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Evolution-Data Optimized or Evolution-Data only

Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or and often EVDOEV, is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. It uses multiplexing techniques including Code division multiple access (CDMA) as well as Time division multiple access (TDMA) to maximize both individual user's throughput and the overall system throughput. It is standardized by 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and has been adopted by many mobile phone service providers around the world – particularly those previously employing CDMA networks. It is also used on the Globalstar satellite phone network.

EV-DO was designed as an evolution of the CDMA2000 (IS-2000) standard that would support high data rates and could be deployed alongside a wireless carrier's voice services. An EV-DO channel has a bandwidth of 1.25 MHz, the same bandwidth size that IS-95A (IS-95) and IS-2000 (1xRTT) use. The channel structure, on the other hand, is very different. Additionally, the back-end network is entirely packet-based, and thus is not constrained by the restrictions typically present on a circuit switched network.

The EV-DO feature of CDMA2000 networks provides access to mobile devices with forward link air interface speeds of up to 2.4 Mbit/s with Rev. 0 and up to 3.1 Mbit/s with Rev. A. The reverse link rate for Rev. 0 can operate up to 153 kbit/s, while Rev. A can operate at up to 1.8 Mbit/s. It was designed to be operated end-to-end as an IP based network, and so it can support any application which can operate on such a network and bit rate constraints.

Standard revisions

There have been several revisions of the standard, starting with Revision 0 (Rev. 0). This was later expanded upon with Revision A to support QoS (to improve latency) and higher rates on the forward link and reverse link. Later in 2006 Revision B was published, that among other features includes the ability to bundle multiple carriers to achieve even higher rates and lower latencies (see TIA-856 Rev. B below). The upgrade from EV-DO Rev. A to EV-DO Rev. B involves a software update to the cell site modem, and additional equipment for the new EV-DO carriers. Existing cdma2000 operators may also have to retune some of their existing 1xRTT channels to other frequencies, since Rev. B requires all DO carriers be within 5 MHz.

TIA-856 Revision 0

The initial design of EV-DO was developed by Qualcomm in 1999 to meet IMT-2000 requirements for a greater-than-2-Mbit/s down link for stationary communications, as opposed to mobile communication such as a moving cellular phone. Initially, the standard was called High Data Rate (HDR), but was renamed to 1xEV-DO after it was ratified by the International Telecommunication Union (ITU); it was given the numerical designation TIA-856. Originally, 1xEV-DO stood for "1x Evolution-Data Only", referring to its being a direct evolution of the 1x (1xRTT) air interface standard, with its channels carrying only data traffic. The title of the 1xEV-DO standard document is "cdma2000 High Rate Packet Data Air Interface Specification", as cdma2000 (lowercase) is another name for the 1x standard, numerically designated as TIA-2000.

Later, likely due to the possible negative connotations of the word "only", the "DO" part of the standard's name 1xEV-DO was changed to stand for "Data Optimized". So EV-DO now stands for "Evolution-Data Optimized", the 1x prefix has been dropped by the many major carriers, and is marketed simply as EV-DO. This provides a more marketing-friendly emphasis that the technology was optimized for data.

TIA-856 Rev. 0 forward link channel structure

The primary characteristic that differentiates an EV-DO channel from a 1xRTT channel is that it is Time Multiplexed on the forward link (from the tower to the mobile). This means that a single mobile has full use of the forward traffic channel within a particular geographic area (a sector) during a given slot of time. Using this technique, EV-DO is able to modulate each user’s time slot independently. This allows the service of users that are in favorable RF conditions with very complex modulation techniques while also serving users in poor RF conditions with simpler and more redundant signals.

The forward channel is divided into slots, each being 1.667 ms long. In addition to user traffic, overhead channels are interlaced into the stream. These include the Pilot which helps the mobile find and identify the channel, the Media Access Channel (MAC) which tells the mobiles when their data is scheduled, and the Control Channel, which contains other information that the network needs the mobiles to know.

The modulation to be used to communicate with a given mobile is determined by the mobile itself. It listens to the traffic on the channel, and depending on the receive signal strength along with the perceived multi-path and fading conditions, makes its best guess as to what data-rate it can sustain while maintaining a reasonable frame error rate of 1-2%. It then communicates this information back to the serving sector in the form of an integer between 1 and 12 on the "Digital Rate Control" (DRC) channel. Alternatively, the mobile can select a "null" rate (DRC 0), indicating that the mobile either cannot decode data at any rate, or that it is attempting to hand off to another serving sector.

The DRC values are as follows:













Another important aspect of the EV-DO forward link channel is the scheduler. The scheduler most commonly used is called "proportional fair". It's designed to maximize sector throughput while also guaranteeing each user a certain minimum level of service. The idea is to schedule mobiles reporting higher DRC indices more often, with the hope that those reporting worse conditions will improve in time.

The system also incorporates Incremental Redundancy Hybrid ARQ. Each sub-packet of a multi-slot transmission is a turbo-coded replica of the original data bits. This allows mobiles to acknowledge a packet before all of its sub-sections have been transmitted. For example, if a mobile transmits a DRC index of 3 and is scheduled to receive data, it will expect to get data during four time slots. If after decoding the first slot the mobile is able to determine the entire data packet, it can send an early acknowledgement back at that time; the remaining three sub-packets will be cancelled. If however the packet is not acknowledged, the network will proceed with the transmission of the remaining parts until all have been transmitted or the packet is acknowledged.

TIA-856 Rev. 0 reverse link structure

The reverse link (from the mobile back to the Base Transceiver Station) on EV-DO Rev. 0 operates very similar to that of 3G1X CDMA. The channel includes a reverse link pilot (helps with decoding the signal) along with the user data channels. Some additional channels that do not exist in 3G1X include the DRC channel (described above) and the ACK channel (used for HARQ). Only the reverse link has any sort of Power control, because the forward link is always transmitted at full power for use by all the mobiles. The reverse link has both open loop and closed loop power control. In the open loop, the reverse link transmission power is set based upon the received power on the forward link. In the closed loop, the reverse link power is adjusted up or down 800 times a second, as indicated by the serving sector (similar to 3G1X).

