After more than 20 years, it appears that an almost universally-accepted standard for mobile radio may finally be implemented, bringing to an end the standards war between carriers that deployed TDMA/GSM for second generation and carriers that deployed CDMA for second generation. Those two factions continued the standards war for the third generation (UMTS and 1X respectively); but now carriers from both of the factions are supporting the GSM/UMTS faction’s Third Generation Partnership Project (3GPP) release 8, known as Universal Terrestrial Radio Access Network Long Term Evolution (LTE).

LTE appears to have triumphed over alternatives 802.16 WiMax and Qualcomm’s Ultra Mobile Broadband. LTE promises co-existence with other standards, allowing in theory handoffs between cells supporting LTE and cells supporting UMTS, GSM/GPRS, 2G CDMA, CDMA-MC or 1XEV-DO.

LTE’s spectrum-sharing method, called Orthogonal Frequency Division Multiplexing (OFDM), is different than that of previous generations, providing flexible and efficient use of different carrier bandwidths along with tolerance to noise and multipath interference. Bit rates are on the order of 100 Mb/s when a 20 MHz carrier is employed. As with all claims for wireless bit rates, these are peak burst rates under ideal conditions with one user per cell.

Multiple-Input, Multiple-Output (MIMO) antenna designs can increase the bitrate using spatial multiplexing, which is basically gluing several antennas together. Interestingly, OFDM is also used for 802.11 Wi-Fi and DSL.

OFDM is not like 3G CDMA. On the downlink, many 15-kHz subcarriers are defined within the radio band. The bit stream is used to modulate the subcarriers individually; in the most complex implementation, each of hundreds of subcarriers is used to transmit 6 bits at a time with QAM-64. These are all added together to produce a transmittable waveform… and this is calculated in one step with highly-complex digital signal processing called an Inverse Discrete Fourier Transform. The figure below illustrates an example using the very simplest type of modulation of the subcarriers, binary Amplitude Shift Keying, i.e. tones that are either on or off to represent 1 and 0.

LTE: Orthogonal Frequency-Divison Multiplexing (OFDM) - transmitter

At the receiver, a Fourier transform performs the reverse process to yield the original bit stream. This happens at the same rate as the subcarrier spacing, 15,000 times per second, which has the result of making the harmonics of all of the other subcarriers cancel out during the detection of a given subcarrier at the receiver, hence the term orthogonal.

Prior to modulation, Forward Error Correction is implemented, adding redundancy to the bit stream so that correct decisions can be made based on maximum likelihood in the presence of impairments like noise and fading. The bit stream is also shuffled or interleaved, re-arranging the order of the bits in time so that burst errors are no longer sequential errors.

On the uplink, LTE uses a pre-coded version of OFDM called Single Carrier Frequency Division Multiple Access (SC-FDMA) to avoid the need for expensive and inefficient power amplifiers, which would increase handset cost and shorten battery life.

One of the reasons for the 3G standards war was the requirement to pay American company Qualcomm royalties on patents for several techniques necessary for a mobile CDMA system. LTE is not CDMA, so those royalties are avoided… but it turns out that Qualcomm filed or has purchased many patents that underpin LTE. Additionally, since LTE phones will have to be backwards-compatible with 3G CDMA networks, Qualcomm sees “no impact” on patent royalty revenue for the first ten years of LTE development according to COO Sanjay Jha.

The 3GPP Technical Report 25.913 contains the detailed requirements specification for LTE. The system architecture, in Technical Specifications 36.300 and 36.401, is simplified to two principal network elements: evolved Network Base stations (eNBs) and Evolved Packet Cores (EPCs). eNBs communicate with EPCs, with each other and with user equipment.

LTE is slated to become part of IMT-2000, the 3G “standard”, so in a strict standards committee environment, LTE would be called a 3G technology. An updated version, 3GPP release 10, which might be called LTE-Advanced, is expected to be submitted to the IMT-Advanced standards committee, which would cause those standards committee members to declare it officially a 4G standard. Everyone else will refer to LTE as 4G from the start.

From Course 101: Telecom, Datacom and Networking for Non-Engineers, rev 2008-10 page 6.19
and from the upcoming new DVD 7 “Understanding Wireless 2″ scheduled for release in 2009.

A switch, in its simplest form, is a device that causes communications to happen from one point to one other particular point, often when there are multiple “other” points to choose from.

A traditional Central Office (CO) telephone switch might be called a “hard” switch, since it has physical line cards that terminate loops. The switching software running on the computer which is the CO switch directs traffic between a line card and a trunk or between two line cards during a phone call.

