Microformat

From Wikipedia, the free encyclopedia


In web development, a microformat (sometimes abbreviated μF or uF) is a way of adding simple semantic meaning to human-readable content which is otherwise, from a machine's point of view, just plain text. They allow data items such as events, contact details or locations, on HTML (or XHTML) web pages, to be meaningfully detected and the information in them to be extracted by software, and indexed, searched for, saved or cross-referenced, so that it can be reused or combined.

More technically, they are items of semantic mark up, using just standard (X)HTML with a set of common class-names. They are open and available, freely, for anyone to use.

Current microformats allow the encoding and extraction of events, contact information, social relationships, and so on. More are being developed. Version 3 of the Firefox browser, as well as version 8 of Internet Explorer are expected to include native support for microformats.



Principles

(X)HTML standards allow for semantics to be embedded and encoded within them. This is done using specific HTML attributes:

class
rel
rev
For example, 52.48,-1.89 is a pair of numbers which may be understood, from their context, to be a set of geographic coordinates. By wrapping them in spans (or other HTML elements) with specific class names (in this case part of the geo microformat specification):

<span class="geo"><span class="latitude">52.48</span>, <span class="longitude">-1.89</span></span>

machines can be told exactly what each value represents, and can then index it, look it up on a map, export it to a GPS device, etc.


Uses of microformats
-------------------------------------
Using microformats within HTML code provides additional formatting and semantic data that can be used by applications. These could be applications that collect data about on-line resources, such as web crawlers, or desktop applications such as e-mail clients or scheduling software.

Several browser extensions, such as Operator, provide the ability to detect microformats within an HTML document and export them into formats compatible with contact management and calendar utilities, such as Microsoft Outlook.

Microsoft expressed a desire to incorporate Microformats into upcoming projects; as have other software companies.

In Wikipedia - and more generally in MediaWiki - microformats are used as part of templates like {{coord}} for example.

Creation of microformats
----------------------------------------
Most of the existing microformats were created at the microformat wiki and associated mailing list, by a process of gathering examples of web publishing behaviour, then codifying it. Some other microformats (such as rel=nofollow and unAPI have been proposed, or developed, elsewhere.

Read More......

Intel Core 2

From Wikipedia, the free encyclopedia


The Core 2 brand refers to a range of Intel's mobile and desktop 64-bit dual-/quad-core x86 CPUs with the Core microarchitecture, which evolved from the 32-bit dual-core Yonah mobile processor. The Yonah comprised two interconnected single cores (the Pentium M branded microprocessor derivatives) coupled as a single die silicon chip (IC). The Core 2 marked a relegation of the Intel's Pentium brand to a lower-end market, and a reunification of Intel's notebook and desktop brand names, previously divided into the Pentium M and Pentium 4 lines.

The Core 2 brand was launched on July 27, 2006, comprising Duo (dual-core), Quad (quad-core), and Extreme (dual- or quad-core CPUs with higher speeds and unlocked multiplier) branches. The brand covers processors based on various cores; "Conroe" and "Allendale" (dual-core for higher- and lower-end desktop use, respectively), "Merom" (dual-core for notebooks), "Kentsfield" (quad-core for desktops), and their variants named "Penryn" (dual-core for notebooks), "Wolfdale" (dual-core for desktops) and "Yorkfield" (quad-core for desktops). Although the "Woodcrest", "Clovertown" and the upcoming "Tigerton" core CPUs for servers and workstations are also based on Core architecture, they are marketed under the Xeon brand. The first Core 2 Duo processors were fabricated on 300 mm wafers using a 65 nm manufacturing process.


Unlike the NetBurst architecture of Pentium 4 or Pentium D branded processors, the Core architecture does not stress extremely high clock speeds, but rather improvements in the processor's usage of both available clock cycles and power. This translated into more efficient decoding stages, execution units, caches, and buses, etc, reducing the Core 2 CPU's power consumption, while enhancing their processing capacity. With a TDP of up to only 65 W, the Core 2 dual-core Conroe consumed only half the power of some of the higher end dual-core Pentium D branded desktop chips with a TDP of up to 130 W (a high TDP requires many noisy cooling fans or a more expensive noiseless cooling system) and was more capable compared to them.


