USB 2.0 vs USB 3.0

USB 3.0, the latest version of USB (Universal Serial Bus), provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate.

Comparison chart

	USB 2.0	USB 3.0
Released:	April 2000	November 2008
Speed:	High Speed or HS, 480 Mbps (Megabits per second)	10 times faster than USB 2.0. Super Speed or SS, 4.8 Gbps (Giga bits per second)
Signaling Method:	Polling mechanism i.e can either send or receive data	Asynchronous mechanism i.e. can send and receive data simultaneously
Price:	For a similar product, the USB 2.0 version is generally less expensive than it's USB 3.0 version.	For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.
Power Usage:	Up to 500 mA	Up to 900 mA. Allows better power efficiency with less power for idle states. Can power more devices from one hub.
Number of wires within the cable:	4	8
Standard-A Connectors:	Grey in color	Blue in color
Standard-B Connectors:	Smaller in size	Extra space for more wires

What is USB 3.0 and USB 2.0?

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. Now even devices like smartphones, PDAs and video game consoles are connected to the computers with USB ports allowing recharging and communication thereby replacing the requirement of adapters and power chargers.

USB3.0 was released in November 2008, almost eight years after the release of USB 2.0.

USB 3.0 Highlights and Benefits over USB 2.0                

• Transfer rates - USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps - that's 10 times faster.
• Addition of another phsyical bus - The amount of wires has been doubled, from 4 to 8. Additional wires require more space in both the cables and connectors, so there are new types of connectors.
• Power consumption - USB 2.0 provides up to 500 mA whereas USB 3.0 provides up to 900 mA. The USB 3 devices will provide more power when needed and conserve power when the device is connected but idling.
• More bandwidth - instead of one-way communication, USB 3.0 uses two unidirectional data paths, one to receive data and the other to transmit while USB 2.0 can only handle only one direction of data at any time.
• Improved bus utilization - a new feature has been added (using packets NRDY and ERDY) to let a device asynchronously notify the host of its readiness.

When data is being transferred through USB 3.0 Devices, cables and connectors transaction is initiated by the host making a request followed by a response from the device. The device either accepts the request or rejects it. If accepted then device sends data or accepts data from the host. If there is lack of buffer space or data, it responds with a Not Ready (NRDY) signal to tell the host that it is not able to process the request. When the device is ready then, it will send an Endpoint Ready (ERDY) to the host which will then reschedule the transaction.

Physical Differences                                                                    

USB 3.0 Connectors are different from USB 2.0 Connectors and the 3.0 connectors are usually colored blue on the inside in order to distinguish them from the 2.0 connectors.

Various types of USB Connectors (click to enlarge). From Left to Right: Micro USB Type AB, Micro USB Type B, USB 2.0 Type A, USB 2.0 Type B, USB 3.0 Type A, USB 3.0 Type B, USB 3.0 Type Micro B, Min USB Type A connector

Backward Compatible                                                                

USB 3.0 is compatible with USB 2.0. However, the USB 3.0 product will perform at the same level as a USB 2.0 product, so speed and power benefits will not be fully realized.

USB 3.0 receptacles are electrically compatible with USB Standard 2.0 device plugs if they physically match. USB 3.0 type-A plugs and receptacles are completely backward compatible, and USB 3.0 type-B receptacles will accept USB 2.0 and earlier plugs. However, USB 3.0 type-B plugs will not fit into USB 2.0 and earlier receptacles.

This means that USB 3.0 cables cannot be used with USB 2.0 and USB 1.1 peripherals, although USB 2.0 cables can be used with USB 3.0 devices, if at USB 2.0 speeds. 

Price

For a similar product, the USB 3.0 version is generally more expensive than it's USB 2.0 version.

3G Vs. 4G

How much faster is 4G compared to 3G and what applications run better on 4G?

3G and 4G are standards for mobile communication. Standards specify how the airwaves must be used for transmitting information (voice and data). 3G (or 3rd Generation) was launched in Japan in 2001. As recently as mid-2010, the networks for most wireless carriers in the U.S. were 3G. 3G networks were a significant improvement over 2G networks, offering higher speeds for data transfer. The improvement that 4G offers over 3G is often less pronounced. Analysts use the analogy of standard vs Hi-Def TV to describe the difference between 3G and 4G.

Comparison chart:

	3G	4G
Data Throughput:	Up to 3.1mbps	Practically speaking, 3 to 5 mbps but potential estimated at a range of 100 to 300 mbps.
Peak Upload Rate:	50 Mbit/s	500 Mbit/s
Peak Download Rate:	100 Mbit/s	1 Gbit/s
Switching Technique:	packet switching	packet switching, message switching
Network Architecture:	Wide Area Cell Based	Integration of wireless LAN and Wide area.
Services And Applications:	CDMA 2000, UMTS, EDGE etc	Wimax2 and LTE-Advance
Forward error correction (FEC):	3G uses Turbo codes for error correction.	Concatenated codes are used for error corrections in 4G.
Frequency Band:	1.8 – 2.5GHz	2 – 8GHz

Comparison Between A-GPS and GPS

 

A-GPS and GPS are different navigational aids that both use information from satellites to determine their exact location on Earth.