The term soft switch is used to mean a computer running switching software that does not have telephone line cards – the communications are instead directed to the correct destination by routers routing packets, a software function.

As there are different approaches for the architecture – centralized vs. distributed switching, for example – and many, many vendors of products, there are many implementation variations and a plethora of jargon and buzzwords in this area. Soft switches are deployed by carriers to provide network-based services, and by end-user business customers to do it themselves.

Different standards for call setup define terms: the dominant Session Initiation Protocol (SIP) uses the terms proxy and back-to-back user agent; the older H.323 defines a gatekeeper. Terms used by product manufacturers for their products that might implement these and other functions include call manager, call server, VoIP switch, communication server and hosted PBX.

Regardless of what it is called, there are in general two main functions that may be performed by a soft switch: terminal control and call control.
Terminal control includes registration, admission and status. Registration means authenticating a telephone (or telephone client software) and associating the telephone and its IP address with a user in a directory. Admission means controlling whether that telephone is permitted to make or receive calls. Status is keeping track of the current status of the telephone, client software and/or user as an input to processing call requests.

Call control can involve a number of different functions, including address resolution, call routing, call signaling and call accounting. Address resolution means determining the numeric IP address of the called telephone. Call routing in an IP telephone network boils down to determining the IP address of the next hop for the phone call – usually a router – based on the destination address and the available networks and services. Call signaling includes initiating and terminating the phone call by exchanging control messages with a far-end device. This often includes negotiation of the multimedia attributes and coding protocol for the communications. The soft switch may also use the signaling and other information to generate Call Detail Records as an input to a call accounting system.

In addition to these basic functions, specific products may include hundreds of other functions such as those needed for call centers.

Source: Teracom’s Course 130: Understanding Voice over IP, pages 1.03 and 1.04

Paying the Incumbent Local Exchange Carrier (ILEC) for tariffed services, either switched access or dedicated lines, to connect the last mile from a competitive carrier’s Point of Presence (POP) to the competitive carrier’s customer started to become widespread in 1984.

Subsequent legislation and regulatory decisions unbundled the ILEC’s physical access network from the ILEC’s services provided on that network. This enabled competitive carriers to lease just the ILEC’s physical cabling to the customer instead of paying for a tariffed service. If the ILEC is providing copper wires without electricity on them, i.e. not attached to a CO switch line card, this is called a dry circuit. A fiber not attached to a line card is called dark fiber.

In addition to being required to lease dry copper or dark fiber to their competitor, the ILEC is required to build colocation facilities in its COs. These are rooms, often with separate entrance doors, where the competitive carrier can locate their own circuit-terminating equipment like modems and line cards, and network equipment like switches, multiplexers and routers.

When a company collocates equipment in the CO and connects it to the ILEC’s cabling, the competitive carrier is said to be acting as a Competitive Local Exchange Carrier (CLEC).

Going even further, the competitive carrier can simply lay their own fiber from their POP to their large customers and bypass the ILEC altogether.  

To ensure high availability in any kind of network, more than one physical connection is required to every station, on different cables, to protect against cut lines. It turns out that the cheapest way to do this is to connect them neighbor-to-neighbor-to-neighbor to form a ring.

The competitive carrier’s POPs in cities are connected to form regional rings, which are interconnected at multiple places to implement national communications.

Within a metropolitan area, a competitive carrier will install or lease fiber to connect their POP to the ILEC’s toll center, to the ILEC’s COs where they have collocations, and to their large customers. These physical locations are also connected neighbor-to-neighbor to form a ring for redundancy; the ring is the MAN.   From Course 101: Telecom, Datacom and Networking for Non-Engineers, rev 2008-10 pages 3.14 and 3.15 ]]> http://blog.teracomtraining.com/tutorial-the-mature-competitive-environment-regional-rings-and-mans/feed http://blog.teracomtraining.com/course-101-certification-exam-auto-scoring-free-sample http://blog.teracomtraining.com/course-101-certification-exam-auto-scoring-free-sample#comments Fri, 07 Nov 2008 22:11:05 +0000 Eric Coll http://blog.teracomtraining.com/?p=17 We’ve posted a new free online resource: a portion of the
Course 101 online certification exam.  
To access this or any of our vast selection of free samples,
you may be asked to sign in or sign up for myTeracom. 
It’s free, easy, secure and confidential.

It gives your score automatically! 
This sample certification exam is part of Teracom’s quality all-inclusive training
- along with the course pages previews and/or DVD-video and CBT previews, 
   it is a good way to assess the level and quality of Teracom Training
- plus, assess your current knowledge level to help you decide you do need training!

Check it out!

