2 interface - RWS-120027 / RWS-120048
Mobile Relay And Relay Backhaul Enhancement - RWS-120029


Baseband
Baseband resource pooling and virtualization - RWS-120011


Capacity and Coverage
Higher system capacity - RWS-120010
Capacity for Mobile Broadband: Requirements and Candidate technologies - RWS-120012
Increase N/W capacity by 1000 times - RWS-120020
Coverage Enhancement - RWS-120037
Capacity Enhancement - RWS-120038 / RWS-120047
Cell-edge Throughput Improvement - RWS-120038 / RWS-120047


Carrier Aggregation, Flexible Bandwidths and Multiflow
LTE multiflow / Inter-site CA - RWS-120002
LTE/HSDPA Carrier Aggregation - RWS-120002
Multiflow Enhancements - RWS-120002
Multi-Stream Aggregation - RWS-120006
Provide mechanisms for Flexible Bandwidth Exploitation - RWS-120008
Carrier aggregation enhancement - RWS-120019
Inter-eNB Carrier Aggregation - RWS-120021 / RWS-120046
Evolution of Carrier Aggregation - RWS-120036 / RWS-120050
CA of Alternative Spectra - RWS-120042


Cells, Carriers, C/U Planes
C/U plane split & Phantom cell - RWS-120010
Phantom cell by single/separate nodes - RWS-120010
Phantom cell: Other topics - RWS-120010
New Carrier Type for Primary Component Carrier - RWS-120011
Flexible/Reconfigurable Cells - RWS-120023
New carrier-type (NCT) enhancements - RWS-120026
Amorphous cells - RWS-120034
New Carrier Types - RWS-120035
Non-Orthogonal Access - RWS-120039
Dynamic Area Construction for UE - RWS-120040


Cognitive Radio
Cognitive radio - RWS-120034
Cognitive Networking - RWS-120036 / RWS-120050


Coordinated MultiPoint (CoMP)
CoMP Enhancements - RWS-120014
CoMP/ICIC enhancement - RWS-120019
CoMP Enhancements - RWS-120023
CoMP enhancements - RWS-120026
CoMP Technologies - RWS-120027 / RWS-120048
Enhanced CoMP - RWS-120029
Potential CoMP Enhancements - RWS-120035
CoMP - RWS-120037
CoMP Enhancement for Indoor Environment - RWS-120040
Overhauling DL CoMP - RWS-120042


Device, Handsets, UE's
Additional UE Enhancements - RWS-120018
Coordination : Multi-mode UE - RWS-120024


D2D / Device-to-Device
Device-to-Device - RWS-120003
LTE Device to Device - Proximity Based Services - RWS-120004
LTE device to device - RWS-120007
LTE direct communication - RWS-120007
Device-to-Device Communications - RWS-120014
D2D Discovery/Communication - RWS-120016
3GPP Proximity Services (ProSe) / D2D - RWS-120022
Device-to-Device communications - RWS-120026
Device-to-Device communication - RWS-120036 / RWS-120050


Data Rates and Throughputs
Higher data rate and user-experienced throughput - RWS-120010
Fairness of user throughput - RWS-120010


Deployments
LTE in Local Area Deployments & Enhancements - RWS-120004
Energy Efficient Local Area Deployments - RWS-120004
Scaling for Mass Deployment - RWS-120008
Flexible and cost-efficient NW deployments - RWS-120010
Considerations on dense NW deployment - RWS-120019


Energy Consumption, Efficiency and Savings
Energy efficiency - RWS-120005
Reduce energy consumption - RWS-120008
Energy Saving - RWS-120014
UE Power Saving - RWS-120036 / RWS-120050
NB Power Saving - RWS-120036 / RWS-120050
Energy Saving Enhancements with CoMP - RWS-120040
Energy Saving with Centralized eNB - RWS-120040


Herogeneous Networks (HetNets)
Optimisation of Het Nets performance - RWS-120005
Improved Support for Heterogeneous Networks - RWS-120006
Network hyper-densification: LTE HetNet2.0 - RWS-120007
Multi-layer HetNet Deployments - RWS-120016
HetNet for HSPA - RWS-120017
HetNet Enhancements - RWS-120023
HetNet Mobility - RWS-120029
Small cells & HetNet - RWS-120031
HetNet - RWS-120037
HetNet Enhancements for HeNB - RWS-120040


