HASMUKH GOSWAMI COLLEGE OF ENGINEERING VAHELAL, AHMEDABAD.

Year:2010

Certificate

This is to certify that the seminar entitled “CRYPTOGRAPHY” and submiitted by SALONI BHARGAVA having roll no 02 for the partial fullfilment of requirements of Bachelor of Engineering(Information Technology) degree of HASMUKH GOSWAMI COLLEGE OF ENGINEERING, VAHELAL, AHMEDABAD, Gujarat, India embodies

the bonafied work done by haer under my supervision.

Name of guide:

Miss Ankita Patel

Place:

Date :

HASMUKH GOSWAMI COLLEGE OF ENGINEERING Vahelal,Ahmedabad.

Year:2010

Acknowledgement

I would like to take this opportunity to thank my teacher and guide Miss Ankita patel for her

advice and continued support without which it would not have been possible to complete this

report.

I would also like to thank entire computer department and faculty for helping me in every

possible manner during this course.

ABSTRACT

Wireless USB is a short-range, high-bandwidth wireless radio communication protocol created by the Wireless USB Promoter Group. Wireless USB is sometimes abbreviated as "WUSB", although the USB Implementers Forum discourages this practice and instead prefers to call the technology "Certified Wireless USB" to differentiate it from competitors. Wireless USB is based on the WiMedia Alliance’s Ultra-Wideband (UWB) common radio platform, which is capable of sending 480 Mbit/s at distances up to 3 meters and 110 Mbit/s at up to 10 meters. It was designed to operate in the 3.1 to 10.6 GHz frequency range, although local regulatory policies may restrict the legal operating range for any given country.

The Wireless USB Promoter Group was formed in February 2004 to define the Wireless USB specifications. In May 2005, the Wireless USB Promoter Group announced the completion of the Wireless USB specification.

WUSB performance at launch will provide adequate bandwidth to meet the requirements of a typical user experience with wired connections. The 480 Mbps initial target bandwidth of WUSB is comparable to the current wired USB 2.0 standard. With 480 Mbps being the initial target, WUSB specifications will allow for generation steps of data throughput as the ultra wideband radio evolves and with future process technologies, exceeding limits of 1 Gbps.

The specification is intended for WUSB to operate as a wire replacement with targeted usage models for cluster connectivity to the host and device-to-device connectivity at less than 10 meters. The interface will support quality delivery of rich digital multimedia formats, including audio and video, and will be capable of high rate streaming (isochronous transfers).

Wireless USB is used in game controllers, printers, scanners, digital cameras, MP3 players, hard disks and flash drives. Kensington released a Wireless USB universal docking station in August, 2008. It is also suitable for transferring parallel video streams, while utilizing the Wireless USB over UWB bandwidth.

The WUSB architecture allows up to 127 devices to connect directly to a host. Because there are no wires or ports, there is no longer a need for hubs. WUSB host capability can be added to existing PCs through the use of a Host Wire Adapter (HWA).WUSB performance at launch will provide adequate bandwidth to meet the requirements of a typical user experience with wired connections.

The main disadvantage of wireless USB that it has no major drivers for W-USB.

INDEX

No TOPIC Page no

1. Introduction 6

2. Development of wireless USB 6

3. Whai is wireless USB 7

4. WUSB topology 8

5. Applications 8

6. Security and Device association 15

7. Future developments 16

8. Security Architecture 19

9. Applications 19

10. Examples 26

11. Future developments 22

12. Conclusion 23

13. Bibliography 23

1. INTRODUCTION Imagine if all the devices in a home office -- such as printer, scanner, external hard drive, and digital camera -- could be connected to your PC without any wires. Imagine if all the components for an entire home entertainment center could be set up and connected without a single wire. Imagine if digital pictures could be transferred to a photo print kiosk for instant printing without the need for a cable. These are just some of the possible scenarios for high-speed wireless USB (WUSB) connectivity, the latest technology developed to bring even greater convenience and mobility to devices.