Check out the new sessions scheduled so far:
 Course 101: Telecom, Datacom and Networking for Non-Engineers
 Course 130: Understanding Voice over IP
 BOOT CAMP: Course 101+130 together - save 30%
 Course 110: Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers

Don’t miss Course 101 and 130 together in TRINIDAD being held in conjunction with
CANTO, the Carribean Association of National Telecommunications Organizations 

It ain’t. The Internet is a business.

And network service is not and has never been all-you-can-eat-at-access-line-speed flat-rate service. It can’t be, as networks are designed based on statistical multiplexing. The capacity internal to the network is less than the total of the access line speeds. If the network was designed for everyone doing all-you-can-eat-at-access-line-speed, the internal capacity would have to be increased by an order of magnitude. Network service would cost 10 times a much.

Network service is a Service Level Agreement, a contract between the user (traffic profile) and the network (transmission characteristics). Watch the video tutorial I prepared explaining the idea of a Service Level Agreement on YouTube.

Now, if you want to set up an IP network and operate it as a utility, you are certainly free to do so. But you will very quickly find out that you have to *pay* to connect your IP network to other IP networks so that your subscribers can transmit and receive packets to machines not on your network.

Then you will find out that there are two basic kinds of interconnect services for sale on the free market: peering and transit. Peering is the cheaper option, and doesn’t usually include termination guarantees, the network you give your packets to will likely pass them on to one of their peers to get rid of them as quickly as possible. Transit is more expensive, as it usually includes termination and delivery guarantees.

Then you will find out that no-one offers unlimited plans. Only Service Level Agreements based on the RFC2475 Differentiated Services (http://www.faqs.org/rfcs/rfc2475.html) and implemented using MPLS, with transmission characteristics like RFC3246 Expedited Forwarding and RFC2597 Assured Forwarding are for sale.

So you, as the Utility IP network, do some research to determine, based on statistics, what service levels you need to buy for interconnect. You pay for those, then try to break even (if you are a not-for-profit utility) or make some money (if you are a business) charging retail for subscriber access, and providing transit and peering services to other IP networks.

And being altruistic, you make your Utility IP network service unlimited and application-agnostic.

Then 1% of your users run bittorrent 24/7, and it turns out that they use as much interconnect bandwidth as the other 99% of your customers.

So you have to double the interconnect bandwidth, doubling your cost. But you can’t raise prices much. You are now in a money-losing situation.

Now, more and more bittorrenters sign up for your service since it is unlimited and application-agnostic. What do you do?
- Go out of business (many ISPs did that)
- Put usage caps on new subscriptions. (Nasty bad press for doing that, but your solution)

OK, now what about all the existing subscribers who have grandfathered unlimited plans? And all of the existing peering and transit contracts you signed on the sell side that have unlimited plans? Including universities?

You analyze the network traffic, and discover that the problem is 1% of your users are generating 50% of the traffic, using one or two applications. And these applications are being used for stealing copyrighted works without paying the authors. Your legal department warns you that on top of the network congestion, there is a risk that the copyright holders will sue you, the network provider, for allowing people to steal their stuff.

What do you do?

- Lose money until you go out of business

- Can’t put usage caps on grandfathered subscriptions.

- Ignore the legal risk

- Implement traffic engineering techniques in the network to police the 1% of users so that their overage is only transmitted when there is spare capacity, to ensure that
a) the 99% of users get what they are paying for and
b) you don’t have to increase your network infrastructure and its costs by an order of magnitude to scale the network to meet the demand of the 1%ers.

- or maybe plead with the bittorrenters to be good network citizens and kindly stop running that application, as your network was not designed to handle the traffic it generates

- other suggestions?

ALL “NET NEUTRALITY” ARTICLES:

Net Neutrality - Foolish, ignorant or disingenuous?

Net Neutrality II: If the power company allowed this, your electrical bill would double

Net neutrality - not. VideoTutorial on Service Level Agreements, traffic shaping and traffic policing

Is the Internet a Public Utility?

watch in higher quality on youtube’s site

When someone demands “net neutrality”, they usually mean that the network must not discriminate between applications being carried in IP packets; that identical transmission characteristics (throughput, delay, number of errors, etc.) are to be provided for all packets regardless of what is being carried in them. They claim (correctly) that this is not the case at present, that the network service provider is “throttling” certain applications, “slowing down” or “shaping” traffic (the correct term is “policing”) and that this, in their opinion, must stop.

This video tutorial explains Service Level Agreements, traffic profiles, transmission characteristics, and how Differentiated Services (Diff-Serv) is implemented to be able to provide different transmission characteristics for different kinds of traffic - the EXACT OPPOSITE of net neutrality.