HSDPA / HSUPA / HSPA+ Enhancements
HSPA UL Enhancements - RWS-120003
Uplink Enhancements - RWS-120006
UMTS evolution: enhancing CS voice on DCH - RWS-120007
High Speed Packet Access - RWS-120012
HSPA RRM enhancement - RWS-120024
HSPA+ further evolution - RWS-120034


Interworking (HSPA, LTE)
Coordination : HSPA/LTE e-interworking - RWS-120024
Inter-RAT Coordination/CA - RWS-120037


Local-Area Access (Small Cells)
Local-Area Access - RWS-120003
LTE in Local Area Deployments & Enhancements - RWS-120004
LTE Local Area Enhancements - RWS-120004
LTE Local Area Enhancement Areas - RWS-120004
enhanced Local Area (eLA) - RWS-120010
Local Area Enhancements - RWS-120022
Improved Local Area Mobility - RWS-120022


LTE
LTE for Nomadic and Fixed Use - RWS-120018
E-PDCCH enhancement - RWS-120019
Efficiency : Paging Optimization - RWS-120024


LTE Hotspot and Indoor Enhancements (LTE-Hi)
Hotspot and Indoor Enhancements (LTE-Hi) - RWS-120006
Hotspot/indoor Scenario (LTE-Hi) - RWS-120025
Indoor & Hotspot Enhancements (LTE-Hi) [Detailed] - RWS-120029
Possible Study Items for Indoor Environment - RWS-120040


M2M / Machine Type Communications (MTC)
Machine Type Communications - RWS-120003
Improved Support for MTC - RWS-120006
Machine-to-Machine: The Internet of Things - RWS-120014
Machine Type Communications: a new ecosystem - RWS-120014
Wireless MTC and RAN optimizations for MTC - RWS-120016
Low-Cost MTC UE - RWS-120017
MTC + eDDA (enhanced Diverse data application) - RWS-120019
Further Enhancements to Support MTC - RWS-120023
MTC - RWS-120025
MTC enhancements - RWS-120026
M2M - RWS-120029
MTC and migration of traffic from 2G - RWS-120031
Machine Type Communications enhancements - RWS-120034
Machine Type Communications - RWS-120035
Extension triggered by growing M2M traffic - RWS-120038 / RWS-120047
LTE-based M2M - RWS-120041


MBMS / eMBMS
eMBMS Enhancements - RWS-120007
eMBMS - RWS-120013
UHD Multimedia Broadcast/Multicast Service - RWS-120036 / RWS-120050


Mesh Networks
Mesh Networks - RWS-120018


Network Density
Network density: Scenarios - RWS-120010


Network Architecture and Operation
Easier network operation, tolerance to failure - RWS-120005
System Architecture - RWS-120032
Evolution of LTE Networks - RWS-120034


Positioning
Positioning Enhancements - RWS-120006


Public Safety
Public Safety - RWS-120030
Operation of Public Safety System via LTE - RWS-120031
Public safety’s future in LTE [Detailed] - RWS-120033


Self Organising Networks (SON) and Minimisation of Drive Testing (MDT)
SON Evolution - RWS-120002
Enhanced MDT - RWS-120011
Network Self-Optimisation - RWS-120014
SON and MDT - RWS-120017
HetNet SON - RWS-120029
MDT & Energy Saving - RWS-120029
Autonomous Interference Coordination - RWS-120029
Large scale multi-layer centralized cooperative radio - RWS-120034
MDT Enhancement - RWS-120036 / RWS-120050
SON Enhancements - RWS-120036 / RWS-120050
MDT and eDDA - RWS-120041


