WIRELESS USB

ABSTRACT

            WUSB (Wireless Universal Serial Bus) is ideal for point-to-point connections from PC to PC, PC to a peripheral like printer or camera, and peripheral to peripheral, like a digital camera to printer. The overhead required for maintaining the hardwired networks cost of cabling, manpower and time is eliminated using wireless technology.  Wireless serial technology creates virtually endless new opportunities in the way companies conduct business. Wireless connectivity provides mobility that was previously unavailable without increase in the cost and inconvenience of installing new cabling.  The flexibility of wireless makes WUSB an ideal solution for many applications, including point-of-sale, industrial control and simplified LAN expansion. By using WUSB Connect the device like as printer external hard drive and digital Camera to your pc .Without a single wire and still get a speed and security of a wired connection. the WUSB chipset is highly compact and can be built in to the Product .the technology approaches to wireless USB dongles ,wireless internet connection Sharing through USB, wireless printers sharing through USB ,wireless digital camera.

This paper presents an overview of WUSB by explaining the operation, features and various applications the impact of WUSB on wireless technology. The paper also provides a future agenda in this area.

Introduction

            Today the wireless technology field is very fast growing area with the number of users and their demand for better re-sources and equipment increasing day by day. Wireless USB will build on the success of wired USB, bringing USB technology into the wireless future. Usage will be targeted at PCs and PC peripherals, consumer electronics and mobile devices. To maintain the same usage and architecture as wired USB, the Wireless USB specification is being defined as a high-speed host-to- device connection. This will enable an easy migration path for today’s wired USB solutions.

                The growing use of wireless technology in PC, CE, and mobile communications products, along with the convergence of product functionalities, calls for a common wireless interconnect standard. The standard needs to work well with products and usage models from all three industries. To better understand what’s driving the need for a common standard, we’ll examine how wireless USB products will soon be used in home and business environments. We’ll also consider the rise of “dual-role” devices that include both host and device capabilities. the Wireless USB is highly compact and can be build directly into product. Whether it is digital camera or USB printer, USB makes USB connectivity easier than ever before

 Architecture of wireless USB

The architecture of Wireless USB is a classic hub-and-spoke, where the host (the user’s PC) communicates directly with up to 127 USB devices .Communications with each device is scheduled to simplify the management of communications with multiple

devices. The physical layer (PHY)—the radio portion and its interfaces—is defined by the MB-OFDM specification. The PHY supports data rates of 53.3, 106.7 and 200 Mb/s (required) and 80, 160, 320, 400 and 480 Mb/s (optional). Wireless USB hosts must

support the same data rates for both transmit and receive. The PHY defines all hardware

interfaces, such as the types of connectors and pin function assignments, as well as the radio functions, including modulation type, frequencies of operation, power control, and other characteristics that must be part of the base band-TX-propagation- RX-base band chain. A typical OFDM transmit chain is shown in Figure 1. Note that, as a time-domain based transmission method, UWB uses inverse-FFT in the transmitter and FFT in the receiver. These processes have the additional benefit of easily handling narrowband interference—either received or transmitted. Using FFT techniques, a single-frequency can be eliminated (“notched”) with minimal effect on the transmission quality.

Figure 1 · A typical UWB MB-OFDM transmit chain for Wireless USB

Product being developed by companies

1.      Cypress Semiconductors

2.      Intel

3.      Topcom

The single chip CY694X comprises a 0.25 micron Bi CMOS radio frequency transreciver and 0.25 micron CMOS base band that does setup and break down of links, packet framing error checking, and any real time operation. The base band also includes an applications engine. They consume less than 10 microamperes in stand by mode. Its power amplifier output of 4 dBm translates to 0 dBm at the antenna like as Bluetooth.

Similar in many to Bluetooth, the CY694X uses a frequency-hopping spread sprectum scheme with 1600 hops/second over 79 channels in 1MHz band. But unlike Bluetooth, it uses 2FSK modulation and 10/15 Hamming-code forward error correction for max data rate of 217.6 Kbps over a range of 10 meters or more. The CY694X supports 7 nods per host and multiple separate links in the same space. Using frequency-hopping spread-spectrum technology, it allows use of multiple wireless USB devices in crowded offices and classroom without the fear of interference between devices. Advance power management enable batteries to last up to 6 months in typical keyboard applications. bidirectional communication makes it possible to encrypt the transmitted data, ensuring a high level of security .

                  Operating at 2.4GHz, the same frequency as used by Bluetooth and 802.11b wireless networks, the CY694X can connect as many as seven devices up to 10 meters apart, making wireless USB low cost wireless RF solution and possibly an alternative to Bluetooth.