All of the reverse link channels are combined using code division and transmitted back to the base station using QPSK where they are decoded. The maximum speed available for user data is 153.2 kbit/s, but in real-life conditions this is rarely achieved. Typical speeds achieved are between 20-50 kbit/s.

TIA-856 Rev. A

Revision A of EV-DO makes several additions to the protocol while keeping it completely backwards compatible with Revision 0.

These changes included the introduction of several new forward link data rates that increase the maximum burst rate from 2.45 Mbit/s to 3.1 Mbit/s. Also included were protocols that would decrease connection establishment time (called enhanced access channel MAC), the ability for more than one mobile to share the same timeslot (multi-user packets) and the introduction of QoS flags. All of these were put in place to allow for low latency, low bit rate communications such as VoIP.

In the United States, Verizon Wireless and Sprint Nextel have migrated 100% of their EV-DO Rev.0 networks to EV-DO Rev. A.

The additional forward rates for EV-DO Rev. A are:

DRC Index	Data rate in kbit/s	Slots scheduled	Payload size (bits)	Code Rate	Modulation
13	1536	2	5120	12-May	16-QAM
14	3072	1	5120	6-May	16-QAM

In addition to the changes on the forward link, the reverse link was enhanced to support higher complexity modulation (and thus higher bit rates). An optional secondary pilot was added, which is activated by the mobile when it tries to achieve enhanced data rates. To combat reverse link congestion and noise rise, the protocol calls for each mobile to be given an interference allowance which is replenished by the network when the reverse link conditions allow it. The reverse link has a maximum rate of 1.8 Mbit/s, but under normal conditions users experience a rate of approximately 500-1000kbit/s but with more latency than cable and dsl.

TIA-856 Rev. B

EV-DO Rev. B is a multi-carrier evolution of the Rev. A specification. It maintains the capabilities of EV-DO Rev. A, and provides the following enhancements:

Higher rates per carrier (up to 4.9 Mbit/s on the downlink per carrier). Typical deployments are expected to include 2 or 3 carriers for a peak rate of 14.7 Mbit/s. Higher rates by bundling multiple channels together enhance the user experience and enables new services such as high definition video streaming.
Reduced latency by using statistical multiplexing across channels -enhances the experience for latency sensitive services such as gaming, video telephony, remote console sessions and web browsing.
Increased talk-time and standby time
Reduced interference from the adjacent sectors especially to users at the edge of the cell signal which improves the rates that can be offered by using Hybrid frequency re-use.
Efficient support for services that have asymmetric download and upload requirements (i.e. different data rates required in each direction) such as file transfers, web browsing, and broadband multimedia content delivery.


TIA-1121

Ultra Mobile Broadband (UMB) was proposed by Qualcomm as the natural evolution path for CDMA2000, however, after most CDMA carriers chose to adopt the competing 3GPP Long Term Evolution (LTE) standard, development on UMB was cancelled in November 2008. Qualcomm is now backing the LTE standard.

Potential competing standards

Motorola proposed a new system called 1Xtreme as an evolution of CDMA2000, but it was rejected by the 3GPP2 standardization body. Later, a competing standard called EV-DV developed by Qualcomm, Lucent, Nokia, Motorola, etc. in 3GPP2 was proposed as an alternate evolution of CDMA. EV-DV stands for Evolution-Data and Voice, since the channel structure was backwards compatible with IS-95 and IS-2000 (1xRTT), allowing an in-band network deployment. In comparison, EV-DO requires 1 or more (1.25 MHz) freq. bands in addition to the voice band. (EV-DO Rev. A could potentially support a VoIP overlay network for voice calling, but this has not been pursued except for PTT, see QChat).

At the time, there was much debate on the relative merits of DV and DO. Traditional operators with an existing voice network preferred DV, since it does not require a separate band. Other design engineers, and newer operators without a 1x voice network, preferred EV-DO because it did not have to be backward compatible, and so could explore different pilot structures, reverse link silence periods, improved control channels, etc. And the network cost was lower, since EV-DO uses an IP network and does not require a SS7 network and complex network switches such as a mobile switching center (MSC). Also, equipment was not available for EV-DV in time to meet market demands whereas the EV-DO equipment and mobile application-specific integrated circuits (ASIC) were available and tested by the time the EV-DV standard was completed. As a result, the EV-DV standard was less attractive to operators, and has not been implemented. Verizon Wireless, then Sprint Nextel in 2004 and smaller operators in 2005 announced their plans to deploy EV-DO. In March 2005, Qualcomm suspended development of EV-DV chipsets, and focused on improving the EV-DO product line.


References

• http://www.engadgetmobile.com/2006/11/09/globalstar-gsp-1700-satphone-also-loaded-with-ev-do/
• http://www.cdg.org/technology/3g_1xEV-DO.asp
• http://web.archive.org/web/20061104082805/http://www.qualcomm.com/technology/1xev-do.html
• http://www.cdg.org/resources/white_papers/files/Lucent%201xEV-DO%20Rev%20O%20Mar%2004.pdf
• http://www.cdg.org/technology/3g/advantages_cdma2000.asp
• http://dx.doi.org/10.1109%2FWCNC.2007.601
• http://www.fiercewireless.com/press-releases/verizon-wireless-100-percent-wireless-broadband-network-now-enhanced-faster-speeds
• http://www.3gpp2.org/Public_html/specs/C.S0024-A_v2.0_050727.pdf
• http://en.wikipedia.org/wiki/3GPP2

External links

• http://www.3gpp2.org/
• http://www.cdg.org/
• http://www.evdoforums.com/
• http://mfile.akamai.com/8499/wmv/qualcomm.download.akamai.com/8499/1xEV/1x_EVDO_Rev_B_Demo.asx
• http://www.comsoc.org/ci1/Public/2006/feb/current.html

Source: www.wikipedia.org

W-CDMA (Wideband Code Division Multiple Access)

W-CDMA (Wideband Code Division Multiple Access), UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface found in 3G mobile telecommunications networks. It is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the UMTS family and sometimes used as a synonym for UMTS. It utilizes the DS-CDMA channel access method and the TDD duplexing method to achieve higher speeds and support more users compared to most time division multiple access (TDMA) schemes used today.