GPS stands for Global Positioning System. A GPS device communicates with 4 or more satellites to determine its exact location coordinates (latitude and longitude) anywhere on Earth. It works in any weather as long as the device has a clear line of sight to the satellites.

A-GPS stands for Assisted Global Positioning System. While it works on the same principles as a GPS (explained below), the difference here is that it gets the information from the satellites by using network resources e.g. mobile network, also called assistant servers.

Comparison chart

	A-GPS	GPS
Stands for:	Assisted Global Positioning System	Global Positioning System
Source of triangulation information:	Radio signals from satellites and assistance servers e.g. mobile network cell sites	Radio signals from GPS satellites
Speed:	A-GPS devices determine location coordinates faster because they have better connectivity with cell sites than directly with satellites.	GPS devices may take several minutes to determine their location because it takes longer to establish connectivity with 4 satellites.
Reliability:	Location determined via A-GPS are slightly less accurate than GPS	GPS devices can determine location coordinates to within 1 meter accuracy
Cost:	It costs money to use A-GPS devices on an ongoing basis because they use mobile network resources.	GPS devices communicate directly with satellites for free. There is no cost of operation once the device is paid for.
Usage:	Mobile phones	Cars, planes, ships/boats

Difference Between WCDMA and HSPA

WCDMA vs. HSPA

WCDMA stands for Wideband Code Division Multiple Access, a mobile technology that improves upon the capabilities of current GSM networks that are deployed around the world. People commonly refer to this technology as 3G, or 3rd generation, and it provides newer services like video calling to the traditional call, and text messaging features that are already standard. HSPA (High Speed Packet Access) is what is commonly known as 3.5G, as it offers no substantial upgrade to the feature set of WCDMA, but improves the speed of data transmission to enhance those services.

Prior to the introduction of HSPA, WCDMA networks were only capable of reaching speeds of 384kbps. Although this might be sufficient for most services, people always want faster speeds, especially when browsing the internet or downloading files. HSPA allowed speeds above 384kbps, the most notable of which is 3.6Mbps and 7.2Mbps, which a lot of telecommunications companies often advertise. In truth, HSPA is capable of reaching much higher speeds depending on the type of modulation that is being used. HSPA speeds can even reach a theoretical maximum of 84Mbps.

Aside from increasing the existing data speed provided by WCDMA, HSPA also improved the latency, or the time it takes between the moment the request is placed and the moment the requested data is received. The lower latencies provided by HSPA makes the 3G services more real-time, and conversations are more natural. Lower latencies are also good for people who use their connection to play online games, where high latencies result in lag.

Features in HSPA that make these things possible are Fast Packet Scheduling and AMC (Adaptive Modulation and Coding). Fast Packet Scheduling allows the base station to adjust the amount of data that is being transmitted to a certain device based on the current conditions. AMC also allows the base station to select a better modulation and coding scheme if the signal quality allows it. Initially, users are assigned with QPSK, but can be changed to a lot of other coding schemes that provide better data rates if the signal between the device and the base station is strong enough.

Summary:

1. WCDMA is commonly referred to as 3G, while HSPA is commonly referred to as 3.5G.

2. HSPA provides much higher data rates compared to WCDMA.

3. HSPA has lower latency times compared to WCDMA.

4. HSPA has Fast Packet Scheduling and AMC, features that are absent in WCDMA.

Some words on networking

What is Network?

A network or communication network is a system of interconnected communication devices that can communicate with one another and share information. Therefore computer network can be defined as:

'A system in which more than one computers or large number of computers are interconnected together, communicate freely with one another and share information is called computer network.'

A network can be internal to an organization or span the world by connecting itself to the internet. In computer network, network operating system is used that controls and co-ordinates the activities of computers that are connected to the network. The example of these operating systems are: windows NT, UNIX, and Novell etc.

Types of Network

Networks are of three types. These are:

• Local Area Network (LAN)
• Wide Area Network (WAN)
• Metropolitan Area Network (MAN)

Local Area Network

A local area network is a network system in which computers are interconnected in a limited geographical area, such as network of computers in college computer laboratory or network of computers in office building etc.

Have an efficient networking with data center virtualization solutions to provide seamless operation.

Wide Area Network

A wide area network is a network system that covers a large geographical area such as different cities of country or different countries of the world. In WAN telephone lines, satellites, microwave, fiber optic etc. are used as transmission media.