Universal serial bus (USB) technology has been a popular connection type for PCs and it's migrating into consumer electronic (CE) and mobile devices. Now this high-speed and effective connection interface is unwiring to provide the functionality of wired USB without the burden of cables. This next iteration of USB technology is the focus of the new Wireless USB Promoter Group, which will define the specifications that will eventually provide standards for the technology.

2. DEVELOPMENT OF CRYPTOGRAPHY

The Wireless USB Promoter Group was formed in February 2004 to define the Wireless USB specification. The group consists of Agere Systems (now merged with LSI Corporation), Hewlett-Packard, Intel, Microsoft, NEC Corporation, Philips and Samsung.

In May 2005, the Wireless USB Promoter Group announced the completion of the Wireless USB specification.

In June 2006, five companies showed the first multi-vendor interoperability demonstration of Wireless USB. A laptop with an Intel host adapter using an Alereon PHY was used to transfer high definition video from a Philips wireless semiconductor solution with a Realtek PHY, all using Microsoft Windows XP drivers developed for Wireless USB.

In October 2006 the U.S. Federal Communications Commission (FCC) approved the first complete Host Wire Adapter (HWA) and Device Wire Adapter (DWA) wireless USB solution from WiQuest Communications for both outdoor and indoor use. The first retail product was shipped by IOGEAR using Alereon, Intel and NEC silicon in mid-2007. Around the same time, Belkin, Dell, Lenovo and D-Link began shipping products that incorporated WiQuest technology. These products included embedded cards in the notebook PCs or Hub/Adapter solutions for those PCs that do not currently include Wireless USB. In 2008, a new Wireless USB Docking Station from Kensington was made available through Dell. This product was unique as it was the first product on the market to support video and graphics over a USB connection, by using DisplayLink USB graphics technology. Kensington's Docking Station enables wireless connectivity between a notebook PC and an external monitor, speakers, and existing wired USB peripherals. Imation announced Q408 availability of a new external Wireless HDD. Both of these products are based on WiQuest technology.

On March 16, 2009, the WiMedia Alliance announced it is entering into technology transfer agreements for the WiMedia Ultra-wideband (UWB) specifications. WiMedia will transfer all current and future specifications, including work on future high speed and power optimized implementations, to the Bluetooth Special Interest Group (SIG), Wireless USB Promoter Group and the USB Implementers Forum. After the successful completion of the technology transfer, marketing and related administrative items, the WiMedia Alliance will cease operations.In October 2009 the Bluetooth Special Interest Group has dropped development of UWB as part of the alternative MAC/PHY, Bluetooth 3.0/High Speed solution. A small, but significant, number of former WiMedia members had not and would not sign up to the necessary agreements for the IP transfer. The Bluetooth group is now turning its attention from UWB to 60 GHz.

WHAT IS WIRELESS USB?

Wireless USB is a short-range, high-bandwidth wireless radio communication protocol created by the Wireless USB Promoter Group. Wireless USB is sometimes abbreviated as "WUSB", although the USB Implementers Forum discourages this practice and instead prefers to call the technology "Certified Wireless USB" to differentiate it from competitors. Wireless USB is based on the WiMedia Alliance's Ultra-WideBand (UWB) common radio platform, which is capable of sending 480 Mbit/s at distances up to 3 meters and 110 Mbit/s at up to 10 meters. It was designed to operate in the 3.1 to 10.6 GHz frequency range, although local regulatory policies may restrict the legal operating range for any given country.

Features of wireless USB technologyWireless USB will build on the success of Wired USB. An important goal of theWUSB Promoter Group is to ensure that wireless USB offers users the experiencethey have come to expect from wired USB. Toward that end, the Wireless USBstandard is being designed to support the following features.

Backward compatibility

Wireless USB will be fully backward compatible with the one billion wired USBconnections already in operation. Moreover, Wireless USB will be compatible withcurrent USB drivers and firmware and provide bridging from wired USB devices andhosts.