Intel Core 2 processors featured Intel 64 (also known as EM64T), Virtualization Technology (except T5500 or lower end E4x00), Execute Disable Bit, and SSE3. Core 2 also introduced SSSE3, Trusted Execution Technology, Enhanced SpeedStep, and Active Management Technology (iAMT2).

Typically for CPUs, the Core 2 Duo E4000/E6000, Core 2 Quad Q6600, Core 2 Extreme X6800, QX6700 and QX6800 CPUs were affected by bugs, but apparently minor.

Current processor cores
---------------------------------------------------------------------------------
Conroe
The first Intel Core 2 Duo processor cores, code-named Conroe and given the Intel product code 80557, were launched on July 27, 2006 at Fragapalooza, a yearly gaming event in Edmonton, Alberta, Canada. These processors are built on a 65 nm process and are intended for desktops, replacing the Pentium 4 and Pentium D. Intel has claimed that Conroe provides 40% more performance at 40% less power compared to the Pentium D. All Conroe processors are manufactured with 4 MiB L2 cache; however, for marketing purposes, the E6300 and E6400 versions based on this core have half their cache disabled, leaving them with only 2 MiB of usable L2 cache.

The lower end E6300 (1.86 GHz) and E6400 (2.13 GHz), both with a 1066 MT/s FSB, were released on July 27, 2006. Traditionally, CPUs of the same family with less cache simply have the unavailable cache disabled, since this allows parts that fail quality control to be sold at a lower rating. As yields improve, they may be replaced with versions that only have the cache amount needed on the die, to bring down manufacturing cost. At launch time, Intel's prices for the Core 2 Duo E6300 and E6400 processors were US$183 and US$224 each in quantities of 1000. Conroe CPUs have improved capabilities over previous models with similar processor speeds. According to reviews, the larger 4 MiB L2 cache vs. the smaller 2 MiB L2 cache at the same frequency and FSB can provide a 0–9% performance gain with certain applications and 0–16% performance gain with certain games. The higher end Conroe processors are labeled as the E6600 and E6700 Core 2 Duo models, with the E6600 clocked at 2.4 GHz and the E6700 clocked at 2.67 GHz. The family has a 1066 MT/s front side bus, 4 MiB shared L2 cache, and 65 watts TDP. These processors have been tested against AMD's current top performing processors (Athlon 64 FX Series), which were, until this latest Intel release, the fastest CPUs available. Conroe chips also experience much lower heat output compared to their predecessors — a benefit of the new 65 nm technology. At launch time, Intel's prices for the Core 2 Duo E6600 and E6700 processors were US$316 and US$530, respectively, each in quantities of 1000.

E6320 and E6420 Conroe CPUs at 1.86 and 2.13 GHz respectively were launched on April 22, 2007 featuring a full 4 MiB of cache and are considered Conroes.

Intel released four additional Core 2 Duo Processors on July 22nd, 2007. The release coincided with that of the Intel Bearlake (x3x) chipsets. The new processors are named Core 2 Duo E6540, E6550, E6750, and E6850. Processors with a number ending in "50" have a 1333 MT/s FSB. The processors all have 4 MiB of L2 cache. Their clock frequency is similar to that of the already released processors with the same first two digits (E6600, E6700, X6800). An additional model, the E6540, was launched with specifications similar to the E6550 but lacking Intel Trusted Execution Technology and vPro support. These processors are slated to compete with AMD's Stars processor line and are therefore priced below corresponding processors with a 1066 MT/s FSB.

Conroe XE
The Core 2 Extreme was officially released on July 29, 2006. However some retailers appeared to have released it on July 13, 2006, though at a higher premium. The less powerful E6x00 models of Core 2 Duo were scheduled for simultaneous release with the X6800, which are both available at this time. It is powered by the Conroe XE core and replaces the dual-core Pentium Extreme Edition processors. Core 2 Extreme has a clock speed of 2.93 GHz and a 1066 MT/s FSB, although it was initially expected to be released with a 3.33 GHz and 1333 MT/s. The TDP for this family is 75–80 watts. At full load the X6800 does not exceed 45 °C (113 °F), and with SpeedStep enabled the average temperature of the CPU when idle is essentially that of the ambient atmosphere.

