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Showing posts with label Deployment. Show all posts
Showing posts with label Deployment. Show all posts

Saturday, 26 April 2014

LTE Deployment Dilemma


Earlier this month during our Cambridge Wireless Small Cells SIG event, I presented a small quiz in the final session. The first part of the quiz was titled "LTE Deployment Dilemma" and it generated lots of interesting discussions. After the event, I did a more detailed writeup of that and Cisco has kindly published it in their SP Mobility Blog. Since many people have told me that they cannot anonymously post comments there, I am now bringing it to this blog. I am interested in hearing what others think.

Here is the complete post



Thursday, 3 October 2013

Case study of SKT deployment using the C-RAN architecture


Recently I came across this whitepaper by iGR, where they have done a case study on the SKT deployment using C-RAN. The main point can be summarised from the whitepaper as follows:

This approach created several advantages for SK Telecom – or for any operator that might implement a similar solution – including the:

  • Maximum re-use of existing fiber infrastructure to reduce the need for new fiber runs which ultimately reduced the time to market and capital costs.
  • Ability to quickly add more ONTs to the fiber rings so as to support additional RAN capacity when needed.
  • Support of multiple small cells on a single fiber strand. This is critical to reducing costs and having the flexibility to scale.
  • Reduction of operating expenses.
  • Increased reliability due to the use of fiber rings with redundancy.
  • Support for both licensed and unlicensed RAN solutions, including WiFi. Thus, the fronthaul architecture could support LTE and WiFi RANs on the same system.
As a result of its implementation, SK Telecom rolled out a new LTE network in 12 months rather than 24 and reduced operating expenses in the first year by approximately five percent. By 2014, SK Telecom expects an additional 50 percent OpEx savings due to the new architecture.

Anyway, the paper is embedded below for your perusal and is available to download from the iGR website here.



Friday, 9 November 2012

Virgin Media's offering on SCaaS

I have blogged about FaaS in the past that is now undergoing trials. I also blogged about SCaaS from our last Cambridge Wireless event that shows the seperation between the operator and the services provided by Small Cell service provider. In the recent Small Cells Global congress, Kevin Baughan from Virgin Media gave an interesting talk on their recent trials. This is the architecture they are proposing.  

They would do site acquisition and maintenance, provide the backhaul and power, any mobile network operator (MNO) can come and put their small cell on the furniture to provide the coverage. I am not sure if multiple operators would pitch for the same sites but I wouldnt think of this as a problem as I am sure there would be multiple sites available in the same location.

A real killer from Virgin media could have been that it does something similar to Free, the French mobile operator that has apparently got Femtocells inbuilt in the set top boxes.

We will have to wait and see how many operators are willing to have third party host their small cells and how many.

Thursday, 1 November 2012

‘Small Cells’ and the City



My presentation from the Small Cells Global Congress 2012. Please note that this presentation was prepared at a very short notice so may not be completely accurate. Comments more than welcome.

Wednesday, 3 October 2012

#LTEAsia 2012 Highlights - via Alan Quayle

A summary of LTE Asia 2012, slides and highlights via Alan Quayle blog.



Some of the interesting findings from the conference include:
  • TD-LTE is gaining momentum, and its beyond WiMAX operators and China mobile, many APAC operators are considering it for unpaired spectrum and to efficiently meet the asymmetric capacity requirements of mobile broadband which is mainly download
  • Software defined radio and self-organizing networks are proving critical to manage operational costs
  • Single RAN is proving the best way to manage network performance
  • Signaling is in a mess - what is the good of standards when it creates such a mess?
  • IMS gaps continue - what is the good of standards when it doesn't meet basic migration needs?
  • The SS7 guys have reinvented themselves as the Diameter guys
  • Business model innovation - LTE is not just for mobile devices, LTE is for quad play and an interesting array of business applications
  • The 3G network of many operators is congested - forcing the move to LTE
  • CSFB (Circuit Switched Fall Back) works
  • VoLTE testing / roaming / network issues remain - given voice remains by revenue the core service, our industry should be ashamed we're having so many problems with VoLTE
  • A belief on OTT partnering, but not quantification on the OTT's willingness to pay for QoS (Quality of Service)
  • Many operators have a question mark on the use of WiFi off-load - its not a technology issue rather one of economics and customer experience, LTE-A and small cells in hotspots appears to be the focus.