High performance

At launch, Wireless USB will provide speeds up to 480 Mbps, a performancecomparable to the wired USB 2.0 standard and high enough to provide wirelesstransfer of rich digital multimedia formats. As UWB technology and processtechnologies evolve, bandwidth may exceed 1 Gbps.

Simple, low-cost implementation

Implementation will follow the wired USB connectivity models as closely as possible

to reduce development time and preserve the low-cost, ease-of-use model that hasmade wired USB the interconnect of choice.An easy migration pathTo enable an easy migration path from wired USB, Wireless USB will maintain thesame usage models and architecture as wired USB

Reasons for Wireless USBThe wired USB is there to help with the PC connectivity problems. We already havmany wireless solutions also, like Wi-Fi, Bluetooth etc. In such a scenario why are wegoing for a new technology called Wireless USB. Two things account for this, one islack of easiness of use in wired USB the other one is inefficiency of current wirelesssolutions.Issues of wired USB

Wires are restrictive. Once plugged into a socket we cannot move thedevice around like what we can do with wireless or mobile devices.This restriction to free movement is a hindrance to the modern ideas ofmobile offices.

Multiple wires can be a hassle. No one likes t o see the multitude ofwires behind the PC, some times making knots with each other andcausing all sorts of trouble when we try to remove or reconfigure anycomponent. To remove all these problems with no loss at all is a goodidea, and Wireless USB does that.

In many situations wireless solutions can easily deliver same speedsthat wired solutions are delivering. So there is a good reason for a shiftto wireless solutions.Inadequacy of current wireless solutions• Bluetooth

Bandwidth of 3 Mbps is not enough for most of theapplications which needs very high bandwidth. Theapplications like video, HDTV, monitor etc. are goodexamples.• Wi-Fi

One of the main disadvantage of Wi-Fi is its high expense toset up a network and make it working. It is not always feasibleto install Wi-Fi for home or personal networks.o Another draw back of Wi-Fi is the higher power consumption.

Power consumption is one of the important hurdles of wirelessdesigners. As the wireless devices work on their own power,almost always battery power, the high power consumptionbecomes a big drawbackCompatibility options for older hardware

The WUSB architecture allows up to 127 devices to connect directly to a host. Because there are no wires or ports, there is no longer a need for hubs.

However, to facilitate the migration from wired to wireless, WUSB introduced a new Device Wire Adapter (DWA) class. Sometimes referred to as a "WUSB hub", a DWA allows existing USB 2.0 devices to be used wirelessly with a WUSB host.

WUSB host capability can be added to existing PCs through the use of a Host Wire Adapter (HWA). The HWA is a USB 2.0 device that attaches externally to a desktop or laptop's USB port or internally to a laptop's MiniCard interface.

WUSB also supports dual-role devices (DRDs), which in addition to being a WUSB device, can function as a host with limited capabilities. For example, a digital camera could act as a device when connected to a computer and as a host when transferring pictures directly to a printer.

Relation to ultra-wideband (UWB)

A common source of confusion is about the relationship between WUSB, WiMedia, and UWB. The UWB and WUSB technologies are not the same, and the terms WUSB and UWB are not synonymous.

UWB is a general term for a new type of radio communication using pulses of energy which spread emitted Radio Frequency energy over 500 MHz+ of spectrum or exceeding 20% fractional bandwidth within the frequency range of 3.1 GHz to 10.6 GHz as defined by the FCC ruling issued for UWB in Feb. 2002. UWB is NOT specific to WiMedia or any other company or group and there are in fact a number of groups and companies developing UWB technology totally unrelated to WiMedia. Some companies[which?] use UWB for ground penetrating radar, through wall radar and yet another company Pulse-LINK uses it as part of a whole home entertainment network using UWB for transmission over both wired and wireless media. WUSB is a protocol promulgated by the USB-IF that uses WiMedia's UWB radio platform. Other protocols that have announced their intention to use WiMedia's UWB radio platform include Bluetooth and the WiMedia Logical Link Control Protocol.