While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual-mode operation along with GSM/EDGE; a feat it shares with other members of the UMTS family.


Technical features

* Radio channels are 5MHz wide.
* Chip rate of 3.84 Mcps
* Supported mode of duplex: frequency division (FDD)
* Employs coherent detection on both the uplink and downlink based on the use of pilot symbols and channels.
* Supports inter-cell asynchronous operation.
* Variable mission on a 10 ms frame basis.
* Multicode transmission.
* Adaptive power control based on SIR (Signal-to-Interference Ratio).
* Multiuser detection and smart antennas can be used to increase capacity and coverage.
* Multiple types of handoff (or handover) between different cells including soft handoff, softer handoff and hard handoff.

Development

In the late 1990s, W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards, as an alternative to CDMA2000, EDGE, and the short range DECT system. Later, W-CDMA was selected as an air interface for UMTS.

As NTT DoCoMo did not wait for the finalisation of the 3G Release 99 specification, their network was initially incompatible with UMTS. However, this has been resolved by NTT DoCoMo updating their network.

Code Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by Qualcomm, the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones, its early IS-95 air interface standard. IS-95 evolved into the current CDMA2000 (IS-856/IS-2000) standard. Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA (3GPP) and CDMA2000 (3GPP2) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries as of 2006[update]. However, divergent requirements resulted in the W-CDMA standard being retained and deployed.

Despite incompatibilities with existing air-interface standards, the late introduction of this 3G system, and despite the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has been adopted and deployed rapidly, especially in Japan, Europe and Asia, and is already deployed in over 55 countries as of 2006[update].


Rationale for W-CDMA

W-CDMA transmits on a pair of 5 MHz-wide radio channels, while CDMA2000 transmits on one or several pairs of 1.25 MHz radio channels. Though W-CDMA does use a direct sequence CDMA transmission technique like CDMA2000, W-CDMA is not simply a wideband version of CDMA2000. The W-CDMA system is a new design by NTT DoCoMo, and it differs in many aspects from CDMA2000. From an engineering point of view, W-CDMA provides a different balance of trade-offs between cost, capacity, performance, and density; it also promises to achieve a benefit of reduced cost for video phone handsets. W-CDMA may also be better suited for deployment in the very dense cities of Europe and Asia. However, hurdles remain, and cross-licencing of patents between Qualcomm and W-CDMA vendors has not eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.

W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.

Deployment

The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in Japan in 2001.
Elsewhere, W-CDMA deployments are usually marketed under the UMTS brand. See the main UMTS article for more information.


References

• 3GPP notes that “there currently existed many different names for the same system (eg FOMA, W-CDMA, UMTS, etc) http://www.3gpp.org/ftp/op/OP_07/DOCS/pdf/OP6_13r1.pdf
• http://en.wikipedia.org/wiki/CPICH
• Hsiao-Hwa Chen (2007), John Wiley and Sons, pp. pp. 105–106, http://en.wikipedia.org/wiki/Special:BookSources/9780470022948
• http://www.gsmworld.com/news/press_2006/press06_44.shtml
• http://www.infoworld.com/article/07/04/05/HNqualcommonnokiapatents_1.html

External links

• http://www.3gpp.org/ftp/Specs/html-info/25-series.htm
• http://www.ericsson.com/technology/tech_articles/WCDMA.shtml
• http://www.qrctech.com/freq_chart_24x36.pdf

Source: www.wikipedia.org

Ultra-wideband (UWB)

Ultra-wideband (aka UWB, ultra-wide band, ultraband, etc.) is a radio technology that can be used at very low energy levels for short-range high-bandwidth communications by using a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precision locating and tracking applications.

UWB communications transmit in a way that doesn't interfere largely with other more traditional narrowband and continuous carrier wave uses in the same frequency band. However first studies show that the rise of noise level by a number of UWB transmitters puts a burden on existing communications services. This may be hard to bear for traditional systems designs and may affect the stability of such existing systems.


Overview

Ultra-Wideband (UWB) is a technology for transmitting information spread over a large bandwidth (>500 MHz) that should, in theory and under the right circumstances, be able to share spectrum with other users. Regulatory settings of FCC are intended to provide an efficient use of scarce radio bandwidth while enabling both high data rate "personal area network" (PAN) wireless connectivity and longer-range, low data rate applications as well as radar and imaging systems.

Ultra Wideband was traditionally accepted as pulse radio, but the FCC and ITU-R now define UWB in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% of the center frequency. Thus, pulse-based systems—wherein each transmitted pulse instantaneously occupies the UWB bandwidth, or an aggregation of at least 500 MHz worth of narrow band carriers, for example in orthogonal frequency-division multiplexing (OFDM) fashion—can gain access to the UWB spectrum under the rules. Pulse repetition rates may be either low or very high. Pulse-based UWB radars and imaging systems tend to use low repetition rates, typically in the range of 1 to 100 megapulses per second. On the other hand, communications systems favor high repetition rates, typically in the range of 1 to 2 giga-pulses per second, thus enabling short-range gigabit-per-second communications systems. Each pulse in a pulse-based UWB system occupies the entire UWB bandwidth, thus reaping the benefits of relative immunity to multipath fading (but not to intersymbol interference), unlike carrier-based systems that are subject to both deep fades and intersymbol interference.