Briefly reviewing the slides shown below:

  • LTE Data Points
    • 96 Commercial LTE deployments mainly in the 1.8 and 2.8GHz bands
    • APAC has 40% of LTE subscribers, likely to be the high growth region
    • Drivers for LTE: Throughput, efficiency and low latency
    • TD-LTE: 12 commercial deployments, 24 contracts and 53 Trials
    • Streaming video dominates traffic on handheld devices, with YouTube being the top traffic generator at 27% of peak traffic
  • South Korea Data Explosion
    • South Korea has seen OTT explode, Kakao Talk 51 mins of usage per day
    • 20 times smartphone growth in 2 years (28M in June 2012, 53% penetration)
    • 60 times mobile data growth to 37TB per month in 2 years, 32% is from LTE devices
    • LTE subs use 2.9GB per month compared to 3G sub on average use 1.2GB
    • LTE subs reached 10M, 141% monthly growth
    • Customer drive for LTE is speed (37%) and latest device (31%)
    • Challenge Jan 2010 and Jan 2012 ARPU fallen from $48-$35 while data use risen from 180MB to 992MB
    • Focus beyond voice, messaging and data into VAS: virtual goods (Korean thing), ICT (Information and Communication Technology) and cloud services / solutions (focus on enterprise)
  • HK CSL Migration to LTE
    • 3G is congested, LTE is not
    • Key is LTE devices available, unlike the early 3G days
    • Migrating customers away from unlimited plans to family and shared plans that deliver value
    • LTE sub uses 2-5 times the data of 3G subs
    • CSFB works
    • Average speed seen is 20 Mbps
    • Using Software Defined Radio, Single vendor RAN, Self-Organizing Networks
    • Migration to LTE-A, small cells and WiFi where appropriate
  • Starhub's migration to LTE (they launched LTE at the event)
    • 50% of voice traffic is still on 2G
    • Using AMR to re-farm 2G spectrum to LTE
    • Site access is critical - drive to software defined radio to avoid site visits
  • NTT DoCoMo's VoLTE Evolution
    • 70% devices in portfolio are now LTE
    • All smartphones support CSFB
    • Drive to VoLTE is simply to switch off 3G voice (2G already off)
    • BUT IMS has missing functionality / standards - migration from 3G to VoLTE is not easy - example of failing in standards on basic issues
  • Yes: Example of innovative converged 4G operator in an developing market that uses web principles for service delivery
  • Role of Mobile Identity in BYOD (Bring Your Own Device)
    • BYOD is as significant a trend if APAC as any other market
    • Provides a nice review of the approaches in managing BYOD
  • LTE Quad-Play in Emerging Markets: TD-LTE case study
  • Smartphone growth implications: Review of the signaling problem and mitigation strategies across 3G and LTE.  Highlights challenge current standards process 


Read the complete post here.

Tuesday, 25 September 2012

LTE, M2M Device Addressing and IMSI


I was made aware of the following statement on the Verizon wireless brochure:

LTE’s inherent support for IPV6 addressing and IMSI-based telephone number identifiers makes mass deployments over LTE more easily achievable. The deployment of large numbers of mobile devices (think tens of thousands) becomes much more feasible because of LTE’s use of 15-digit IMSI telephone number identifiers for large-scale deployments, such as M2M or embedded wireless applications. 3G network technologies were limited by their use of 10-digit telephone number identifiers, which made large-scale deployments more difficult. With LTE, mass deployment of wireless services and applications, such as VoIP, smart metering, vending, and telematics, is now practical.

Now we know about the much touted 50 Billion connections by 2025 of which the majority would be M2M devices. So how are we going to handle the issue of addressing these many devices.

In the earlier presentation here, there was a mention of the direction for the solution as below:





The IMSI structure is as shown above. So depending on how it is used this can help alleviate the number shortage problem. 3GPP TR 23.888 gives the following information:


5.13      Key Issue - MTC Identifiers

5.13.1    Use Case Description

The amount of MTC Devices is expected to become 2 orders of magnitude higher than the amount of devices for human to human communication scenarios. This has to be taken into account for IMSI, IMEI and MSISDN. Regulatory bodies indicate shortages of IMSIs and MSISDNs.
The MTC Feature PS Only in TS 22.368 [2] includes a requirement that PS Only subscriptions shall be possible without an MSISDN. In principle an MSISDN is not used in any of the PS based signalling procedures. However, it will have to be assured that all PS procedures indeed work and subscriptions can be uniquely identified without providing an MSISDN. Furthermore, TS 22.368 [2] specifies that remote MTC Device configuration shall be supported for PS only subscriptions without an MSDISDN assigned. Current remote MTC Device configuration solutions (i.e. Device Management and Over-the-Air configuration) are based on SMS, which assumes the use of MSISDNs. So a solution to support remote MTC Device configuration that does not require the use of MSISDNs is needed.
The identifiers can be categorised into:
-     Internal Identifiers: used within the 3GPP system to identify a UE using a subscription (or the subscription itself e.g. when the UE is not registered).
-     External Identifiers: used from outside the 3GPP system (e.g. at the MTCsp interface), to refer to a UE using a subscription (or the subscription itself e.g. when the UE is not registered).

5.13.2    Required Functionality

-     It shall be possible to uniquely identify the ME.
NOTE 1:   This requirement relates to the ME which is generally identified by the IMEI.
-     It shall be possible to uniquely identify the UE using a subscription or the subscription itself.
NOTE 2:   The two requirements above also apply to human-to-human communications. However, for Machine-Type Communication identifiers will have to be able to cater for a number of identifiers up to two orders of magnitude higher than for human-to-human communications.
-     It shall be possible to use the following identifiers:
1.       IMSI, for internal usage within the 3GPP operator domain, and either
2.       E.164 MSISDN, for usage outside the 3GPP operator domain, or
3.       Unique identifier (e.g. FQDN), other than E.164 MSISDN, for usage outside the 3GPP operator domain.
NOTE 3: Use of IMSI outside the 3GPP operator domain is an operator option (i.e. not subject to standardization)
-     If no (unique or common) MSISDN is assigned to a PS only subscription, the Internal Identifier (IMSI) shall be used as charging identifier.
-     It shall be possible to associate one or more External Identifiers to the same Internal Identifier (e.g. several MSISDNs associated with the same IMSI).
-     Globally unique External Identifiers shall be supported for identifying UEs used for MTC that must be globally reachable (i.e. irrespective of which mobile operator owns the subscription)
-     Operator specific External Identifiers (e.g. based on a private numbering plan) may be supported for identifying UEs used for MTC that have to be reachable only from the operator domain to which they are subscribed.
-     The Internal Identifier shall be globally unique.
-     Remote MTC Device configuration shall still be supported for subscriptions without an MSISDN.
NOTE 4:   Current remote MTC Device configuration solutions (i.e. Device Management and Over-the-Air configuration) are based on SMS, which assumes the use of MSISDNs.


Any more information on this subject, more than welcome.

Wednesday, 5 September 2012

Qualcomm's 1000x Challenge

Qualcomm has been promoting the '1000x' challenge and has recently held a webinar to make everyone aware of how 1000 times efficiency may be achieved. I think there is always a scope of achieving a better efficiency but putting a figure may not necessarily give the desired results. Anyway, here are the slides.



You can listen to the webinar here. The promotional video is available here.

A writeup on this topic by Steven Crowley is available here.

Friday, 20 July 2012

Twitter et al. for Small Cell Planning

A recent report in Light Reading mentioned about using Twitter for planning of Small Cells network. In fact for quite a while, a UK based company, Keima has been using this technique to help plan small cells deployments in the US. I used some of their research in my presentation in the Optimisation conference; see here.

A map using the Keima tool showing the activity on the Social Networks for London is as follows.



It would be very interesting to see the above during olympics.

If you are interested in learning more about the tool see Keima's presentation from MWC here and their video here.

Keima’s Simon Chapman will be presenting to the Cambridge Wireless Small Cells SIG event on 3rd October on the topic "Deploying bigger numbers of smaller cells". Here is a summary of things going to be discussed by them:




We discuss how "small cells" are a natural evolution of network design principles started with A.H. Ring in 1947. We discuss the practical consequences of managing interference while rolling out more cells in the next few years than all the previous deployments put together.


We consider processes for achieving cost-effective, spectrally efficient network capacity and establish the most influential: the location of small cells. Given the importance of location we demonstrate mechanisms for identifying demand hotspots using publicly available datasets and show that this knowledge alone has a significant impact on the eventual network capacity.


