Core Networking

Core Networking

Modulation Techniques for Wireless

Introduction
The purpose of analog modulation is to impress an
information-bearing analog waveform onto a carrier for
transmission.
The purpose of digital modulation is to convert an
information-bearing discrete-time symbol sequence into a
continuous-time waveform (perhaps impressed on a carrier).
Key concerns | bandwidth efficiency and implementation
complexity.

These are aected by:
  • base band pulse shape
  • phase transition characteristics
  • envelope
uctuations (channel non-linearity?)
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FREE Wi-Fi

Find and Use FREE Wi-Fi INTERNET

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How To Setup Wireless Connection (APPLY SAFETY SETTINGS FIRST)

"Don't ever connect a wireless router without doing the above safety settings. By default they are setup "loose" so that they get the fewest tech support calls. A central location of where you are most likely to use your wireless devices is desirable."

Ø Make sure your internet connection is working directly from your internet connection modem prior to connecting your router.

Ø Hook your router up as per instructions. Any wired computers will plug into the LAN connections and one cable will go to the modem.

Ø Log into the router using a wired computer with the ip address that is provided in the manual. Most are 192.168.0.1. Inputting this address in your browser's address window should get you there. Default login is "admin" , passwords vary, so check your book.

Ø Turn on WPA-PSK encryption so that the data from your computer is encrypted and not visible by your neighbor.

Ø Change the default router access password so that only you can logon.

Ø Turn off SSID broadcasting as this tells anyone passing by with a wireless device that you have a connection available; also name SSID what you want. You will use this name when connecting from your wireless device.

Ø Mac address filtering allows only your computer(s) to connect to your network so enable this as well. Finding your Mac address of your network device(s) is done by starting a command prompt window and typing "ipconfig/all" without the quotes. A typical Mac address is 00-06-5B-04-B4.

Ø Click enable Mac address filtering, then type your computer's Mac addresses in and save.

Ø WAN connection type will most likely be set to DHCP and should work fine at this setting for most applications.

Ø Fire up your computer with the wireless device installed....You did type the Mac address for this device, right?

Ø Start wireless setup wizard in Windows XP and it will walk you through connecting to your router. Use manual settings and check the box for wpa at the bottom. Remember that WPA-PSK key/password you made earlier? You will input it here. SSID name will also be entered here.

Ø If you have more than 1 computer and you would like to enable share files, click start>my network places then if you are using a Windows XP, on the side toolbar click "set up a home or small office network" and follow the steps with every computer.

Ø If all went smoothly you will now be able to safely connect wirelessly.
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GPRS Core Network

The GPRS Core Network is the centralised part of the GPRS system and also provides support for WCDMA based 3G networks. The GPRS core network is an integrated part of the GSM core network.                            

The GPRS Core Network (GPRS stands for General Packet Radio Services) provides mobility management, session management and transport for Internet Protocol packet services in GSM and WCDMA networks. The core network also provides support for other additional functions such as billing and lawful interception.

  • GPRS Tunnelling Protocol (GTP)

GPRS Tunnelling Protocol is the defining IP protocol of the GPRS core network. It is the protocol which allows end users of a GSM or WCDMA network to move from place to place while continuing to connect to the internet as if from one location at the Gateway GPRS Support Node (GGSN). It does this by carrying the subscriber's data from the subscriber's current Serving GPRS Support Node (SGSN) to the GGSN which is handling the subscriber's session. The forms of GTP used by the GPRS core network 
GTP-U: for transfer of user data
in separated tunnels for each PDP context
GTP-C: for control reasons

  • GPRS Support Nodes (GSN)  

A GSN is a network node which supports the use of GPRS in the GSM core network. All GSNs should have a Gn interface and support the GPRS Tunnelling Protocol.

There are two key variants of the GSN;

 GGSN and the SGSN 

  • Access Point

An access point is:
An IP network to which a mobile can be connected
A set of settings which are used for that connection
A particular option in a set of settings in a mobile phone

When a GPRS mobile phone sets up a PDP context, the access point is selected.

  • PDP Context

The PDP (Packet Data Protocol, e.g. IP, X.25, FrameRelay) context is a data structure present on both the SGSN and the GGSN which contains the subscriber's session information when the subscriber has an active session. When a mobile wants to use GPRS, it must first attach and then activate a PDP context. This allocates a PDP context data structure in the SGSN that the subscriber is currently visiting and the GGSN serving the subscribers access point. The data recorded includes:
Subscriber's IP address
Subscriber's IMSI
Subscriber's 
Tunnel Endpoint ID (TEID) at the GGSN
Tunnel Endpoint ID (TEID) at the SGSN

The Tunnel Endpoint ID (TEID) is a number allocated by the GSN which identifies the tunnelled data related to a particular PDP context.