It is taken from Teracom’s DVD video V9 Understanding Voice over IP 2: Voice Packetization • Voice Quality • Codecs, Jitter and Packet Loss • Diff-Serv • Network QoS with MPLS

ALL “NET NEUTRALITY” ARTICLES:

Net Neutrality - Foolish, ignorant or disingenuous?

Net Neutrality II: If the power company allowed this, your electrical bill would double

Net neutrality - not. VideoTutorial on Service Level Agreements, traffic shaping and traffic policing

Is the Internet a Public Utility?

Visit Teracom Training Institute for more information on telecommunications training and voip training

But a demand for “net neutrality” is usually also wrapped together with a demand by these same people for no metering, no usage charges. This would mean that users who are continuously transmitting and receiving packets would pay the same flat rate as someone who is paying only for a typical traffic profile.

If this principle were applied to electricity, it would be like having no electricity meter. Everyone pays the same, regardless how much power they use. The problem: if you’re one of the 99% of normal users, you would have to pay DOUBLE what you normally would, to cover the costs of the 1% of users constantly drawing 200 amps 24 hours a day, 7 days a week, 365 days a year.

Here’s how that would work:

You, along with the other 99% of people in your city use maybe 50 amps, at various times during the day, most of the time a lot less… a usage profile that fits within a pretty narrow bell curve. Knowing this usage profile, how much money it costs to fire up those oil-fired generators to produce that much electricity, and the costs to develop capital infrastructure to deliver it, we can calculate what the monthly flat rate should be.

But hold on, it turns out that we haven’t taken into account the net-neutrality advocates, who are the 1% of the people in your city who would take advantage of this to draw the max: 200 amps 24 hours a day, 7 days a week, 365 days a year.

To pay for them, the flat rate has to be raised. Everyone has to pay more.

OK, you’re thinking, raised a little more, what’s the big deal? So everyone pays, what, $53 per month instead of $50 to cover the 1% of full-bore users who are drawing 200 amps 24/7/365 ?

Here’s the problem: it ain’t just a bit extra. The power used by the 1% is equal to what you and the other 99% use together. The 1% double the demand. So the price increase to pay for this 1% of users is closer to $50 in the example above. Instead of paying $50, which is your fare share, we would be talking about everyone else paying more like $100 to cover those 1% of people who use a LOT more power than you do.

Sound like a good deal?

Yes, if you are one of the 1%, (the net-neutrality advocates!)
… but not if you are one of the 99% and use pretty much the same amount of power as your neighbors.

And the net-neutrality advocates make this sound like it is a noble objective?
They have the moral high ground?

Carriers are “bad” and “corporate” because they give these 1% a choice:
- pay the same and use the same, or
- pay more and use more,
instead of making the 99% subsidize them?

Give me a break.

And don’t forget what they are doing is basically stealing… the disingenuous part.

ALL “NET NEUTRALITY” ARTICLES:

Net Neutrality - Foolish, ignorant or disingenuous?

Net Neutrality II: If the power company allowed this, your electrical bill would double

Net neutrality - not. VideoTutorial on Service Level Agreements, traffic shaping and traffic policing

Is the Internet a Public Utility?

“NET NEUTRALITY” AND IP NETWORKING TECHNICAL RESOURCES:

TERACOM VIDEOTUTORIAL V9: QoS and Traffic Conditioning:
http://www.teracomtraining.net/previews/TERACOM-VIDEOTUTORIAL_V9-qos-and-traffic-conditioning.wmv
http://www.youtube.com/watch?v=dSNhcJDuA2s

Course 101 Telecom, Datacom and Networking for Non-Engineers,
  Chapter 3-3 “Bandwidth-On-Demand: Packet Network Services” and following

Course 110 Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers,
  Chapter 14. Quality of Service in the IP World: NET NON-NEUTRALITY

Video Course DVD-4 “Understanding Networking 1″
  Part 3 WANs - Bandwidth On Demand: Packet Network Services

Telecom 101 Textbook
 Chapter 18 Bandwidth on Demand

 
Foolish: The Internet Protocol, IP, does not provide any guarantees. There is no guarantee that a packet will be transmitted, when that might happen, how often that might happen, or how long it will take to reach its destination. Nothing. Nada. Zip. Bupkes. In IP, there is even no way for a device to which a packet is proposed to be transmitted to report back whether it got the packet, sent it onward or what. Nothing. This is called a connectionless, unreliable network service. 
 