Small Cells (HNB/HeNB)
UMTS evolution: small cells - RWS-120007
Wide & Local area enhancements - RWS-120010
Small Cells - RWS-120014
Small Cell Enhancement in Rel-12 - RWS-120021 / RWS-120046
HeNB Enhancement - RWS-120036 / RWS-120050
Efficient Usage of Macro and Small Cells - RWS-120038 / RWS-120047
Low-cost Low Power Nodes (LC-LPN) - RWS-120038 / RWS-120047
Small-Cell Improvements: System Aspects - RWS-120041


Spectrum
Enhanced spectrum efficiency - RWS-120005
Spectrum efficiency: eLA topics - RWS-120010
Scenarios for spectrum extension - RWS-120010
Spectrum and spectrum usage - RWS-120012
Wider Spectrum Utilization - RWS-120016
Spectral efficiency for LTE - RWS-120017
New Spectrum for Mobile Broadband Access - RWS-120021 / RWS-120046
Enabling Technologies for New Spectrum - RWS-120021 / RWS-120046
Radio Propagation - RWS-120021 / RWS-120046
Opportunistic Use of Unlicensed Spectrum for D2D Local Traffic - RWS-120023
Flexible Spectrum Utilization - RWS-120024
Spectrum Related: New Bands And CA Band Combinations - RWS-120029
Spectrum - RWS-120032
Hybrid access scheme - RWS-120034
Spectrum - RWS-120035
Spectrum and Transmission Efficiency - RWS-120039
Spectrum-Agile LTE - RWS-120041


TDD / TD-LTE
TD-LTE - RWS-120014
TDD-specific aspects - RWS-120014
TDD adaptive reconfiguration - RWS-120034
Efficient Usage of Dual Duplex Modes - RWS-120038 / RWS-120047
LTE TDD Small-Cell versus WiFi - RWS-120041


Testing
Testing and Certification - RWS-120022


Traffic and Signalling Overhead
Efficient support of diverse traffic characteristics - RWS-120005
Efficient support for variety of traffic types - RWS-120010
Enhancements for variety of traffic types - RWS-120010
Very high traffic (and signalling) scenarios - RWS-120017
Control Plane Overhead Reduction - RWS-120021 / RWS-120046
Further Enhancements to Support Diverse Data Applications - RWS-120023
Efficiency : Small data services in high mobility - RWS-120024


User Experience
Improve User experience - RWS-120009
User Challenges - RWS-120032


Video streaming, call
RAN Enhancements for Video Streaming QoE - RWS-120023
RAN Enhancements for Internet Video Call - RWS-120023


WiFi / WLAN
Cooperation between LTE/HSPA and WiFi - RWS-120005
Unlicensed spectrum: LTE & WLAN - RWS-120007
LTE integration with other RATs - RWS-120014
WiFi integration: For Beyond Rel-12 - RWS-120017
LTE-WLAN Interworking - RWS-120023
Coordination With WiFi - RWS-120029
Smarter opportunistic usage of Wi-Fi - RWS-120031
LTE TDD Small-Cell versus WiFi - RWS-120041


Others
Other identified techniques for LTE - RWS-120005
Efficient Transactions - RWS-120035
Link Enhancement Considerations - RWS-120035
Intra-RAT cooperation / Inter-RAT cooperation - RWS-120036 / RWS-120050


Here is the summary from the workshop:

Complete list of Presentations

RWS-120002Release 12 and beyond for C^4 (Cost, Coverage, Coordination with small cells and Capacity)NSN
RWS-120003Views on Rel-12Ericsson & ST-Ericsson
RWS-120004LTE evolving towards Local Area in Release 12 and beyondNokia Corporation
RWS-120005Views on Release 12Orange
RWS-120006Views on Rel-12 and onwards for LTE and UMTSHuawei Technologies, HiSilicon
RWS-1200073GPP RAN Rel-12 & BeyondQualcomm
RWS-120008New Solutions for New Mobile Broadband ScenariosTelefonica
RWS-120009Telecom Italia requirements on 3GPP evolutionTelecom Italia
RWS-120010Requirements, Candidate Solutions & Technology Roadmap for LTE Rel-12 OnwardNTT DOCOMO, INC.
RWS-120011Where to improve Rel-12 and beyond: Promising technologiesNEC
RWS-120012Deutsche Telekom Requirements and Candidate TechnologiesDeutsche Telekom
RWS-120013Release 12 Prioritization ConceptsDish Networks
RWS-120014Towards LTE RAN EvolutionAlcatel-Lucent
RWS-120015UE AAS (Active Antenna System)Magnolia Broadband
RWS-120016Requirements and Technical Considerations for RAN Rel.12 & OnwardsFujitsu Limited
RWS-120017Operator requirements on future RAN functionalityTeliaSonera
RWS-120018AT&T View of Release 12 in the North America MarketplaceAT&T
RWS-120019Major drivers, requirements and technology proposals for LTE Rel-12 OnwardPanasonic
RWS-120020Efficient spectrum resource usage for next-generation N/WSK Telecom
RWS-120021Technologies for Rel-12 and onwardsSamsung Electronics
RWS-120022LTE Rel-12 and BeyondRenesas Mobile Europe
RWS-120023LTE Rel-12 and Beyond: Requirements and Technology ComponentsIntel
RWS-120024Considerations on further enhancement and evolution of UMTS/LTE network in R12 and onwardsChina Unicom
RWS-120025Views on LTE R12 and BeyondCATT
RWS-120026A proposal for potential technologies for Release 12 and onwardsETRI
RWS-120027A view on requirements on Rel-12 and onwards from an operator’s viewpointSoftbank Mobile
RWS-120028India market Requirements for Rel. 12 and beyondCEWiT
RWS-120029Views on LTE Rel-12 & BeyondCMCC
RWS-120030LTE addressing the needs of the Public Safety CommunityIPWireless
RWS-120031Vodafone view on 3GPP RAN Release 12 and beyondVodafone
RWS-120032An Operator’s View of Release 12 and BeyondSprint
RWS-120033Public Safety Requirements for Long Term Evolution REL-12U.S. Department of Commerce
RWS-120034Views on 3GPP Rel-12 and BeyondZTE
RWS-120035Considerations for LTE Rel-12 and beyondMotorola Mobility
RWS-120036LG’s view on evolution of LTE in Release 12 and beyondLG Electronics
RWS-120037Views on REL-12 and OnwardsChina Telecom
RWS-120038KDDI’s Views on LTE Release 12 onwardsKDDI
RWS-120039Evolving RAN Towards Rel-12 and BeyondSHARP
RWS-120040Views on enhancement of system capacity and energy efficiency toward Release12 and onwardHitachi
RWS-120041Beyond LTE-A: MediaTek’s view on R12MediaTek
RWS-120042Potential Technologies and Road Map for LTE Release 12 and BeyondITRI, HTC
RWS-120043New concept to maximize the benefit of interference rejection at the UE receiver: interference suppression subframes (ISS)Broadcom
RWS-120046Technologies for Rel-12 and onwardsSamsung Electronics
RWS-120047KDDI’s Views on LTE Release 12 onwardsKDDI
RWS-120048A view on Rel-12 and onwards from an operator’s viewpointSoftbank Mobile
RWS-120049UE AAS (Active Antenna System)Magnolia Broadband
RWS-120050LG’s view on evolution of LTE in Release 12 and beyondLG Electronics
RWS-120051New concept to maximize the benefit of interference rejection at the UE receiver: interference suppression subframes (ISS)Broadcom

More technically minded people want to explore the 3GPP website for the workshop links here: http://3gpp.org/ftp/workshop/2012-06-11_12_RAN_REL12/

Draft report that gives more insight into the presentations as follows:


Saturday, 19 May 2012

Backhauling the Telefonica O2 London LTE Trial

Interesting Video and Presentation about backhaul in the London Trial of LTE deployment by O2.


Presentation:
We have an event in October in Cambridge Wireless that will look at the backhaul and deployments a bit more in detail. Details here.

Sunday, 20 November 2011

Do we need Fiber?


Click on the image to view full size


From a presentation by Acreo, available here.

Thursday, 27 October 2011

Femtocell Backhaul Options


Any others?

There is also this interesting presentation from Maravedis on Non-Line-of-Sight (NLoS) backhaul, embedded below:

Friday, 30 September 2011

Macrocells or Metrocells?