Concept

A significant difference between traditional radio transmissions and UWB radio transmissions is that traditional systems transmit information by varying the power level, frequency, and/or phase of a sinusoidal wave. UWB transmissions transmit information by generating radio energy at specific time instants and occupying large bandwidth thus enabling a pulse-position or time-modulation. The information can also be imparted (modulated) on UWB signals (pulses) by encoding the polarity of the pulse, the amplitude of the pulse, and/or by using orthogonal pulses. UWB pulses can be sent sporadically at relatively low pulse rates to support time/position modulation, but can also be sent at rates up to the inverse of the UWB pulse bandwidth. Pulse-UWB systems have been demonstrated at channel pulse rates in excess of 1.3 giga-pulses per second using a continuous stream of UWB pulses (Continuous Pulse UWB or "C-UWB"), supporting forward error correction encoded data rates in excess of 675 Mbit/s. Such a pulse-based UWB method using bursts of pulses is the basis of the IEEE 802.15.4a draft standard and working group, which has proposed UWB as an alternative PHY layer.

One of the valuable aspects of UWB radio technology is the ability for a UWB radio system to determine "time of flight" of the direct path of the radio transmission between the transmitter and receiver at various frequencies. This helps to overcome multi path propagation, as at least some of the frequencies pass on radio line of sight. With a cooperative symmetric two-way metering technique distances can be measured to high resolution as well as to high accuracy by compensating for local clock drifts and stochastic inaccuracies.

Another valuable aspect of pulse-based UWB is that the pulses are very short in space (less than 60 cm for a 500 MHz wide pulse, less than 23 cm for a 1.3 GHz bandwidth pulse), so most signal reflections do not overlap the original pulse, and thus the traditional multipath fading of narrow band signals does not exist. However, there still is multipath propagation and inter-pulse interference for fast pulse systems which have to be mitigated by coding techniques.

Regulation

Ultra-Wideband (UWB) may be used to refer to any radio technology having bandwidth exceeding the lesser of 500 MHz or 20% of the arithmetic center frequency, according to Federal Communications Commission (FCC). A February 14, 2002 Report and Order by the FCC authorizes the unlicensed use of UWB in the range of 3.1 to 10.6 GHz. The FCC power spectral density emission limit for UWB emitters operating in the UWB band is -41.3 dBm/MHz. This is the same limit that applies to unintentional emitters in the UWB band, the so called Part 15 limit. However, the emission limit for UWB emitters can be significantly lower (as low as -75 dBm/MHz) in other segments of the spectrum.

Deliberations in the International Telecommunication Union Radiocommunication Sector (ITU-R) resulted in a Report and Recommendation on UWB in November 2005. National jurisdictions around the globe are expected to act on national regulations for UWB very soon. The UK regulator Ofcom announced a similar decision on 9 August 2007.

More than four dozen devices have been certified under the FCC UWB rules, the vast majority of which are radar, imaging or locating systems.

There has been much concern over the interference of narrow band signals and UWB signals that share the same spectrum; traditionally the only radio technology that operated using pulses was spark-gap transmitters, which were banned due to excessive interference. However, UWB is much lower power. The subject was extensively covered in the proceedings that led to the adoption of the FCC rules in the US, and also in the meetings relating to UWB of the ITU-R that led to the ITU-R Report and Recommendations on UWB technology. In particular, many common pieces of equipment emit impulsive noise (notably hair dryers) and the argument was successfully made that the noise floor would not be raised excessively by wider deployment of wideband transmitters of low power.


Theoretical discussion

One performance measure of a radio in applications like communication, locating, tracking, and radar, is the channel capacity for a given bandwidth and signaling format. Channel capacity is the theoretical maximum possible number of bits per second of information that can be conveyed through one or more links in an area. According to the Shannon–Hartley theorem, channel capacity of a properly encoded signal is proportional to the bandwidth of the channel and to the logarithm of signal-to-noise ratio (SNR)—assuming the noise is additive white Gaussian noise (AWGN). Thus channel capacity increases linearly by increasing bandwidth of the channel to the maximum value available, or equivalently in a fixed channel bandwidth by increasing the signal power exponentially. By virtue of the huge bandwidths inherent to UWB systems, huge channel capacities could be achieved in principle (given sufficient SNR) without invoking higher order modulations that need very high SNR to operate.

Ideally, the receiver signal detector should match with the transmitted signal in bandwidth, signal shape and time. Any mismatch results in loss of margin for the UWB radio link.

Channelization (sharing the channel with other links) is a complex problem subject to many practical variables. Typically two UWB links can share the same spectrum by using orthogonal time-hopping codes for pulse-position (time-modulated) systems, or orthogonal pulses and orthogonal codes for fast-pulse based systems.

Current forward error correction technology, as demonstrated recently in some very high data rate UWB pulsed systems (like Low density parity check code) can — perhaps in combination with Reed–Solomon error correction — provide channel performance very closely approaching the Shannon limit (See Shannon–Hartley theorem). When stealth is required, some UWB formats (mainly pulse-based) can fairly easily be made to look like nothing more than a slight rise in background noise to any receiver that is unaware of the signal’s complex pattern.

Multipath (distortion of a signal because it takes many different paths to the receiver) is an enemy of narrow-band radio. It causes fading where wave interference is destructive. Some UWB systems use "rake" receiver techniques to recover multi path generated copies of the original pulse to improve performance of the receiver. Other UWB systems use channel equalization techniques to achieve the same purpose. Narrow band receivers can use similar techniques, but are limited due to the poorer resolution capabilities of narrow band systems.

Multiple antenna technologies
Distributed MIMO: To increase the transmission range, this scheme exploits distributed antennas among different nodes.
Multiple antenna: Multiple antenna schemes such as MIMO have been used to increase the system throughput and the reception reliability. Since UWB has almost impulse-like channel response, the combination with multiple antenna techniques is preferable as well. Coupling MIMO spatial multiplexing with UWB's already high throughput gives the possibility of short-range networks with multi-gigabit rates.