Comparing digital RF systems

Wireless USB vs. 802.11a/b/g & Bluetooth [4]

SpecificationWireless USB

Specification Rev. 1.0

Bluetooth 4.0 (proposed)

Wi-Fi (IEEE 802.11n)

Bluetooth 2.1 + EDR

Frequency band 3.1 GHz–10.6 GHz UWB (not decided) 2.4 GHz/5 GHz 2.4 GHz

Bandwidth 53 - 480 Mbit/s 53 - 480 Mbit/s Max. 600 Mbit/s Max. 3 Mbit/s

Distance 3 - 10 m unknown distance 100 m1 – 100 m,

depending on output

Modulation MB-OFDM MB-OFDMDSSS, DBPSK,

DQPSK,CCK, OFDM

GFSK

Standardization May 2005 pre-standard September 2009 July 2007

WUSB TOPOLOGY

The fundamental relationship in WUSB is a hub and spoke topology, as shown in Figure 1. In this topology, the host initiates all the data traffic among the devices connected to it, allotting time slots and data bandwidth to each device connected. These relationships are referred to as clusters. The connections are point-to-point and directed between the WUSB host and WUSB device.

Figure 1 -- WUSB topology

The WUSB host can logically connect to a maximum of 127 WUSB devices, considered an informal WUSB cluster. WUSB clusters coexist within an overlapping spatial environment with minimum interference, thus allowing a number of other WUSB clusters to be present within the same radio cell.

Topology will support a dual role model where a device can also support limited host capabilities. This model allows mobile devices to access services with a central host supporting the services (i.e., printers and viewers). This model also allows a device to access data outside an existing cluster it may currently be connected to by creating a second cluster as a limited host.

Additionally, high spatial capacity in small areas is needed to enable multiple device access to high bandwidth concurrently. Multiple channel activities may take place within a given area. The topology will support multiple clusters in the same area. The number of clusters to be supported is still being determined.

DESIGN CONSIDERATIONS

There are several architectural considerations in developing WUSB. In addition to providing wireless connectivity, WUSB must be backwards compatible with wired USB and provide a bridge to wired USB devices. Also, the host and solutions will need to enable the exchange of data between clusters or devices not related to the same host.

Low-cost implementation of WUSB will also be important to the successful integration of the technology. Implementation will follow the wired USB connectivity models as closely as

possible to reduce development time and to preserve the low-cost, easy-to-use model, which has become pervasive in the PC industry.

PERFORMANCEWUSB performance at launch will provide adequate bandwidth to meet the requirements of a typical user experience with wired connections. The 480 Mbps initial target bandwidth of WUSB is comparable to the current wired USB 2.0 standard. With 480 Mbps being the initial target, WUSB specifications will allow for generation steps of data throughput as the ultra wideband radio evolves and with future process technologies, exceeding limits of 1 Gbps.

The specification is intended for WUSB to operate as a wire replacement with targeted usage models for cluster connectivity to the host and device-to-device connectivity at less than 10 meters. The interface will support quality delivery of rich digital multimedia formats, including audio and video, and will be capable of high rate streaming (isochronous transfers).

Radio System Power and Power Management

Radio system power (power used only by the radio) will be expected to meet the most stringent requirements where mobile and handheld battery life is important. For example, typical PDAs use 250–400 mW without a radio connection, while typical cellular phones use 200 mW–300 mW with the primary WAN radio. Adding a WUSB radio should not increase power requirements any more than existing wireless technologies already employed today.

Battery-powered operation requires reasonable battery life: 2–5 days for highly mobile devices and several months for intermittently used devices like remote controls. WUSB, based on the MultiBand OFDM Alliance (MBOA) radio, will strive to meet these standards. The power target for WUSB radio will be introduced at less than 300 mW and drive to a target of 100 mW over time.