At launch time, Intel's price for the Core 2 Extreme X6800 was US$999 each in quantities of 1000. Like the desktop Core 2 Duo, it has 4 MiB of shared L2 cache available. This means that the only major difference between the regular Core 2 Duo and Core 2 Extreme is the clock speed and unlocked multiplier, usual advantages of the "Extreme Edition." The unlocked upward multiplier is of use to enthusiasts which allow the user to set the clockspeed higher than shipping frequency without modifying the FSB unlike mainstream Core 2 Duo models which are downward unlocked only.

Allendale
There was contention as to whether the previously-available low-end Core 2 Duo desktop processors (E6300, at 1.86 GHz and E6400, at 2.13 GHz, both with 2 MiB L2 cache) are specimens of the Allendale core. Prior to Q1 2007, all E6300 and E6400 processors released were Conroe (4 MiB L2 cache) cores with half their L2 cache disabled. The Allendale core, manufactured with 2 MiB L2 cache in total, offers a smaller die size and therefore greater yields.

Quoted from The Tech Report:

You'll find plenty of sources that will tell you the code name for these 2 MB Core 2 Duo processors is "Allendale," but Intel says otherwise. These CPUs are still code-named "Conroe," which makes sense since they're the same physical chips with half of their L2 cache disabled. Intel may well be cooking up a chip code-named Allendale with 2 MB of L2 cache natively, but this is not that chip.

Another difference between the premium E6000 series (Conroe core) or (Allendale core) and the E4000 series (Allendale core) is the front side bus clock rating. The E4000 series are rated to run on a quad-pumped 200 MHz front side bus ("800 MT/s") while the E6000 series are rated to run on a quad-pumped 266 MHz front side bus ("1066 MT/s"). The E4000 series also lack support for Intel VT-x instructions.

The currently available Core 2 Duo E4300 only uses an Allendale core, released on January 21, 2007. The Allendale processors use a smaller mask with only 2 MiB of cache, thereby increasing the number of chips per wafer. Allendale processors are produced in the LGA775 form factor, on the 65 nm process node. It is unclear and a matter of contention whether the E6300 and E6400 models are still Conroe processors with half their L2 cache disabled or Allendale processors. It is possible that the E6300 and E6400 models can be both Allendale and Conroe, differentiated by the L2 and B2 steppings respectively.

Initial list price per processor in quantities of one thousand for the E4300 was US$163. A standard OEM price was US$175, or US$189 for a retail package. Price cuts were enacted on April 22, 2007, when the E4400 was released at $133 and the E4300 dropped to $113. Allendale processors with half their L2 cache disabled were released in mid-June 2007 under the Pentium Dual-Core brand name.

On July 22nd, 2007, an E4500 Allendale was launched, phasing out the E4300 model. This was accompanied by a price cut for the E4400 model.


Merom
Merom, the first mobile version of the Core 2, was officially released on July 27, 2006 but quietly began shipping to PC manufacturers in mid-July alongside Conroe. Merom is Intel's premier line of mobile processors, with largely the same features as Conroe, but with more emphasis on low power consumption to enhance notebook battery life. Merom-based Core 2 Duo provides 20% more performance yet maintains the same battery life as the Yonah-based Core Duo. Merom is the first Intel mobile processor to feature Intel 64 architecture.

The first version of Merom is "drop-in" compatible with Napa platform for Core Duo, requiring at most a motherboard BIOS update. It has a similar thermal envelope of 34 W and the same 667 MT/s FSB rate. Merom features 4 MiB L2 cache (budget T5xxx models have only 2 MiB L2 cache).

A second wave of Merom processors featuring an 800 MT/s FSB and using the new Socket P was launched on May 9, 2007. These chips are part of Santa Rosa platform. Low voltage versions were also released on May 9, 2007.

Merom (מרום) is the Hebrew word for a higher plane of existence or a level of heaven, BaMerom (במרום) means "in the heavens". The name was chosen by the Intel team in Haifa, Israel, who designed this processor.

See the Merom section of "List of Intel Core 2 microprocessors" for a list of Merom processors.