Just went through Alcatel-Lucent strategic paper on whether to go for more Macrocell sites or rather have Metrocells instead.

A good description of Metrocells is available in the document:

Metro cells, the latest evolution in small cells, are based on the same low cost femtocell technology that has been successfully used in home and enterprise cells, but with enhanced capacity and coverage. With higher processing and transmit power, the first generation of metro cells is engineered to serve from 16 to 32 users and provide a coverage range from less than 100 meters in dense urban locations to several hundred meters in rural environments. However, unlike home and enterprise cells, metro cells are owned and managed by a MSP and typically used in public or open access areas to augment the capacity or coverage of a larger macro network.

Available in both indoor and outdoor versions, metro cells are plug-and-play devices that use Self-Organizing Network (SON) technology to automate network configuration and optimization, significantly reducing network planning, deployment and maintenance costs. While indoor versions use an existing broadband connection to backhaul traffic to a core network, outdoor versions may be opportunistically deployed to take advantage of existing wireline or wireless sites and backhaul infrastructure, such as Fiber-to-the-Node (FTTN), Fiber-to-the-Home (FTTH), Very-high-speed Digital Subscriber Line (VDSL) street cabinets, and DSL backbone.

Since metro cells use licensed spectrum and are part of the MSP’s larger mobility network, they provide the same trusted security and quality of service (QoS) as the macro network. With seamless handovers, users can roam from metro cells to the macro network and vice versa. Metro cells also deliver the same services as the macro network (for example, voice, Short Message Service (SMS), and multimedia services), and support application programming interfaces (APIs), that may be used for developing new, innovative services. In short, metro cells promise to be the ideal small cells for network offloading.

For more details on the whitepaper see: http://www.slideshare.net/zahidtg/metro-cells-whitepaper



Friday, 26 August 2011

Two interesting NGMN papers on Backhaul

There are some interesting blog posts on Broadband Traffic Managemenet on Backhaul. Here are few excerpts:

Traditional network management practice says that network element usage level should not exceed 70% of its capacity. If it does - it is time to do something - buy more or manage it better. So, according to a recent Credit Suisse report - it is time to do something for wireless networks, globally. For North America, where current utilization at peak time reaches 80% it is even urgent.

Phil Goldstein (pictured) reports to FierceWireless that - "Wireless networks in the United States are operating at 80 percent of total capacity, the highest of any region in the world, according to a report prepared by investment bank Credit Suisse. The firm argued that wireless carriers likely will need to increase their spending on infrastructure to meet users' growing demands for mobile data .. globally, average peak network utilization rates are at 65 percent, and that peak network utilization levels will reach 70 percent within the next year. .. 23 percent of base stations globally have capacity constraints, or utilization rates of more than 80 to 85 percent in busy hours, up from 20 percent last year .. In the United States, the percentage of base stations with capacity constraints is 38 percent, up from 26 percent in 2010"

And

The Yankee Group provides the following forecast for mobile backhaul:
Average macrocell backhaul requirements were 10 Mbps in 2008 (seven T1s, five E1s). In less than three years, they have more than tripled to 35 Mbps in 2011, and by 2015, Yankee Group predicts they will demand 100 Mbps.
There were 2.4 million macro cell site backhaul connections worldwide in 2010, growing to 3.3 million by [2015?]
Yankee's new research conclude:

"The market for wholesale backhaul services in North America will grow from $2.45 billion in 2010 to $3.9 billion in 2015, with the majority of this growth coming from Ethernet backhaul. Successful backhaul service providers will be those that can demonstrate price/performance and reliability, have software tools in place and can meet the specific needs of the mobile market.

And recently:

A Dell'Oro Group report forecasts that "Mobile Backhaul market revenues are expected to approach $9B by 2015. This updated report tracks two key market segments: Transport, which includes microwave and optical equipment, and Routers and Switches, which includes cell site devices, carrier Ethernet switches, and service provider edge routers .. routers and switches expected to constitute 30% of mobile backhaul market "

Shin Umeda, Vice President of Routers research at Dell’Oro Group said: “Our research has found that operators around the world are concerned with the rate of mobile traffic growth and are transitioning to Internet Protocol (IP) technologies to build a more efficient and scalable backhaul network. Our latest report forecasts the demand for IP-based routers and switches will continue to grow through 2015, almost doubling the market size of the Router and Switches segment in the five-year forecast period”

I have some basic posts on why Backhaul is important, here and here.