Applications

Due to the extremely low emission levels currently allowed by regulatory agencies, UWB systems tend to be short-range and indoors applications. However, due to the short duration of the UWB pulses, it is easier to engineer extremely high data rates, and data rate can be readily traded for range by simply aggregating pulse energy per data bit using either simple integration or by coding techniques. Conventional OFDM technology can also be used subject to the minimum bandwidth requirement of the regulations. High data rate UWB can enable wireless monitors, the efficient transfer of data from digital camcorders, wireless printing of digital pictures from a camera without the need for an intervening personal computer, and the transfer of files among cell phone handsets and other handheld devices like personal digital audio and video players.

UWB is used as a part of location systems and real time location systems. The precision capabilities combined with the very low power makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare. Another benefit of UWB is the short broadcast time which enables implementers of the technology to install orders of magnitude more transmitter tags in an environment relative to competitive technologies. U.S.-based Parco Merged Media Corporation was the first systems developer to deploy a commercial version of this system in a Washington, DC hospital.

UWB is also used in "see-through-the-wall" precision radar imaging technology, precision locating and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. It exhibits excellent efficiency with a spatial capacity of approximately 1013 bit/s/m².

UWB has been a proposed technology for use in personal area networks and appeared in the IEEE 802.15.3a draft PAN standard. However, after several years of deadlock, the IEEE 802.15.3a task group was dissolved in 2006. Slow progress in UWB standards development, high cost of initial implementations and performance significantly lower than initially expected are some of the reasons for the limited success of UWB in consumer products, which caused several UWB vendors to cease operations during 2008 and 2009.

References

• http://www.wirelessnetdesignline.com/206800520;jsessionid=YNKESA1HKXHGYQSNDLQSKHSCJUNN2JVN?printableArticle=true
• http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-02-48A1.pdf
• http://www.ofcom.org.uk/consult/condocs/uwb_exemption/statement/statement.pdf
• http://www.ecti.or.th/%7Eexplorers/EEC/0602/Content_UWB78-84.pdf
• http://www.ieee802.org/15/pub/TG3a.html
• http://standards.ieee.org/board/nes/projects/802-15-3a.pdf
• http://venturebeat.com/2009/02/12/tzero-technologies-shuts-down-thats-the-end-of-ultrawideband/

Resources

• http://wcsp.eng.usf.edu/UWB_links.html
• http://ultra.usc.edu/

Source: www.wikipedia.org

Mobile VoIP

Mobile VoIP is an extension of mobility to a VoIP Voice over IP network.

There are several methodologies by which a mobile handset can be integrated into a VoIP network. One implementation turns the mobile device into a standard SIP client, which then uses a data network to send and receive SIP messaging, and to send and receive RTP for the voice path. This methodology of turning a mobile handset into a standard SIP client requires that the mobile handset support, at minimum, high speed IP communications. In this application, standard VoIP protocols (typically SIP) are used over any broadband IP-capable wireless network connection such as EVDO rev A (which is symmetrical high speed — both high speed up and down), HSDPA, WiFi or WiMAX.

Another implementation of mobile integration uses a softswitch like gateway to bridge SIP and RTP into the mobile network's SS7 infrastructure. In this implementation, the mobile handset continues to operate as it always has (as a GSM or CDMA based device), but now it can be controlled by a SIP application server which can now provide advanced SIP based services to it. Several vendors offer this kind of capability today.

Mobile VoIP will require a compromise between economy and mobility. For example, Voice over Wi-Fi offers potentially free service but is only available within the coverage area of a Wi-Fi Access Point. High speed services from mobile operators using EVDO rev A or HSDPA may have better audio quality and capabilities for metropolitan-wide coverage including fast handoffs among mobile base stations, yet it will cost more than the typical Wi-Fi-based VoIP service.

Mobile VoIP will become an important service in the coming years as device manufacturers exploit more powerful processors and less costly memory to meet user needs for ever-more 'power in their pocket'. Smartphones in mid-2006 are capable of sending and receiving email, browsing the web (albeit at low rates) and in some cases allowing a user to watch TV.

The challenge for the mobile operator industry is to deliver the benefits and innovations of IP without losing control of the network service. Users like the Internet to be free and high speed without extra charges for visiting specific sites. Such a service challenges the most valuable service in the telecommunications industry — voice — and threatens to change the nature of the global communications industry.


Technologies

Mobile VoIP relies on two main technologies:

* UMA — the Unlicensed Mobile Access Generic Access Network, designed to allow VoIP to run over the GSM cellular backbone
* SIP — the standard used by most VoIP services, and now being implemented on mobile handsets


Recent developments

In the summer of 2006, a SIP (Session Initiation Protocol) stack was introduced and a VoIP client in Nokia E-series dual-mode Wi-Fi handsets (Nokia E60, Nokia E61, Nokia E70). The SIP stack and client have since been introduced in many more E and N-series dual-mode Wi-Fi handsets, most notably the Nokia N95 which has been very popular in Europe. Various services use these handsets. Recently Nokia introduced a built in VoIP client to the mass market device (Nokia 6300i) running Series 40 operating system. Nokia maintains a list of all phones that have an integrated VoIP client here.

Aircell's battle with some companies allowing VoIP calls on flights is another example of the growing conflict of interest between incumbent operators and new VoIP operators.


References

• http://gigaom.com/2008/08/26/aircell-on-us-planes-voip-will-be-muted

External links

• http://opinion.zdnet.co.uk/comment/0,1000002138,39285315,00.htm

Source: www.wikipedia.org

W-CDMA_(UMTS)

W-CDMA (Wideband Code Division Multiple Access), UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface found in 3G mobile telecommunications networks. It is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the UMTS family and sometimes used as a synonym for UMTS. It utilizes the DS-CDMA channel access method and the TDD duplexing method to achieve higher speeds and support more users compared to most time division multiple access (TDMA) schemes used today.