Kentsfield
The Kentsfield was the first Intel desktop quad core CPU branded as Core 2 (and Xeon for lower-end servers and workstations). The top-of-the-line Kentsfields were Core 2 Extreme models numbered QX6xx0, while the mainstream ones branded Core 2 Quad were numbered Q6xx0. All of them featured two 4 MB L2 caches. The mainstream Core 2 Quad Q6600, clocked at 2.4 GHz, was launched on January 8, 2007 at US$851 (reduced to US$530 on April 7, 2007, and to US$266 on July 22, 2007). July 22, 2007 marked the release of the next Core 2: Quad Q6700 and Extreme QX6850 Kentsfields at US$530 and US$999 respectively, and also price reduction of Core 2: Quad Q6600 and Extreme QX6800 Kentsfields to US$266 and US$999 respectively.

Kentsfield, like the Pentium D Presler, comprised two separate silicon dies. Each of Kentsfield's two dies was dual-core with the Core architecture, as did each die constituting alone every Core 2's dual-core only CPU. Hence, the max. power consumption (TDP) of the Kensfield (QX6800 - 130 watts, QX6700 - 130 W,Q6600 - 95 W) was approx. double of its similarly clocked Core 2 Duo counterpart. For example, the QX6700 consisted of two E6700 chips connected together by a 1066 MT/s FSB on one MCM, resulting in lower costs but less bandwidth to the northbridge. The Kentsfield was one socket processor sitting in a LGA775 socket, as well as Core 2 Duo (AMD Quad FX consisted of two dual-core processors in two separate sockets on one motherboard with a 2 x 125 W= 250 W TDP).

A quad-core CPU, like the Kentsfield, processes very well with multi-threaded applications (typical for video editing, ray-tracing, or rendering), where its processing ability may approach double that of each of its halves comprising the equally clocked dual-core CPU. Similarly, Pentium D Presler had two dice in one package. A two-die CPU, however, can rarely double the processing ability of each of its constituent halves (e.g. the Kentsfield rarely doubles the ability of the Conroe), due to a loss of performance resulting from connecting them (i.e. sharing the narrow memory bandwidth, and operating system overhead of handling twice as many cores and threads).

Single or dual-threaded applications alone, including most games, do not benefit from the second pair of cores of a quad-core CPU over an equally clocked dual-core CPU. For example, with no increase in FSB speed and a mild reduction in processor frequency of the quad-core Extreme QX6700 over the older dual-core Extreme X6800, overall performance of the Kentsfield (QX6700) for those applications does not improve. Nevertheless, the simultaneous use of several processor-intensive single/dual-threaded applications on a quad-core CPU will generally lead to a dramatic overall performance increase over an equally clocked dual-core CPU. A quad-core CPU is useful also to run the both client and server processes of a game without noticeable lag in either thread, as each instance (up to four) could be running on a different core.

Kentsfield XE
The first Kentsfield, named Core 2 Extreme QX6700 (product code 80562) and clocked at 2.67 GHz, was released on November 2, 2006 at US$999. It was the first x86 quad-core processor ever, featured the Kentsfield XE core, and complemented the Core 2 Extreme X6800 dual-core processor based on the Conroe XE core. The CPUs with the Kentsfield XE core had the highest and unlocked multipliers like their Extreme predecessors. On April 8, 2007, a new top Kentsfield XE - the Core 2 Extreme QX6800 - was released within the 135 W TDP thermal envelope, and clocked at 2.93 GHz. It went to high end OEM-only systems at US$1,199. On July 22, 2007, the new champ Core 2 Extreme QX6850 arrived, clocked at 3.0 GHz, with a faster 1.33 GHz FSB, and at US$999 - a typical price for a top Kentsfield XE CPU.

The formerly available Core 2 Extreme QX6700 was relaunched on July 22nd, 2007 as the Core 2 Quad Q6700, clocked at 2.66 GHz, but it consumes less power than QX6700. The price of the Q6600 has been dropped to US$266 on July 22nd, 2007.

Read More......

RSS

From Wikipedia, the free encyclopedia

RSS (which, in its latest format, stands for "Really Simple Syndication") is a family of web feed formats used to publish frequently updated content such as blog entries, news headlines or podcasts. An RSS document, which is called a "feed", "web feed", or "channel", contains either a summary of content from an associated web site or the full text. RSS makes it possible for people to keep up with their favorite web sites in an automated manner that's easier than checking them manually.