Metropolitan Area Network

A Metropolitan area Network is a network system that covers area of a single city. Usually, MAN connects more than one LANS in a city or town and covers a smaller geographical area than a WAN. The cable television, telephone companies or local corporations use MAN.

Computer Acronyms

ADSL - Asymmetric Digital Subscriber Line
AGP - Accelerated Graphics Port
ALI - Acer Labs, Incorporated
ALU - Arithmetic Logic Unit
AMD - Advanced Micro Devices
APC - American Power Conversion
ASCII - American Standard Code for Information Interchange
ASIC - Application Specific Integrated Circuit
ASPI - Advanced SCSI Programming Interface
AT - Advanced Technology
ATI - ATI Technologies Inc.
ATX - Advanced Technology Extended

--- B ---
BFG - BFG Technologies
BIOS - Basic Input Output System
BNC - Barrel Nut Connector

--- C ---
CAS - Column Address Signal
CD - Compact Disk
CDR - Compact Disk Recorder
CDRW - Compact Disk Re-Writer
CD-ROM - Compact Disk - Read Only Memory
CFM - Cubic Feet per Minute (ft�/min)
CMOS - Complementary Metal Oxide Semiconductor
CPU - Central Processing Unit
CTX - CTX Technology Corporation (Commited to Excellence)

--- D ---

DDR - Double Data Rate
DDR-SDRAM - Double Data Rate - Synchronous Dynamic Random Access Memory
DFI - DFI Inc. (Design for Innovation)
DIMM - Dual Inline Memory Module
DRAM - Dynamic Random Access Memory
DPI - Dots Per Inch
DSL - See ASDL
DVD - Digital Versatile Disc
DVD-RAM - Digital Versatile Disk - Random Access Memory

--- E ---
ECC - Error Correction Code
ECS - Elitegroup Computer Systems
EDO - Extended Data Out
EEPROM - Electrically Erasable Programmable Read-Only Memory
EPROM - Erasable Programmable Read-Only Memory
EVGA - EVGA Corporation

--- F ---
FC-PGA - Flip Chip Pin Grid Array
FDC - Floppy Disk Controller
FDD - Floppy Disk Drive
FPS - Frame Per Second
FPU - Floating Point Unit
FSAA - Full Screen Anti-Aliasing
FS - For Sale
FSB - Front Side Bus

--- G ---
GB - Gigabytes
GBps - Gigabytes per second or Gigabits per second
GDI - Graphical Device Interface
GHz - GigaHertz

--- H ---
HDD - Hard Disk Drive
HIS - Hightech Information System Limited
HP - Hewlett-Packard Development Company
HSF - Heatsink-Fan

--- I ---
IBM - International Business Machines Corporation
IC - Integrated Circuit
IDE - Integrated Drive Electronics
IFS- Item for Sale
IRQ - Interrupt Request
ISA - Industry Standard Architecture
ISO - International Standards Organization

--- J ---
JBL - JBL (Jame B. Lansing) Speakers
JVC - JVC Company of America

- K ---
Kbps - Kilobits Per Second
KBps - KiloBytes per second

--- L ---
LG - LG Electronics
LAN - Local Are Network
LCD - Liquid Crystal Display
LDT - Lightning Data Transport
LED - Light Emitting Diode

--- M ---
MAC - Media Access Control
MB � MotherBoard or Megabyte
MBps - Megabytes Per Second
Mbps - Megabits Per Second or Megabits Per Second
MHz - MegaHertz
MIPS - Million Instructions Per Second
MMX - Multi-Media Extensions
MSI - Micro Star International

--- N ---
NAS - Network Attached Storage
NAT - Network Address Translation
NEC - NEC Corporation
NIC - Network Interface Card

--- O ---
OC - Overclock (Over Clock)
OCZ - OCZ Technology
OEM - Original Equipment Manufacturer

--- P ---
PC - Personal Computer
PCB - Printed Circuit Board
PCI - Peripheral Component Interconnect
PDA - Personal Digital Assistant
PCMCIA - Peripheral Component Microchannel Interconnect Architecture
PGA - Professional Graphics Array
PLD - Programmable Logic Device
PM - Private Message / Private Messaging
PnP - Plug 'n Play
PNY - PNY Technology
POST - Power On Self Test
PPPoA - Point-to-Point Protocol over ATM
PPPoE - Point-to-Point Protocol over Ethernet
PQI - PQI Corporation
PSU - Power Supply Unit

--- R ---
RAID - Redundant Array of Inexpensive Disks
RAM - Random Access Memory
RAMDAC - Random Access Memory Digital Analog Convertor
RDRAM - Rambus Dynamic Random Access Memory
ROM - Read Only Memory
RPM - Revolutions Per Minute