Dual-Role Devices

A new class of devices, called WUSB dual-role devices, will give rise to usage scenarios not previously possible. These devices will offer both limited host and device capabilities similar to USB On-The-Go.

Applications

With the growing use of digital media in the PC, consumer electronic (CE) and mobile communication environments, a common standard interconnect is needed to support the on-going convergence of these environments. The trend toward convenient wireless distribution of digital information provides an opportunity to introduce a single, standard wireless interconnect capable of supporting usage models across all three environments.

The CE environment will have high-performance wireless interface expectations. Consumer usage models (Figure 2) will center on streaming media distribution that typically uses

compression algorithms. The performance objective is to ensure a high quality of service is maintained to meet typical consumer entertainment expectations.

Figure 2 -- Consumer Usage Models

Typical video delivery with standard SDTV/DVD will consume between 3 and 7 Mbps while HDTV will use between 19 and 24 Mbps. A point distribution technology like wireless USB with an effective bandwidth of 480 Mbps could manage multiple HDTV streams. Host buffering could enable a network backbone to effectively distribute content to all distribution hosts, enhancing the quality experience for all users.

Business applications for WUSB include a variety of different usage possibilities. Common devices such as printers, scanners, hard drives, and projectors could all be used in wireless scenarios. These devices would function the same way as if they were using wired USB, but without all the cables. Office services on the corporate network could migrate to WUSB and benefit from faster performance than shared network devices offer.

Connectivity

USB can form true USB systems, formed by a host, devices and interconnection support. It implements the USB hub-spoke model, in which up to 127 wireless devices can form point-to-

point links (spokes) with the host (the hub). The host controller is unique in the system and is usually embedded in a working computer, though it could be connected to it through a simple USB connection, possibly wireless as well. Such a topology is similar to a star network (but all communications are strictly point-to-point, never between devices).

In order to allow common wired USB devices to be connected, the specification defines device wire adapters. Likewise, hosts connect to W-USB systems through use of a host wire adapter. Even though the physical layer is based on Ultra-WideBand, W-USB devices have a fully compliant USB interface. The physical layer may support a wide range of transfer rates, of which three are defined as mandatorily supported: 53.3, 106.7 and 200 Mbit/s, all other possible UWB rates being optional for devices (hosts must support them all).

W-USB devices are categorized in the same way as traditional USB. Because of the existence of wire adapters, traditional USB hubs are not needed. A device supports one or more communication pipes to the host, and allocates endpoint 0 for the USB control pipe. Device type information is available through this pipe.

Connections with the host are created by means of an establishment message sent at some point. Both host and device can then proceed to authenticate using their unique keys; if the process succeeds, the host assigns a unique USB address to the device, after which the device becomes visible to the USB protocol. Because the connectivity model allows for on-the-fly, unannounced disconnection, connections must always remain active. Aside from host- or device-forced disconnections, long inactivity periods may trigger the same termination mechanisms.

In addition, W-USB hosts have other responsibilities which go beyond those of a wired host; namely, their MAC sublayer is responsible for supervising the suitability of device MAC layers. If needed, this requires assisting them in their beaconing duties and processing the beaconing data that could be sent to them. Furthermore, the UWB radio and associated bandwidth may be shared with other entities, and the host must make sure that the defined policies are satisfied; according to shared use (which may be coordinated to avoid interference) it will be able to offer full or partial functionality.

Protocol architecture

The USB model is preserved, and generally minor adjustments made to fit the specific needs of a wireless system. The changes are as follows, from top to bottom:

The function layer only suffers minor changes to increase efficiency and support isochronism.

The device layer includes wireless-oriented security and device management features. The bus layer does not change its functionality, but is substantially adapted for efficiency

and security on wireless networks.

Changes to USB

It is interesting to note the main changes undergone by the bus layer: the replacement of copper wires introduces ambiguity in the actual state of host-device connections and, even more importantly, potentially exposes communications fully to any other device within the propagation range, whereas they were reasonably secure over the wire. Hence an explicit secure relationship must be established. For this, the bus and device layers incorporate the necessary resources for use by the function layer. Every W-USB transmission is encrypted by the bus layer without impairing layer-to-layer horizontal communication.