RSS content can be read using software called a "feed reader" or an "aggregator." The user subscribes to a feed by entering the feed's link into the reader or by clicking an RSS icon in a browser that initiates the subscription process. The reader checks the user's subscribed feeds regularly for new content, downloading any updates that it finds.

The initials "RSS" are used to refer to the following formats:

Really Simple Syndication (RSS 2.0)
RDF Site Summary (RSS 1.0 and RSS 0.90)
Rich Site Summary (RSS 0.91)
RSS formats are specified using XML, a generic specification for the creation of data formats.



Incompatibilities
------------------------------------
As noted above, there are several different versions of RSS, falling into two major branches (RDF and 2.*). The RDF, or RSS 1.* branch includes the following versions:

-RSS 0.90 was the original Netscape RSS version. This RSS was called RDF Site Summary, but was based on an early working draft of the RDF standard, and was not compatible with the final RDF Recommendation.
-RSS 1.0 is an open format by the RSS-DEV Working Group, again standing for RDF Site Summary. RSS 1.0 is an RDF format like RSS 0.90, but not fully compatible with it, since 1.0 is based on the final RDF 1.0 Recommendation.
-RSS 1.1 is also an open format and is intended to update and replace RSS 1.0. The specification is an independent draft not supported or endorsed in any way by the RSS-Dev Working Group or any other organization.
The RSS 2.* branch (initially UserLand, now Harvard) includes the following versions:

-RSS 0.91 is the simplified RSS version released by Netscape, and also the version number of the simplified version championed by Dave Winer from Userland Software. The Netscape version was now called Rich Site Summary, this was no longer an RDF format, but was relatively easy to use. It remains the most common RSS variant.
-RSS 0.92 through 0.94 are expansions of the RSS 0.91 format, which are mostly compatible with each other and with Winer's version of RSS 0.91, but are not compatible with RSS 0.90. In all Userland RSS 0.9x specifications, RSS was no longer an acronym.
-RSS 2.0.1 has the internal version number 2.0. RSS 2.0.1 was proclaimed to be "frozen", but still updated shortly after release without changing the version number. RSS now stood for Really Simple Syndication. The major change in this version is an explicit extension mechanism using XML Namespaces.
For the most part, later versions in each branch are backward-compatible with earlier versions (aside from non-conformant RDF syntax in 0.90), and both versions include properly documented extension mechanisms using XML Namespaces, either directly (in the 2.* branch) or through RDF (in the 1.* branch). Most syndication software supports both branches. Mark Pilgrim's article "The Myth of RSS Compatibility" discusses RSS version compatibility in more detail.

The extension mechanisms make it possible for each branch to track innovations in the other. For example, the RSS 2.* branch was the first to support enclosures, making it the current leading choice for podcasting, and as of mid-2005 is the format supported for that use by iTunes and other podcasting software; however, an enclosure extension is now available for the RSS 1.* branch, mod_enclosure. Likewise, the RSS 2.* core specification does not support providing full-text in addition to a synopsis, but the RSS 1.* markup can be (and often is) used as an extension. There are also several common outside extension packages available, including a new proposal from Microsoft for use in Internet Explorer 7.

The most serious compatibility problem is with HTML markup. Userland's RSS reader—generally considered as the reference implementation—did not originally filter out HTML markup from feeds. As a result, publishers began placing HTML markup into the titles and descriptions of items in their RSS feeds. This behavior has become widely expected of readers, to the point of becoming a de facto standard, though there is still some inconsistency in how software handles this markup, particularly in titles. The RSS 2.0 specification was later updated to include examples of entity-encoded HTML, however all prior plain text usages remain valid.

Atom
------------------------------------
In reaction to recognized issues with RSS (and because RSS 2.0 is frozen), a third group began a new syndication specification, Atom, in June 2003. Their work was later adopted by the Internet Engineering Task Force (IETF) leading to the publication of a specification (RFC 4287) for the Atom Format in 2005. Work on the Atom Publishing Protocol, a standards-based protocol for posting to publishing tools is ongoing.