While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual-mode operation along with GSM/EDGE; a feat it shares with other members of the UMTS family.


Technical features

* Radio channels are 5MHz wide.
* Chip rate of 3.84 Mcps
* Supported mode of duplex: frequency division (FDD)
* Employs coherent detection on both the uplink and downlink based on the use of pilot symbols and channels.
* Supports inter-cell asynchronous operation.
* Variable mission on a 10 ms frame basis.
* Multicode transmission.
* Adaptive power control based on SIR (Signal-to-Interference Ratio).
* Multiuser detection and smart antennas can be used to increase capacity and coverage.
* Multiple types of handoff (or handover) between different cells including soft handoff, softer handoff and hard handoff.

Development

In the late 1990s, W-CDMA was developed by NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT DoCoMo submitted the specification to the International Telecommunication Union (ITU) as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards, as an alternative to CDMA2000, EDGE, and the short range DECT system. Later, W-CDMA was selected as an air interface for UMTS.

As NTT DoCoMo did not wait for the finalisation of the 3G Release 99 specification, their network was initially incompatible with UMTS. However, this has been resolved by NTT DoCoMo updating their network.

Code Division Multiple Access communication networks have been developed by a number of companies over the years, but development of cell-phone networks based on CDMA (prior to W-CDMA) was dominated by Qualcomm, the first company to succeed in developing a practical and cost-effective CDMA implementation for consumer cell phones, its early IS-95 air interface standard. IS-95 evolved into the current CDMA2000 (IS-856/IS-2000) standard. Qualcomm created an experimental wideband CDMA system called CDMA2000 3x which unified the W-CDMA (3GPP) and CDMA2000 (3GPP2) network technologies into a single design for a worldwide standard air interface. Compatibility with CDMA2000 would have beneficially enabled roaming on existing networks beyond Japan, since Qualcomm CDMA2000 networks are widely deployed, especially in the Americas, with coverage in 58 countries as of 2006[update]. However, divergent requirements resulted in the W-CDMA standard being retained and deployed.

Despite incompatibilities with existing air-interface standards, the late introduction of this 3G system, and despite the high upgrade cost of deploying an all-new transmitter technology, W-CDMA has been adopted and deployed rapidly, especially in Japan, Europe and Asia, and is already deployed in over 55 countries as of 2006[update].


Rationale for W-CDMA

W-CDMA transmits on a pair of 5 MHz-wide radio channels, while CDMA2000 transmits on one or several pairs of 1.25 MHz radio channels. Though W-CDMA does use a direct sequence CDMA transmission technique like CDMA2000, W-CDMA is not simply a wideband version of CDMA2000. The W-CDMA system is a new design by NTT DoCoMo, and it differs in many aspects from CDMA2000. From an engineering point of view, W-CDMA provides a different balance of trade-offs between cost, capacity, performance, and density; it also promises to achieve a benefit of reduced cost for video phone handsets. W-CDMA may also be better suited for deployment in the very dense cities of Europe and Asia. However, hurdles remain, and cross-licencing of patents between Qualcomm and W-CDMA vendors has not eliminated possible patent issues due to the features of W-CDMA which remain covered by Qualcomm patents.

W-CDMA has been developed into a complete set of specifications, a detailed protocol that defines how a mobile phone communicates with the tower, how signals are modulated, how datagrams are structured, and system interfaces are specified allowing free competition on technology elements.

Deployment

The world's first commercial W-CDMA service, FOMA, was launched by NTT DoCoMo in Japan in 2001.
Elsewhere, W-CDMA deployments are usually marketed under the UMTS brand. See the main UMTS article for more information.


References

• 3GPP notes that “there currently existed many different names for the same system (eg FOMA, W-CDMA, UMTS, etc) http://www.3gpp.org/ftp/op/OP_07/DOCS/pdf/OP6_13r1.pdf
• http://en.wikipedia.org/wiki/CPICH
• Hsiao-Hwa Chen (2007), John Wiley and Sons, pp. pp. 105–106, http://en.wikipedia.org/wiki/Special:BookSources/9780470022948
• http://www.gsmworld.com/news/press_2006/press06_44.shtml
• http://www.infoworld.com/article/07/04/05/HNqualcommonnokiapatents_1.html

External links

• http://www.3gpp.org/ftp/Specs/html-info/25-series.htm
• http://www.ericsson.com/technology/tech_articles/WCDMA.shtml
• http://www.qrctech.com/freq_chart_24x36.pdf

Source: www.wikipedia.org

Universal Plug and Play (UPnP)

Universal Plug and Play (UPnP) is a set of networking protocols promulgated by the UPnP Forum. The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home (data sharing, communications, and entertainment) and in corporate environments for simplified installation of computer components. UPnP achieves this by defining and publishing UPnP device control protocols built upon open, Internet-based communication standards.

The term UPnP is derived from plug-and-play, a technology for dynamically attaching devices directly to a computer, although UPnP is not directly related to the earlier plug-and-play technology. UPnP devices are "plug-and-play" in that when connected to a network they automatically announce their network address and supported device and services types, enabling clients that recognize those types to immediately begin using the device.


Overview

The UPnP architecture allows peer-to-peer networking of PCs, networked home appliances, CE devices and wireless devices. It is a distributed, open architecture protocol based on established standards such as TCP/IP, UDP, HTTP, XML, and SOAP.

The UPnP architecture supports zero-configuration networking. A UPnP compatible device from any vendor can dynamically join a network, obtain an IP address, announce its name, convey its capabilities upon request, and learn about the presence and capabilities of other devices. DHCP and DNS servers are optional and are only used if they are available on the network. Devices can leave the network automatically without leaving any unwanted state information behind.

UPnP was published as a 73-part International Standard, ISO/IEC 29341, in December, 2008.