The bus follows a TDMA-based polling approach supervised by the host. A transfer is formed by three parts: token, data and handshake. For efficiency reasons, several tokens containing timing information for the devices can be grouped into one, thus forming transaction groups. Flow control and packet sizes are adjusted for power efficiency, while respecting the high-level pipe model of communication between source and destination.

Even preserving the USB model typical error rates in wireless media require modifications in the mechanisms used to achieve said model: among others, data handshakes and buffering.

Underlying protocol stack

UWB defines both PHY and MAC layers, which need to be integrated in the W-USB model. In particular, MAC is joined with the logical link control (LLC) sublayer to form the link layer, responsible for encryption/decryption, PHY error management and synchronization, while PHY itself covers the correctness of headers, not payloads.

The MAC layer is particularly relevant to W-USB. It uses superframes divided in 256 time slots, the first of which are dedicated to the transfer of beaconing information. Slots can further be allocated to meet the necessities of clusters of devices, also identified by MMC's (see below). A host maintains one or more W-USB communication channels and is fully aware of the MAC layer, whereas a device only needs to use the defined W-USB interface to communicate through existing channels.

There are three degrees of MAC consciousness in devices. The highest of these corresponds to a self-beaconing device, which is able to perform beaconing on its own. The following degree

represents directed-beaconing devices, which are unaware of MAC frames and have limited beaconing capabilities, depending on the host to detect and beacon for nearby devices. Lastly there are non-beaconing devices, which have a very limited ability to transmit and receive; on the other hand, devices which are undetectable by the host can not be affected by these devices, nor can affect them.

Thus, non-beaconing devices can only operate in very close vicinity to the host. Directed- and self-beaconing devices must be able to identify their hidden neighbors, which they do by emitting beacons. On their end, hosts manage global timers with the precision the physical medium requires (20 ppm). Channel time is sent within MMC's, and it is used for slot allocation, so it is important that hosts perform accurate beaconing. Devices may as well beacon reservation declarations.

The superframe includes device notification time slots for asynchronous transfers initiated by the devices (which do not use pipes, but instead tap the bus layer directly); the host dynamically assigns slots as needed. Besides these, W-USB transactions between the host and endpoints are carried out as in USB.

Data transport architecture

Transactions use TDMA microscheduling while adhering to USB semantics. A split-transaction protocol is used to allow multiple transactions to be carried out simultaneously. This is related to the transaction group concept, which consists of a microscheduled management command (MMC) and allocated time slots for the execution of its associated workload.

Wireless data transfers tend to incur in very significant overheads; to mitigate this W-USB replaces these with the burst mode data phase, which groups one or more data packets which reducing packet delimiters and separation gaps, in contrast with the USB rule of one data packet per transaction. The extent to which this practice is applied can be adjusted, resulting in a varying degree of equity between competing devices.

The specification defines four particular data transfer types; their identifying features are summarized here.

Bulk transfers tap the channel as bandwidth is available. Delivery is guaranteed, but neither transfer rate nor latency are, though the host can attempt to leverage pending transfers or endpoints. They are used for high-volume transfers exhibiting a sharp time-varying behavior. They use unidirectional pipes.

Interrupt transfers serve short transactions which demand high reliability and low latency. Maximum service period is guaranteed, as are a number of retries during said period.

Isochronous transfers provide guaranteed transfer rates and bounded latency for transmission attempts, as well as on-average constant data rate (although dependent on the medium, usually comparable to the rates achievable by wired USB). There is also at least one guaranteed retry during the service period, and it supports additional reliability against error bursts by adding delay to the stream according to buffering capacity;

payload sizes can be adjusted. Still, it may eventually be necessary to discard the oldest data in the buffers (the receiver can be informed of the amount of information discarded while the channel is not usable). Hosts will only discard data if the presentation time for a packet expires.