Here’s the foolish part: if we are to use an IP network for real-time, delay- and loss-sensitive applications like phone calls and watching television, implementing Quality of Service (QoS) mechanisms to guarantee transmission characteristics is essential… otherwise, there is no way to guarantee quality of the reconstructed signal at the destination. Television pictures would freeze, then jump forward, sometimes have block distortion effects and other artifacts. Clicks, pops, muting, breaking up and similar effects would be heard on phone calls. Saying that we should not take measures to prevent this is foolish. All phone calls and television will happen over IP in the future. 
 
Guaranteeing transmission characteristics is easy if there is no traffic on the network. The difficulty happens when there is contention, either for the use of an outgoing circuit at a network device, or contention for the use of the processor in a network device… and this contention is going to have to be resolved in favor of real-time, delay- and loss-sensitive applications like phone calls and watching television to the detriment of applications that are less sensitive to delay and packet loss like web page downloads, email and file transfers. 
 
Here’s the ignorant part: IP network service providers are not operating IP networks as such. They are operating MPLS networks. MPLS is the IP world’s implementation of virtual circuits, where we define classes of traffic and pre-determine routes and relative priorities for the classes. A class of traffic is a flow of packets going from the same place to the same place and should experience the same transmission characteristics. We establish multiple classes going from the same place, to the same place but each with a different specified transmission characteristic. This way, the class is a number to look up in a table in an intermediate routing node that will yield the address of the next-hop device and the priority level of the packet. 
 
At the entrance to the MPLS network, the first MPLS router, called the ingress device, analyzes the packet to determine what (among other things) application is being carried in the packet (voice, video, music, email, web page, etc.) to determine class it belongs to, and when it decides, pastes a label on the front of the IP packet with a number indicating the class. Intermediate Label Switching Routers in the network do not examine the IP address, they use the number in the label to lookup the routing decision and the priority level of the packet. This is how Quality of Service is implemented on packet networks.

It’s ignorant for these supposedly-well-informed net-neutrality advocates to talk about “IP” networks when they are actually MPLS networks, and one of the main reasons for the network operator having implemented MPLS was to be able to prioritize packets based on the application being carried inside them, to be able to guarantee transmission characteristics for phone calls and watching television!  MPLS as the Quality of Service (QoS) technology to implement the exact opposite of “net neutrality” is already in place on all commercial IP networks.  It was used to manage the bandwidth for the download of the article you are reading right now!  Too late.

More ignorance: thinking that the Internet is a public utility.  It ain’t.  It’s a business.  read more here
 
“Disingenuous” is usually defined as being not straightforward or candid; giving a false appearance of frankness; being insincere. Here’s the disingenuous part: the application that is being “throttled” or traffic that is being “shaped” or “slowed” (the correct term is “policed”) is piracy. Theft. In most places, illegal activity. Downloading illegal copies of copyrighted material. Stealing. 
 
The category of application being policed is peer-to-peer file sharing. Examples of this kind of application include bittorrent and limewire. These applications are used 99.999% of the time to download illegally-made copies of Hollywood movies, music of all kinds from Beethoven to Eminem, training videos, software, ebooks, audio books and other copyrighted works without paying the author or publisher. Take a look at one of the bittorrent sites like piratebay dot org and click “browse torrents” to see for yourself. Yes, the advocates can describe how bittorrent was designed for the legitimate delivery of software, and trot out one example of a legitimate use… but this is definitely a case where the exception proves the rule. 99.999% of the use is theft. 
 
In English common law there is a maxim: you can’t come to court with dirty hands; in other words, you can’t ask for justice if you yourself are obviously breaking the rules. The people whose traffic is being policed have filthy dirty hands. Methinks the lady doth protest too much. 

ALL “NET NEUTRALITY” ARTICLES:

Net Neutrality - Foolish, ignorant or disingenuous?

Net Neutrality II: If the power company allowed this, your electrical bill would double

Net neutrality - not. VideoTutorial on Service Level Agreements, traffic shaping and traffic policing

Is the Internet a Public Utility?
 
 
“NET NEUTRALITY” AND IP NETWORKING TECHNICAL RESOURCES:

the most comprehensive discussion of this topic is in this course:
Course 110 Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers,
  Chapter 14. Quality of Service in the IP World:  NET NON -NEUTRALITY

Course 101 Telecom, Datacom and Networking for Non-Engineers,
  Chapter 3-3 “Bandwidth-On-Demand: Packet Network Services” and following

Video Course DVD-4 “Understanding Networking 1″
Part 3 WANs - Bandwidth On Demand: Packet Network Services

Telecom 101 Textbook
 Chapter 18 Bandwidth on Demand