NGMN has timely released couple of whitepapers on the Backhaul.

The first one, 'Guidelines for LTE Backhaul Traffic Estimation' document describes how a model is developed to predict traffic levels in transport networks used to backhaul LTE eNodeBs. Backhaul traffic is made up of a number of different components of which user plane data is the largest, comprising around 80-90% of overall traffic, slightly less when IPsec encryption is added. These results reveal that the cell throughput characteristics for data carrying networks are quite different to those of voice carrying networks.

The purpose of second one, 'NGMN Whitepaper LTE Backhauling Deployment Scenarios' is to support operators in their migration from current architectures to new, packet-based backhaul networks. With the introduction of LTE operators need to look at how the backhauling network, the network domain that connects evolved NodeBs (eNBs) to MME and S/P-GW, is capable of adapting to the new requirements, namely the adoption of a packet infrastructure, without disrupting the existing services. This paper introduces some reference architectures, moving from a pure layer 2 topology to a full layer 3 one, discussing some elements to be considered in the design process of a network.

They are both long but interesting read if you like to learn more about Backhaul and the best way in future proofing the network deployments.

Saturday, 30 July 2011

Tuesday, 14 December 2010

What are Heterogeneous Networks (HetNets)?

HetNets are hot. I hear about them in various contexts. Its difficult to find exactly what they are and how they will work though. There is a HetNets special issue in IEEE Communications Magazine coming out next year but that's far away.

I found an interesting summary on HetNets in Motorola Ezine that is reproduced below:


“The bigger the cell site, the less capacity per person you have,” said Peter Jarich, research director with market intelligence firm Current Analysis. “If you shrink coverage to a couple of blocks, you are having that capacity shared with a fewer number of people, resulting in higher capacity and faster data speeds.”

This is a topic the international standards body, the Third Generation Partnership Project (3GPP), has been focusing on to make small cells part of the overall cellular network architecture.

“What we’re seeing is a natural progression of how the industry is going to be addressing some of these capacity concerns,” said Joe Pedziwiatr, network systems architect with Motorola. “There is a need to address the next step of capacity and coverage by introducing and embracing the concepts of small cells and even looking at further advances such as better use of the spectrum itself.”

As such, discussion regarding this small-cell concept has emerged into what is called heterogeneous networks, or Het-Net, for short. The idea is to have a macro wireless network cooperating with intelligent pico cells deployed by operators to work together within the macro network and significantly improve coverage and augment overall network capacity. Small cells can also be leveraged to improve coverage and deliver capacity inside buildings. Indoor coverage has long been the bane of mobile operators. Some mobile operators are already leveraging this concept, augmenting their cellular service offering with WiFi access to their subscriber base in order to address the in-building coverage and capacity challenges facing today’s cellular solutions.

Pedziwiatr said this Het-Net structure goes far beyond what is envisioned for femtocells or standard pico cells for that matter. Introducing a pico cell into the macro network will address but just one aspect of network congestion, namely air interface congestion. The backhaul transport network may become the next bottleneck. Finally, if all this traffic hits the core network, the congestion will just have shifted from the edge to the core.

“This requires a system focus across all aspects of planning and engineering,” Pedziwiatr said. “We’re trying to say it goes beyond that of a femto. If someone shows up at an operator and presents a pico cell, that is just one percent of what would be needed to provide true capacity relief for the macro network.”

Femtocells, otherwise known as miniature take-home base stations, are obtained by end users and plugged into a home or office broadband connection to boost network signals inside buildings. A handful of 3G operators worldwide are selling femtocells as a network coverage play. For the LTE market, the Femtocell Forum is working to convince operators of the value of a femtocell when it comes to better signal penetration inside buildings and delivering high-bandwidth services without loading the mobile network. This is possible, because the backhaul traffic runs over the fixed line connection. However, this femtocell proposition largely relies on end user uptake of them—not necessarily where operators need them, unless they install femtocells themselves or give end users incentives to acquire them.