There are two kinds of PDP contexts:

Primary PDP Context :  Has a unique IP address associated with it
Secondary PDP Context :  Shares an IP address with another PDP context

A total of 11 PDP contexts (with any combination of Primary and Secondary) can co-exist.

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Solutions provided by Core Networking

In the above diagram, Ethernet Protected Switched Rings (EPSR) and 10 GbE modules allow the SwitchBlade x908 advanced modular switch, with a number of x900 switches or iMAPs, to form a high speed protected ring with sub 50ms failover. This feature is perfect for high performance at the core of your Service Provider network. Comprehensive, low latency Quality of Service (QoS) features operating at wire-speed provide flow-based traffic management with full classification, prioritization, traffic shaping, and min/max bandwidth profiles. These QoS features are ideal when you want to ensure maximum availability of voice, video and data services, and simultaneously manage customer service level agreements.

Providing maximum Gigabit Ethernet port density in a 3RU chassis, the SwitchBlade x908 has a large multicast group capacity, which allows you to offer the maximum number of video services to your customers - increasing your per-port revenue. A high degree of flexibility future-proofs your investment against changes in network infrastructure, topology, and physical link requirements. Future XEM modules will provide greater Ethernet connectivity options, allowing your network to adapt in response to business needs.

Fully operational with one PSU, the second PSU provides redundancy and the ability to support dual feed where needed. These internal PSUs eliminate the need for an external Redundant Power Supply (RPS), affording you more valuable rack space. This built-in redundancy guarantees the continued delivery of essential services.


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ActiveVideo system


ActiveVideo is an immersive, media-rich viewing experience that blends the choice, control and advertising models of the Internet with the convenience, image quality and instantaneous response of cable television. 

The primary goal of ActiveVideo is to create a broadband video experience for television viewers while integrating as seamlessly as possible into the workflows used by programmers and the distribution technologies used by cable-TV networks. To achieve this, ActiveVideo uses MPEG Stitching technology to assemble cached Web content and streaming, broadcast or on-demand programming into a video stream customized for each viewer. MPEG Stitching dynamically composites a full-screen image from multiple MPEG encoded elements in response to remote control key presses as the viewer interacts with programming. ActiveVideo essentially shifts client centric application development to a flexible client-server model similar to Web browsers. 

ActiveVideo's network-based approach overcomes legacy set-top box limitations to efficiently deliver new classes of personalized multimedia applications to an operator's entire subscriber base without requiring new network or CPE capital investment. This "develop once, deploy everywhere" strategy also allows programmers and advertisers to reach mass audiences quickly and economically, reusing much of what they already produce for the Web.

ActiveVideo uses standard interfaces so Web designers can work with existing media assets and familiar Web authoring tools to create interactive programming for television. No new tools or technologies must be mastered, and ActiveVideo programming can interact with decision support and fulfillment systems using deployed Internet protocols. 

Programmers can update their designs or add functionality any time, within the terms of their business agreements with network operators. The ActiveVideo Distribution Network ensures that updates arrive promptly at the required networks, allowing programmers nearly instantaneous control of their content. This enables television programming innovation and change to move at the speed of the Internet.

How is ActiveVideo different from "traditional" interactive television?

Cable television operators currently have the most robust and high-quality networks for the delivery of video, providing a quality of service that over-the-top Internet video providers simply can't match. And, while cable systems are aggressively moving towards next generation interactive platforms, application developers continue to struggle with legacy limitations and long, complex development and integration cycles. The number of different set-top box models in the field requires programmers to author multiple versions of each application or to restrict features to the least capable client. Application designs are often constrained by the number of available tuners, insufficient processor and memory capacity, on-screen graphics display capabilities and the network infrastructure's ability to deliver and manage large amounts of media and graphics. 

ActiveVideo operates differently than traditional interactive television applications. In fact, ActiveVideo applications are so different that it is more accurate to think of them as interactive programming. Instead of relying on set-top box hardware and software to execute and render an application, the user interface and navigation are embedded in the programming itself, allowing applications to be as rich and complex as the programmer can imagine. 

ActiveVideo components

The ActiveVideo Platform supports the entire application lifecycle from content creation and distribution through deployment and real-time operation and monitoring. The platform consists of three logical subsystems.

ActiveVideo Editor
ActiveVideo Set-Top Box Client
ActiveVideo Distribution Network (AVDN)

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