Control transfers are the same as in USB 2.0. The system uses a best-effort policy, but software may restrict channel access and available bandwidth for devices.

Power management can also affect data transport, since devices may control their power use at their discretion. The fact that the communications protocol is based on TDMA means that both host and devices know exactly when their presence is not required, and can use this to enter power saving modes. Devices may turn off their radios transparently to the host while maintaining their connections. They can also turn off over extended periods of time if they previously notify the host, as they will ignore all communications from said host. Eventually, the device will trigger the wakeup procedure and check for pending work.

In turn, the host will usually turn its radio off when it is not needed. If it decides to stop the channel, be in temporarily or to enter hibernation or shutdown states, it must notify the devices before it can do so.

Competitors

UWB

Other forms of USB over wireless exist, such as those based on the competing direct sequence UWB technology by Freescale (Cable-Free USB). The same is also true for other radio frequency based wire replacement systems which can carry USB. The result is that the name 'Certified Wireless USB' was adopted to allow consumers to identify which products would be adherent to the standard and would support the correct protocol and data rates.

Security and Device Association

WUSB security will ensure the same level of security as wired USB. Connection-level security between devices will ensure that the appropriate device is associated and authenticated before operation of the device is permitted. Higher levels of security involving encryption should be implemented at the application level. Processing overhead supporting security should not impose noticeable performance impacts or add device costs.

One of the primary objectives when implementing a wireless interconnect is that it is easy to install and use. Wired connections provide the user with implied expectations, that is that the device is connected as specified by the user when they install the wire. When the wire is installed, the user has basic expectations and when these expectations do not take place (plug does not fit), there is a known recourse.

Wireless connections, on the other hand, due to environmental characteristics, may establish connection paths that are not obvious. In fact, it may not be obvious when a device is connected.

So WUSB devices installed for the first time should automatically install drivers, security features, and so on and associate with systems that they can interact with. The concepts of 'turn on and use it' with an easy setup procedure will be employed.

Sample device connect

Fig: Sample device connect

Connection context

In order to make secure relationships consistent across multiple connections,some amount of context must be maintained by both device and host. In the caseof wireless USB. This connection context consists of three pieces of information.,a unique host ID (CHID), a unique device ID (CDID) and a symmetric key (CK)that is shared by both parties. The symmetric key is referred to in this document asthe connection key. This key is used to reestablish the connection at a later time.This key is always unique. The host never gives the same connection key tomultiple devices.

Fig: Connection context

A connection context must contain non zero CHID and CDID values to beuseable by the device. A host can use a CC with a value of zero in either field torevoke an existing context. When loading a context for conection purposes, if adevice discovers a CC that contain CHID or CCID values of zero , it shall treatthat CC as if it were entirely blank. The device shall make no use of the otherfields.Devices may find ways to add value by supporting multiple CCs . Each CCsupported by the device must contain a unique CHID. In the case a devicesupports multiple CCs only the CC used to connect the host shall be madeaccessible to the host.

Enabling products

It is useful to note in a discussion regarding Wireless USB is that the end goal of thesolution is to provide a cable replacement for a pure USB connection. Many WirelessUSB adapters exist today, but these adapters do not perform the function required of atrue Wireless USB solution.A USB adapter, devices such as USB-to-Serial, USB-to-Ethernet, USB-to-802.11and USB modems (USB-to-Telco or USB-to-Cable TV), provides an externalconnection and protocol conversion that just happens to connect to the PC via USB.The USB device itself is the dongle or adapter unit directly connected to the host. Theremote side is not a USB device, and the connection is not USB. The goal of a trueWirelesses solution is to enable connectivity of any USB device, and provide thesame convenience of a simple wired USB connection.