As with any new concept, there are challenges to overcome before Het-Nets can become reality. Het-Nets must come to market with a total cost of ownership that is competitive for an operator to realize the benefit of providing better capacity, higher data speeds, and most of all, a better end-user experience said Chevli.

“The level of total cost of ownership has to be reduced. That is where the challenge is for vendors to ensure that any new solution revalidates every existing tenet of cellular topology and evolve it to the new paradigm being proposed,” Chevli said. “You can’t increase the number of end nodes by 25X and expect to operate or manage this new network with legacy O&M paradigms and a legacy backhaul approach.”

One of the issues is dealing with interference and Het-Net network traffic policies. “How do you manage all of these small cell networks within the macrocell network?” asked Jarich. “Right now if you have a bunch of femtocells inside a house, there is this concept that the walls stop the macrocell signals from getting in and out. You get a separation between the two. Go outdoors with small cells underlying bigger cells and you get a lot more interference and hand-off issues because devices will switch back and forth based on where the stronger signal is.”

Pedziwiatr said for a Het-Net to work, it would require a change in node management, whereby an operator isn’t burdened with managing big clusters of small cells on an individual basis. “We see elements of SON (self organizing networks), self discovery and auto optimization that will have to be key ingredients in these networks. Otherwise operators can’t manage them and the business case will be a lot less attractive,” he said.

Fortunately, the industry has already been working with and implementing concepts of SON in LTE network solutions. In the femtocell arena also, vendors have been incorporating some elements and concepts of SON so that installing them is a plug-and-play action that automatically configures the device and avoids interference. But even then, Het-Nets will require further SON enhancement to deal with new use cases, such as overlay (macro deployment) to underlay (pico deployments) mobility optimization.

When it comes to LTE, SON features are built into the standard, and are designed to offer the dual benefit of reducing operating costs while optimizing performance. SONs will do this by automating many of the manual processes used when deploying a network to reduce costs and help operators commercialize their new services faster. SON will also automate many routine, repetitive tasks involved in day-to-day network operations and management such as neighbor list discovery and management.

Other key sticking points are deployment and backhaul costs. If operators are to deploy many small cells in a given area, deploying them and backhauling their traffic should not become monumental tasks.

Chevli and Pedziwiatr envision Het-Nets being deployed initially in hot zone areas – where data traffic is the highest – using street-level plug-and-play nodes that can be easily installed by people with little technical know-how.

“Today, macro site selection, engineering, propagation analysis, rollout and optimization are long and expensive processes, which must change so that installers keep inventories of these units in their trucks, making rollout simple installations and power-ups,” said Pedziwiatr. “These will be maintained at a minimum with quick optimization.”

The notion of backhauling traffic coming from a large cluster of Het-Net nodes could also stymie Het-Nets altogether. Chevli said that in order to keep costs down, Het-Net backhaul needs to be a mix of cost-effective wireless or wired backhaul technology to aggregate traffic from what likely will be nodes sitting on lamp posts, walls, in-building and other similar structures. The goal then is to find a backhaul point of presence to aggregate the traffic and then put that traffic on an open transport network in the area.

Backhaul cost reductions may also be a matter of finding ways to reduce the amount of backhaul forwarded to the core network, Pedziwiatr said. These types of solutions are already being developed in the 3G world to cope with the massive data traffic that is beginning to crush networks. For traffic such as Internet traffic, which doesn’t need to travel through an operator’s core network, offloading that traffic as close to the source as possible would further drive down the cost of operation through the reduction of backhaul and capacity needs of the core network.

In the end, with operators incorporating smaller cells as an underlay to their macro network layer rather than relying on data offloading techniques such as femtocells and WiFi that largely depend on the actions of subscribers and impacted by the surrounding cell operating in the same unlicensed frequency, Het-Nets in licensed spectrum will soon become the keystone in attacking the ever-present congestion issue that widely plagues big cities and this is only likely to get worse over time.

Image Source: Dr. Daichi Imamura, Panasonic presentation.