Other UPnP features include:

Media and device independence
UPnP technology can run on many media that support IP including Ethernet, FireWire, IR (IrDA), home wiring (G.hn) and RF (Bluetooth, Wi-Fi). No special device driver support is necessary; common protocols are used instead.
User interface (UI) Control
UPnP architecture enables devices to present a user interface through a web browser (see Presentation below).
Operating system and programming language independence
Any operating system and any programming language can be used to build UPnP products. UPnP does not specify or constrain the design of an API for applications running on control points; OS vendors may create APIs that suit their customer's needs.
Programmatic control
UPnP architecture also enables conventional application programmatic control.
Extensibility
Each UPnP product can have device-specific services layered on top of the basic architecture. In addition to combining services defined by UPnP Forum in various ways, vendors can define their own device and service types, and can extend standard devices and services with vendor-defined actions, state variables, data structure elements, and variable values.


Protocol

Addressing

The foundation for UPnP networking is IP addressing. Each device must have a Dynamic Host Configuration Protocol (DHCP) client and search for a DHCP server when the device is first connected to the network. If no DHCP server is available, that is, the network is unmanaged, the device must assign itself an address. The process by which a UPnP device assigns itself an address is known within the UPnP Device Architecture as "AutoIP". In UPnP Device Architecture Version 1.0, AutoIP is defined within the specification itself; in UPnP Device Architecture Version 1.1, AutoIP references IETF RFC 3927. If during the DHCP transaction, the device obtains a domain name, for example, through a DNS server or via DNS forwarding, the device should use that name in subsequent network operations; otherwise, the device should use its IP address.

Discovery

Given an IP address, the first step in UPnP networking is Discovery. The UPnP discovery protocol, defined in Section 1 of the UPnP Device Architecture, is known as the Simple Service Discovery Protocol (SSDP). When a device is added to the network, SSDP allows that device to advertise its services to control points on the network. Similarly, when a control point is added to the network, SSDP allows that control point to search for devices of interest on the network. The fundamental exchange in both cases is a discovery message containing a few, essential specifics about the device or one of its services, for example, its type, identifier, and a pointer to more detailed information.

Description

After a control point has discovered a device, the control point still knows very little about the device. For the control point to learn more about the device and its capabilities, or to interact with the device, the control point must retrieve the device's description from the URL provided by the device in the discovery message. The UPnP description for a device is expressed in XML and includes vendor-specific, manufacturer information like the model name and number, serial number, manufacturer name, URLs to vendor-specific web sites, etc. The description also includes a list of any embedded devices or services, as well as URLs for control, eventing, and presentation. For each service, the description includes a list of the commands, or actions, to which the service responds, and parameters, or arguments, for each action; the description for a service also includes a list of variables; these variables model the state of the service at run time, and are described in terms of their data type, range, and event characteristics.

Control

Having retrieved a description of the device, the control point can send actions to a device's service. To do this, a control point sends a suitable control message to the control URL for the service (provided in the device description). Control messages are also expressed in XML using the Simple Object Access Protocol (SOAP). Much like function calls, the service returns any action-specific values in response to the control message. The effects of the action, if any, are modeled by changes in the variables that describe the run-time state of the service.

Event notification

The next step in UPnP networking is event notification, or "eventing". The event notification protocol defined in the UPnP Device Architecture is known as GENA, an acronym for "General Event Notification Architecture". A UPnP description for a service includes a list of actions the service responds to and a list of variables that model the state of the service at run time. The service publishes updates when these variables change, and a control point may subscribe to receive this information. The service publishes updates by sending event messages. Event messages contain the names of one or more state variables and the current value of those variables. These messages are also expressed in XML. A special initial event message is sent when a control point first subscribes; this event message contains the names and values for all evented variables and allows the subscriber to initialize its model of the state of the service. To support scenarios with multiple control points, eventing is designed to keep all control points equally informed about the effects of any action. Therefore, all subscribers are sent all event messages, subscribers receive event messages for all "evented" variables that have changed, and event messages are sent no matter why the state variable changed (either in response to a requested action or because the state the service is modeling changed).


UPnP AV standards

UPnP AV stands for UPnP Audio and Video. On 12 July 2006 the UPnP Forum announced the release of version 2 of the UPnP Audio and Video specifications (UPnP AV v2), with new MediaServer version 2.0 and MediaRenderer version 2.0 classes. These enhancements are created by adding capabilities to the UPnP AV MediaServer and MediaRenderer device classes that allow a higher level of interoperability between MediaServers and MediaRenderers from different manufacturers. Some of the early devices complying with these standards were marketed by Philips under the Streamium brand name.

The UPnP AV standards have been referenced in specifications published by other organizations including Digital Living Network Alliance Networked Device Interoperability Guidelines, International Electrotechnical Commission IEC 62481-1, and Cable Television Laboratories OpenCable Home Networking Protocol.

UPnP AV components

* UPnP MediaServer DCP - which is the UPnP-server (a 'master' device) that shares/streams media-data (like audio/video/picture/files) to UPnP-clients on the network.
* UPnP MediaServer ControlPoint - which is the UPnP-client (a 'slave' device) that can auto-detect UPnP-servers on the network to browse and stream media/data-files from them.
* UPnP MediaRenderer DCP - which is a 'slave' device that can render content.
* UPnP RenderingControl DCP - control MediaRenderer settings; volume, brightness, RGB, sharpness, and more).
* UPnP Remote User Interface (RUI) client/server - which sends/receives control-commands between the UPnP-client and UPnP-server over network, (like record, schedule, play, pause, stop, etc.).

Web4CE (CEA 2014) for UPnP Remote UI - CEA-2014 standard designed by Consumer Electronics Association's R7 Home Network Committee. Web-based Protocol and Framework for Remote User Interface on UPnP Networks and the Internet (Web4CE). This standard allows a UPnP-capable home network device to provide its interface (display and control options) as a web page to display on any other device connected to the home network. That means that you can control a home networking device through any web-browser-based communications method for CE devices on a UPnP home network using ethernet and a special version of HTML called CE-HTML.