The relative benefits of Atom in comparison to the two RSS branches are a matter of debate within the Web-syndication community. Supporters of Atom claim that it improves on RSS by relying on standard XML features, by specifying a payload container that can handle many different kinds of content unambiguously, and by having a specification maintained by a recognized standards organization. Critics claim that Atom unnecessarily introduces a third branch of syndication specifications, further confusing the marketplace.

Atom aims to define both a syntax and a protocol for updating user blogs and thus goes beyond the simple remit of RSS. While this is appealing to many users, particularly those in the blogging community, it has been met with resistance in the professional community (mainly publishers) due to its lack of extensibility.

For a comparison of Atom 1.0 to RSS 2.0 see Atom Compared to RSS 2.0.

BitTorrent and RSS
------------------------------------
The peer-to-peer application BitTorrent has also announced support for RSS. Such feeds (also known as Torrent/RSS-es or Torrentcasts) will allow client applications to download files automatically from the moment the RSS reader detects them (also known as Broadcatching). Most common BitTorrent clients already offer RSS support

Read More......

WiMAX

From Wikipedia, the free encyclopedia


WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology aimed at providing wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is based on the IEEE 802.16 standard, which is also called WirelessMAN. WiMAX allows a user, for example, to browse the Internet on a laptop computer without physically connecting the laptop to a wall jack. The name WiMAX was created by the WiMAX Forum, which was formed in June 2001 to promote conformance and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL."



Uses
------------------------------------
The bandwidth and reach of WiMAX make it suitable for the following potential applications:

-Connecting Wi-Fi hotspots with each other and to other parts of the Internet.
-Providing a wireless alternative to cable and DSL for last mile (last km) broadband access.
-Providing high-speed data and telecommunications services.
-Providing a diverse source of Internet connectivity as part of a business continuity plan. That is, if a business has a fixed and a wireless Internet connection, especially from unrelated providers, they are unlikely to be affected by the same service outage.
-Providing nomadic connectivity.

Broadband access
Many companies are closely examining WiMAX for "last mile" connectivity at high data rates. The resulting competition may bring lower pricing for both home and business customers, or bring broadband access to places where it has been economically unavailable. Prior to WiMAX, many operators have been using proprietary fixed wireless technologies for broadband services.

WiMAX access was used to assist with communications in Aceh, Indonesia, after the tsunami in December 2004. All communication infrastructures, other than HAM Radio in the area were destroyed making the survivors unable to communicate with people outside the disaster area and vice versa. WiMAX provided broadband access that helped regenerate communication to and from Aceh.

Subscriber units
WiMAX subscriber units are available in both indoor and outdoor versions from several manufacturers. Self-install indoor units are convenient, but radio losses mean that the subscriber must be significantly closer to the WiMAX base station than with professionally installed external units. As such, indoor installed units require a much higher infrastructure investment as well as operational cost (site lease, backhaul, maintenance) due to the high number of base stations required to cover a given area. Indoor units are comparable in size to a cable modem or DSL modem. Outdoor units are roughly the size of a laptop PC, and their installation is comparable to a residential satellite dish.

With the advent of mobility ("16e"), there is an increasing focus on portable units. This includes handsets (similar to cellular smartphones) and PC peripherals (PC Cards or USB dongles). In addition, there is much emphasis from operators on consumer electronics devices (games terminals, MP3 players and the like); it is notable this is more similar to WiFi than 3G cellular technologies.

Mobile applications
Some cellular companies are evaluating WiMAX as a means of increasing bandwidth for a variety of data-intensive applications; Sprint Nextel announced in mid-2006 that it would invest about US$ 3 billion in a WiMAX technology buildout over the next few years.

In line with these possible applications is the technology's ability to serve as a high bandwidth "backhaul" for Internet or cellular phone traffic from remote areas back to an Internet backbone. Although the cost per user/point of WiMAX in a remote application will be higher, it is not limited to such applications, and may be an answer to reducing the cost of T1/E1 backhaul as well. Given the limited wired infrastructure in some developing countries, the costs to install a WiMAX station in conjunction with an existing cellular tower or even as a solitary hub are likely to be small in comparison to developing a wired solution. Areas of low population density and flat terrain are particularly suited to WiMAX and its range. For countries that have skipped wired infrastructure as a result of prohibitive costs and unsympathetic geography, WiMAX can enhance wireless infrastructure in an inexpensive, decentralized, deployment-friendly and effective manner.