3.6.1 Device Wire Adapters

Device wire adapter looks like a simple USB hub. It consists of traditional USB Atype ports in it and USB devices can connet to it with the wired USB technology. TheDWA connects wirelessly to the HWA or the wireless host integrated into the hostmachine as PCI or PCI(e). Single chip implementations of DWA can be directlyintegrated into devices which makes no need for the hub. A sample fugure of a devicewire adapter is shown below

Fig: Device wire adapterHost Wire AdaptersHost wire adapters lies on the WUSB host they are small adapters that look like adongle which can be connected to the USB ports of the host computer. This host wireadapters make use of the wired USB connection to connect to the host PC and thewireless USB technology to connect to the Device wire adapters to which the wirelessUSB devices are connected.The whole connection makes a mixture of wired and wireless conection whichleads to decrease in throughput. It is always recommended to use the wireless hostintegrated into the host system as PCI or PCI(e) device.

Examples

1.WiFi Serial RS232 Adapter

The Battery powered WiFly serial Adapter supports RS-232 interface. When connected to a remote host, the WiFly serial adapter transfers data read.

2.Serial Bluetooth Adapter

Wireless Serial Bluetooth RS232 adapters are probably used more often than wireless serial RF units. The reason is that wireless serial Bluetooth is low-cost, reliable, secure and then many existing devices already have Bluetooth built-in. for example many laptops and GPS devices. By using a wireless serial Bluetooth RS232 adapter for connecting for example a GPS to your laptop you will enjoy the benefits of wireless serial connectivity for only a few more dollars as what a premium wired serial RS232 adapter would cost.

3.Wireless serial Radio Frequency (RF) RS232 modules.

Wireless serial RF modules are often more expensive and requires a bit more configuration than wireless serial Bluetooth RS232 adapters, this may be a reason why wireless serial RF modules are mostly used in business and industrial applications. The advantage with wireless serial RF RS232 modules is that they communicate in the 433.30MHz band, and inherently radio frequency has a longer communication range than wireless serial Bluetooth RS22 adapters, so the communication range for wireless serial RF RS232 modules typically range from 1000 feet to 9800 feet but can go as high as 12 miles or even more.

Advantages The WUSB architecture allows up to 127 devices to connect directly to a host. Because there are no wires or ports, there is no longer a need for hubs.

WUSB host capability can be added to existing PCs through the use of a Host Wire Adapter (HWA).

WUSB performance at launch will provide adequate bandwidth to meet the requirements of a typical user experience with wired connections.

Disadvantages

There are no major drivers for W-USB.

Uses

Wireless USB is used in game controllers, printers, scanners, digital cameras, MP3 players, hard disks and flash drives. Kensington released a Wireless USB universal docking station in August, 2008.

It is also suitable for transferring parallel video streams, while utilizing the Wireless USB over UWB bandwidth.

WUSB in the Future

The first Wireless USB implementations will likely be in the form of discrete silicon that will be introduced in a number of form factors. These may include add-in cards and dongles along with embedded solutions to support the technology's introduction and subsequent rapid ramp up.

But the wireless future will arrive once WUSB, along with the common ultra wideband platform, becomes a standard part of every processor and chipset and is integrated in CMOS silicon.

Conclusion

The first Wireless USB implementations will likely be in the form of discrete

silicon that will be introduced in a number of form factors. These may include add-incards and dongles along with embedded solutions to support the technology'sintroduction and subsequent rapid ramp up.But the wireless future will arrive once WUSB, along with the common ultrawideband platform, becomes a standard part of every processor and chipset and isintegrated in CMOS silicon.As the latest iteration of USB technology, wireless USB (WUSB) will offerthe same functionality as standard wired USB devices but without the cabling. As thenew Wireless USB Promoter Group prepares to develop the specifications that willhelp standardize the technology, the industry is planning products that can takeadvantage of the convenience and mobility that this new device interconnect will offer.

. BIBLIOGRAPHY:

www.wirelessusb.com www.wikipedia.com www.abo.fi/~ipetre/wired www.google.com www.howstuffworks.com