QoS (Quality of Service) - is an important (but not mandatory) service function for use with UPnP AV (Audio and Video). QoS (Quality of Service) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program. Since UPnP AV is mostly to deliver streaming media that is often near real-time or real-time audio/video data which it is critical to be delivered within a specific time or the stream is interrupted. QoS (Quality of Service) guarantees are especially important if the network capacity is limited, for example public networks, like the internet.

QoS (Quality of Service) for UPnP consist of Sink Device (client-side/front-end) and Source Device (server-side/back-end) service functions. With classes such as; Traffic Class that indicates the kind of traffic in the traffic stream, (for example, audio or video). Traffic Identifier (TID) which identifies data packets as belonging to a unique traffic stream. Traffic Specification (TSPEC) which contains a set of parameters that define the characteristics of the traffic stream, (for example operating requirement and scheduling). Traffic Stream (TS) which is a unidirectional flow of data that originates at a source device and terminates at one or more sink device(s).


NAT traversal

One solution for NAT (Network Address Translation) traversal, called the Internet Gateway Device (IGD) Protocol, is implemented via UPnP. Many routers and firewalls expose themselves as Internet Gateway Devices, allowing any local UPnP controller to perform a variety of actions, including retrieving the external IP address of the device, enumerate existing port mappings, and adding and removing port mappings. By adding a port mapping, a UPnP controller behind the IGD can enable traversal of the IGD from an external address to an internal client.

Problems with UPnP


Lack of Default Authentication

The UPnP protocol, as default, does not implement any authentication, so UPnP device implementations must implement their own authentication mechanisms, or implement the Device Security Service. There also exists a non-standard solution called UPnP-UP (Universal Plug and Play - User Profile) which proposes an extension to allow user authentication and authorization mechanisms for UPnP devices and applications.

Unfortunately, many UPnP device implementations lack authentication mechanisms, and by default assume local systems and their users are completely trustworthy.

Most notably, routers and firewalls running the UPnP IGD protocol are vulnerable to attack since the framers of the IGD implementation omitted a standard authentication method. For example, Adobe Flash programs are capable of generating a specific type of HTTP request. This allows a router implementing the UPnP IGD protocol to be controlled by a malicious web site when someone with a UPnP-enabled router simply visits that web site. The following changes can be made silently by code embedded in an Adobe Flash object hosted on a malicious website:

* Port forward internal services (ports) to the router external facing side (i.e. expose computers behind a firewall to the Internet).
* Port forward the router's web administration interface to the external facing side.
* Port forwarding to any external server located on the Internet, effectively allowing an attacker to attack an Internet host via the router, while hiding their IP address.
* Change DNS server settings so that when victims believe they are visiting a particular site (such as an on-line bank), they are redirected to a malicious website instead.
* Change the DNS server settings so that when a victim receives any software updates (from a source that isn't properly verified via some other mechanism, such as a checking a digital certificate has been signed by a trusted source), they download malicious code instead.
* Change administrative credentials to the router/firewall.
* Change PPP settings.
* Change IP settings for all interfaces.
* Change WiFi settings.
* Terminate connections.

This only applies to the "firewall-hole-punching"-feature of UPnP; it does not apply when the IGD does not support UPnP or UPnP has been disabled on the IGD. Also, not all routers can have such things as DNS server settings altered by UPnP because much of the specification (including LAN Host Configuration) is optional for UPnP enabled routers

Other Issues

UPnP uses HTTP over UDP (known as HTTPU and HTTPMU for unicast and multicast), even though this is not standardized and is specified only in an Internet-Draft that expired in 2001.
UPnP does not have a lightweight authentication protocol, while the available security protocols are complex. As a result, some UPnP devices ship with UPnP turned off by default as a security measure.


Future developments

The standard DPWS is a candidate successor for UPnP. It solves many of the problems of UPnP. A DPWS client is included in Microsoft Windows Vista as part of the Windows Rally technologies.

Another alternative, NAT-PMP, is an IETF draft introduced by Apple Inc. in 2005.

UPnP 1.1 has in fall 2008 been ratified by the UPnP forum as successor for UPnP 1.0.


References

• http://www.iec.ch/news_centre/release/nr2008/nr4008.html
• http://www.iso.org/iso/pressrelease.htm?refid=Ref1185
• http://www.upnp.org/news/documents/UPnPForum_02052009.pdf
• http://www.upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v1.0.pdf
• http://www.upnp.org/specs/arch/UPnP-arch-DeviceArchitecture-v1.1.pdf
• http://www.ietf.org/rfc/rfc3927.txt
• http://www.dlna.org/industry/certification/guidelines
• http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=E&wwwprog=cat-det.p&progdb=db1&wartnum=038283
• http://www.cablelabs.com/specifications/OC-SP-HNP-I01-060630.pdf
• http://www.ce.org/Standards/browseByCommittee_2757.asp
• http://www.upnp.org/standardizeddcps/security.asp
• http://www.upnp-up.org/
• http://www.shorewall.net/UPnP.html
• http://linux-igd.sourceforge.net/documentation.php#SECURITY
• http://www.gnucitizen.org/blog/hacking-the-interwebs
• http://www.gnucitizen.org/blog/flash-upnp-attack-faq
• http://www.upnp.org/standardizeddcps/igd.asp
• http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/30/30482/01405701.pdf?temp=x

Books

* Golden G. Richard: Service and Device Discovery : Protocols and Programming, McGraw-Hill Professional, ISBN 0-07-137959-2
* Michael Jeronimo, Jack Weast: UPnP Design by Example: A Software Developer's Guide to Universal Plug and Play, Intel Press, ISBN 0-9717861-1-9


External links

• http://upnp.org/standardizeddcps/default.asp
• http://www.upnp-database.info/ Community-based database of UPnP/AV Devices.

Source: www.wikipedia.org