Standards
------------------------------------
The current WiMAX incarnation, Mobile WiMAX, is based upon IEEE Std 802.16e-2005, approved in December 2005. It is an amendment of IEEE Std 802.16-2004 and so the actual standard is 802.16-2004 as amended by 802.16e-2005 - the specifications need to be read together to understand them.

IEEE Std 802.16-2004 addresses only fixed systems. It replaced IEEE Standards 802.16-2001, 802.16c-2002, and 802.16a-2003.

IEEE 802.16e-2005
IEEE 802.16e-2005 improves upon IEEE 802.16-2004 by:

-Scaling of the Fast Fourier Transform (FFT) to the channel bandwidth in order to keep the carrier spacing constant across different channel bandwidths (1.25-20 MHz). Constant carrier spacing results in a higher spectrum efficiency in wide channels, and a cost reduction in narrow channels. Also known as Scalable OFDMA (SOFDMA).
-Improving NLOS coverage by utilizing advanced antenna diversity schemes, and hybrid-Automatic Retransmission Request (hARQ)
-Improving capacity and coverage by introducing Adaptive Antenna Systems (AAS) and Multiple Input Multiple Output (MIMO) technology
-Increasing system gain by use of denser sub-channelization, thereby improving indoor penetration
-Introducing high-performance coding techniques such as Turbo Coding and Low-Density Parity Check (LDPC), enhancing security and NLOS performance
-Introducing downlink sub-channelization, allowing administrators to trade coverage for capacity or vice versa
-Enhanced Fast Fourier Transform algorithm can tolerate larger delay spreads, increasing resistance to multipath interference
-Adding an extra QoS class (enhanced real-time Polling Service) more appropriate for VoIP applications.
-Adding support for mobility (soft and hard handover between base stations). This is seen as one of the most important aspects of 802.16e-2005, and is the very basis of 'Mobile WiMAX'.
802.16d vendors point out that fixed WiMAX offers the benefit of available commercial products and implementations optimized for fixed access. It is a popular standard among alternative service providers and operators in developing areas due to its low cost of deployment and advanced performance in a fixed environment. Fixed WiMAX is also seen as a potential standard for backhaul of wireless base stations such as cellular, WiFi or even Mobile WiMAX.

SOFDMA (used in 802.16e-2005) and OFDM256 (802.16d) are not compatible so most equipment will have to be replaced if an operator wants or needs to move to the later standard. However, some manufacturers are planning to provide a migration path for older equipment to SOFDMA compatibility which would ease the transition for those networks which have already made the OFDM256 investment. This affects a relatively small number users and operators.

WiBro
South Korea's electronics and telecommunication industry spearheaded by Samsung Electronics and ETRI has developed its own standard, WiBro. In late 2004, Intel and LG Electronics have agreed on a merger of mobile WiBro(S-OFDMA modulation) and fixed WiMAX(OFDM modulation) to produce a new standard dubbed Mobile WiMax(802.16e-2005) combining features from both to avoid a future standard war. From this point on WiBro became a specific subset implementation of 802.16e-2005 standard over 8.75 Mhz channels in 2.3 Ghz band, whereas Mobile WiMax represents a full implementation of 802.16e-2005 standard that supports flexible channel size and service band. The side effect of this merger is that Mobile WiMax gears are backward compatible with WiBro gears but not with fixed WiMax gears, reflecting its WiBro originated heritage.

WiBro has South Korean government support with the requirement for each carrier to spend over US$1 billion for deployments. Korea sought to develop WiBro as a regional and potentially international alternative to 3.5G or 4G cellular systems. But given the lack of momentum as a standard, WiBro has joined WiMAX and agreed to harmonize with the similar OFDMA 802.16e version of the standard.

What makes WiBro roll-outs a good "test case" for the overall WiMAX effort is that it is mobile, well thought out for delivery of wireless broadband services, and the fact that the deployment is taking place in a highly sophisticated, broadband-saturated market. WiBro will go up against 3G and very high bandwidth wire-line services rather than as gap-filler or rural under-served market deployments often thought of as "best fit" markets for WiMAX.

As such, WiBRO is now best described as a particular profile within WiMAX with 8.75MHz channel in the 2.3GHz band.

Read More......