Finally, as we look at the immediate areas in and around demand hotspots, we discuss the associated issues of selecting thousands of utility poles or building-side mountings; of managing wired or wireless backhauling; of lowering latency; of repurposing the macro


To register for the event please click here.

Wednesday, 18 July 2012

Real Life Pictures of Small Cells Deployments in London

Visitors of this blog seemed to like the last set of deployment pictures I put up. As a result here is another set of pictures from the same Telefonica presentation by Robert Joyce. See also my earlier post on the same topic here.













Friday, 15 June 2012

Three Phases of WiFi Integration


From a presentation by Ericsson in the LTE World Summit 2012. Presentation available here.

Operator WiFi is becoming an important proposition and there are advantages and disadvantages of both of them. The above picture summarises the phases in which it may take place.

See also:

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.

Monday, 9 April 2012

Radio relay technologies in LTE-Advanced

The following is from NTT Docomo Technical journal

Three types of radio relay technologies and their respective advantages and disadvantages are shown in Figure 1. 
A layer 1 relay consists of relay technology called a booster or repeater. This is an Amplifier and Forward (AF) type of relay  technology by which Radio Frequency (RF) signals received on the downlink from the base station are amplified and transmitted to the mobile station. In a similar manner, RF signals received on the uplink from the mobile station are amplified and transmitted to the base station. The equipment functions of a layer 1 relay are relatively simple, which makes for low-cost implementation and short processing delays associated with relaying. With these  features, the layer 1 relay has already found widespread use in 2G and 3G mobile communication systems. It is being deployed with the aim of improving coverage in mountainous regions, sparsely populated areas and urban areas as well as in indoor environments.


The RF performance specifications for repeaters have already been specified in LTE, and deployment of these repeaters for the same purpose is expected. The layer 1 relay, however, amplifies intercell interference and noise together with desired signal components thereby deteriorating the received Signal to Interference plus Noise power Ratio (SINR) and reducing the throughput enhancement gain.


The layer 2 relay, meanwhile, is a Decode and Forward (DF) type of relay technology by which RF signals received on the downlink from the base station are demodulated and decoded and then encoded and modulated again before being sent on to the mobile station. This demodulation and decoding processing performed at the radio relay station overcomes the drawback in layer 1 relays of deteriorated received SINR caused by amplification of intercell interference and noise. A better throughput-enhancement effect can therefore be expected compared with the layer 1 relay. At the same time, the layer 2 relay causes a delay associated with modulation/demodulation and encoding/decoding processing. In this type of relay, moreover, radio functions other than modulation/demodulation and encoding/decoding (such as mobility control, retransmission control by Automatic Repeat request (ARQ), and user-data concatenation/segmentation/reassembly) are performed between the base station and mobile station transparently with respect to the radio relay, which means that new radio-control functions for supporting this relay technology are needed. 




The layer 3 relay also performs demodulation and decoding of RF signals received on the downlink from the base station, but then goes on to perform processing (such as ciphering and user-data concatenation/segmentation/reassembly) for retransmitting user data on a radio interface and finally performs encoding/modulation and transmission to the mobile station. Similar to the layer 2 relay, the layer 3 relay can improve throughput by eliminating inter-cell interference and noise, and additionally, by incorporating the same functions as a base station, it can have small impact on the standard specifications for radio relay technology and on implementation. Its drawback, however, is the delay caused by user-data processing in addition to the delay caused by modulation/demodulation and encoding/decoding processing.


In 3GPP, it has been agreed to standardize specifications for layer 3 relay technology in LTE Rel. 10 because of the above features of improved received SINR due to noise elimination, ease of coordinating standard specifications, and ease of implementing the technology. Standardization of this technology is now moving forward.


Layer 3 radio relay technology is shown in Figure 2. In addition to performing user-data regeneration processing and modulation/demodulation and encoding/ decoding processing as described above, the layer 3 relay station also features a unique Physical Cell ID (PCI) on the physical layer different than that of the base station. In this way, a mobile station can recognize that a cell provided by a relay station differs from a cell provided by a base station.