--- S ---
SASID - Self-scanned Amorphous Silicon Integrated Display
SCA - SCSI Configured Automatically
SCSI - Small Computer System Interface
SDRAM - Synchronous Dynamic Random Access Memory
SECC - Single Edge Contact Connector
SODIMM - Small Outline Dual Inline Memory Module
SPARC - Scalable Processor ArChitecture
SOHO - Small Office Home Office
SRAM - Static Random Access Memory
SSE - Streaming SIMD Extensions
SVGA - Super Video Graphics Array
S/PDIF - Sony/Philips Digital Interface

--- T ---
TB - Terabytes
TBps - Terabytes per second
Tbps - Terabits per second
TDK - TDK Electronics
TEC - Thermoelectric Cooler
TPC - TipidPC
TWAIN - Technology Without An Important Name

--- U ---
UART - Universal Asynchronous Receiver/Transmitter
USB - Universal Serial Bus
UTP - Unshieled Twisted Pair

--- V ---
VCD - Video CD
VPN - Virtual Private Network

--- W ---
WAN - Wide Area Network
WTB - Want to Buy
WYSIWYG - What You See Is What You Get

--- X ---
XGA - Extended Graphics Array
XFX - XFX Graphics, a Division of Pine
XMS - Extended Memory Specification
XT - Extended Technology

Comparison between IPv4 and IPv6

IPv6 is based on IPv4, it is an evolution of IPv4. So many things that we find with IPv6 are familiar to us. The main differences are:

1.Simplified header format. IPv6 has a fixed length header, which does not include most of the options an IPv4 header can include. Even though the IPv6 header contains two 128 bit addresses (source and destination IP address) the whole header has a fixed length of 40 bytes only. This allows for faster processing.

Options are dealt with in extension headers, which are only inserted after the IPv6 header if needed. So for instance if a packet needs to be fragmented, the fragmentation header is inserted after the IPv6 header. The basic set of extension headers is defined in RFC 2460.

VoIP phones

VoIP phone

VoIP means Voice over Internet Protocol. VoIP phones (or Digital Phones) send voice data in packets over the IP layer. The services they provide are typically the same as the normal phones but the underlying network and the technology are different.

* It might be a dedicated device (like the traditional handset) using IP connection.
* It can also be a normal phone connected to the network through a telephony adapter (TA).
* Else it can be a softphone.

How does VoIP work?

* When you speak at the handset or a mike or a microphone, your voice generates electrical signals inside the gadget. These are analog signals i.e. the voltage level can take up any value within a range.

* The analog signal is converted to a digital signal using an algorithm implemented by the device you are using. It can be a stand-alone VoIP phone or a softphone running on your PC. If you are using an analog phone, you will need a Telephony Adapter (TA) for this purpose. The digitized voice is arranged in packets (i.e. collection of bytes) and sent over the IP network.

* The data is channeled through gateways and servers to the destination. If the called number is on the PSTN, the server opens a connection to the PSTN and routes your call there.

* While going to the PSTN or at the end device of a VoIP connection, the voice is again brought back to its analog form so that it is perceptible to a human ear.

Introduction to VoIP

What is VoIP?

VoIP is the short form of Voice over Internet Protocol. It is also called IP Telephony, Internet telephony or Digital Phone. It utilizes the IP network (Internet or intranets) for telephone conversations. The service it provides is similar as that of normal landline phones but generally offers a cheaper solution. It has some added advantages and as any other service, it faces some challenges too.

How is this useful? VoIP can turn a standard Internet connection into a way to place free phone calls. The practical upshot of this is that by using some of the free VoIP software that is available to make Internet phone calls, you're bypassing the phone company (and its charges) entirely.

Public switched data network

A public switched data network (PSDN) is a publicly-available packet-switched network, distinct from the PSTN.

Originally this term referred only to Packet Switch Stream (PSS), an X.25-based packet-switched network, mostly used to provide leased-line connections between local area networks and the Internet using permanent virtual circuits (PVCs). Today, the term may refer not only to Frame Relay and Asynchronous Transfer Mode (ATM), both providing PVCs, but also to Internet Protocol (IP), GPRS, and other packet-switching techniques.

PSTN (Public Switched Telephone Network)

Definition: PSTN is the global collection of interconnects originally designed to support circuit-switched voice communication. The PSTN provides the traditional Plain Old Telephone Service (POTS) to residences and many other establishments. Parts of the PSTN are also utilized for DSL, VoIP and other Internet-based network technologies.

Switching in computer networks

A network switch or switching hub is a computer networking device that connects network segments.
The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (Layer 3) and above are often referred to as Layer 3 switches or multilayer switches. The term network switch does not generally encompass unintelligent or passive network devices such as hubs and repeaters.