In addition, as physical layer control signals such as Channel Quality Indicator (CQI) and Hybrid ARQ (HARQ) can terminate at a relay station, a relay station is recognized as a base station from the viewpoint of a mobile station. It is therefore possible for a mobile station having only LTE functions (for example, a mobile station conforming to LTE Rel. 8 specifications) to connect to a relay station. Here, the wireless backhaul link (Un) between the base station and relay station and the radio access link (Uu) between the relay station and mobile station may operate on different frequencies or on the same frequency. In the latter case, if transmit and receive processing are performed simultaneously at the relay station, transmit signals will cause interference with the relay station’s receiver by coupling as long as sufficient isolation is not provided between the transmit and receive circuits. Thus, when operating on the same frequency, the wireless backhaul-link and radio-access-link radio resources should be subjected to Time Division Multiplexing (TDM) so that transmission and reception in the relay station are not performed simultaneously.




Scenarios in which the introduction of relay technology is potentially useful have been discussed in 3GPP. Deployment scenarios are shown in Table 1. Extending the coverage area to mountainous and sparsely populated regions (rural area and wireless backhaul scenarios) is an important scenario to operators. It is expected that relay technology can be used to economically extend coverage to such areas as opposed to deploying fixed-line backhaul links. Relay technology should also be effective for providing temporary coverage when earthquakes or other disasters strike or when major events are being held (emergency or temporary coverage scenario), i.e., for situations in which the deployment of dedicated fixed-line backhaul links is difficult. In addition, while pico base stations and femtocells can be used for urban hot spot, dead spot, and indoor hot spot scenarios, the installation of utility poles, laying of cables inside buildings, etc. can be difficult in some countries and regions, which means that the application of relay technology can also be effective for urban scenarios. Finally, the group mobility scenario in which relay stations are installed on vehicles like trains and buses to reduce the volume of control signals from moving mobile stations is also being proposed.


In 3GPP, it has been agreed to standardize the relay technology deployed for coverage extension in LTE Rel. 10. These specifications will, in particular, support one-hop relay technology in which the position of the relay station is fixed and the radio access link between the base station and mobile station is relayed by one relay station.



References
[1] 3GPP TS36.912 V9.1.0: “Feasibility study for Further Advancement for E-UTRA (LTE-Advanced),” 2010.
[2] 3GPP TS36.323 V9.0.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification,” 2009
[3] 3GPP TS36.322 V9.1.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control (RLC) protocol specification,” 2010.
[4] 3GPP TS36.321 V9.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification,” 2010.
[5] 3GPP TS36.331 V9.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification,” 2010.
[6] 3GPP TS36.413 V9.2.1: “Evolved Universal Terrestrial Radio Access (E-UTRA); S1 Application Protocol (S1AP),” 2010.
[7] 3GPP TR36.806 V9.0.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Relay architectures for E-UTRA (LTEAdvanced),” 2010.
[8] IETF RFC4960: “Stream Control Transmission Protocol,” 2007.
[9] 3GPP TS29.281 V9.2.0: “General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U),” 2010.


Monday, 12 September 2011

LTE Rollouts and Deployment Scenarios

According to GSA report, as of August 2011, 26 commercial LTE networks in 18 countries are already rolled out as below:
As of Aug. 2011, 237 operators in 85 countries are investing in LTE:

* 174 LTE network commitments in 64 countries
* 63 pre-commitment trials in 21 more countries
* 26 commercial LTE networks launched
* At least 93 LTE networks are expected to be in commercial service by end 2012

The following is from the 4G Americas whitepaper:

There are many different scenarios that operators will use to migrate from their current networks to future technologies such as LTE. Figure 10 presents various scenarios including operators who today are using CDMA2000, UMTS, GSM and WiMAX. For example, as shown in the first bar, a CMDA2000 operator in scenario A could defer LTE deployment to the longer term. In scenario B, in the medium term, the operator could deploy a combination of 1xRTT, EV-DO Rev A/B and LTE and, in the long term, could migrate EV-DO data traffic to LTE. In scenario C, a CDMA2000 operator with just 1xRTT could introduce LTE as a broadband service and, in the long term, could migrate 1xRTT users to LTE including voice service.


3GPP and 3GPP2 both have specified detailed migration options for current 3G systems (UMTS-HSPA and EV-DO) to LTE. Due to economies of scale for infrastructure and devices, 3GPP operators are likely to have a competitive cost advantage over Third Generation Partnership Project 2 (3GPP2) operators. One option for GSM operators that have not yet committed to UMTS, and do not have an immediate pressing need to do so, is to migrate directly from GSM/EDGE or Evolved EDGE to LTE with networks and devices supporting dual-mode GSM-EDGE/LTE operation.

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.