What is frequency-hopping spread-spectrum

     

It is a form of wireless communication in which the frequency of the transmitted signal is deliberately varied. Frequency-hopping spread-spectrum (FHSS) utilizes conventional modulation techniques o0n the RF carrier, but the carrier is not fixed; instead it varies in frequency according to a pseudorandom coded sequence. Near-term distribution of hopes appears random, the long-term distribution appears evenly distributed over the hop set, and sequential hops vary randomly in both direction and magnitude of change.

Advantages of FHSS

1)      Better voice quality/data integrity.

2)      Less static noise.

3)      Lowered susceptibility to the multipath fading.

4)      Inherent security.

 Topology

The fundamental relationship in Wireless USB is the “hub- and-spoke” topology, as shown in Figure 2. 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 Wireless USB host and Wireless USB device. The main difference here from wired USB case is that there are no hubs present in the connection topology. The Wireless USB host can logically connect to a maximum of 127 Wireless USB devices. Wireless USB clusters co-exist within an overlapping spatial environment with minimum interference, thus allowing for a number of other Wireless USB clusters to be present within the same radio cell. In addition to providing wireless connectivity, Wireless USB will be backward compatible with wired USB and provide bridging to wired USB devices and hosts. A method will be required to enable the exchange of data between clusters or devices not related to the same host. This method may be a second-level connection between two hosts (i.e., a network) or some method of transferring data between two clusters not managed by the same host.

  

Figure (2)

  

Application

Home applications

The trend towards smaller form factors, portability and mobility in consumer electronics devices has led to the emergence of new classes of products. These products have rich functionality, multimedia capabilities, and require connection to other AV devices for display, editing, listening, sharing, and downloading of content. Within the home, for instance, a family may have a digital video camcorder, digital still camera, portable MP3 player, PDA, tablet PC, wireless speakers, and personal video display device Each of these portable devices has a need to connect to other devices such as PCs or stationary consumer electronics products, such as stereos, HD TV s, video recorders, entertainment PCs, or the like. All these devices would benefit from the ability to connect without cables. Think, for instance, about the number of devices in your home and the tangle of wires between them. Wireless USB would eliminate these wires and enable devices to wirelessly connect to each other.

Figure 3. Home usage scenarios that could be “unwired” with Wireless USB.

  

Naturally, the CE environment will have high expectations for performance. Many consumer usage models will center on demanding streaming media distribution using compression algorithms. Typical video delivery with standard SDTV/DVD can consume between 3 to 7 Mbps, while HDTV can require between 19 to 24 Mbps. A point distribution technology like Wireless USB with its projected effective bandwidth of 480 Mbps, could manage multiple HDTV streams while still having the capacity to support other high-bandwidth data streams. Host buffering could enable a network backbone to effectively distribute content to all distribution hosts, enhancing the quality experience for all users. The Wireless USB specification will be an effective way to ensure that the delivered convenience and quality of service meets typical consumer entertainment expectation

 Office/Business application

             Connectivity issues and other inconveniences of wired connections can hurt productivity and slow the adoption of new devices within the work environment. Users of mobile computers and PDAs particularly face connection challenges as they move from place to place and want to use printers and other devices. Wireless USB could simplify their lives while providing a time-saving, high-speed connection that enhances productivity (see Figure 4). In this section, we give some typical scenarios of how Wireless USB could enhance connectivity in the office.

      Executives, managers and heavy users need faster, dedicated services in their office rather than those shared on the network. With Wireless USB, devices such as inkjet and laser printers, scanners, external storage devices, and PC cameras can quickly connect and exchange data at high speed. Top Wireless USB uses will probably include: simultaneous and frequent-use mass storage for data back- up, printer connectivity, scanner connectivity, and PDA or cell phone synchronization.

Printing to Enterprise Printer

       For office workers that are very mobile and frequent differ- ent areas of an enterprise, the option of easily printing from a mobile platform (notebook PC, PDA, cell phone, etc.) is very attractive. With Wireless USB, a worker could simply approach the nearest printer or multi-function device and print the needed documents. This would alleviate many of the inconveniences today in finding a printer on a network and connecting to it.

Sharing of Peripheral Devices

Wireless USB will enable colleagues to more easily share devices and use each other’s devices within an office environment. Easy sharing of scanners, printers, storage devices, and other possible peripherals would be possible. Exchanging large files off hard disk drives without sending them through e-mail or over the network would be possible.

Dual-role Devices

A new class of Wireless USB dual-role devices is projected to eliminate wires in many usage scenarios and enable new uses not previously possible. These devices will offer both limited host and device capabilities, similar to that experienced with USB On-The-Go. (USB OTG is the wired USB specification defining dual-role devices which can act as either hosts or peripherals, and can connect to PCs or other portable devices through the same connector.) Figure 5 shows some dual-role device usage scenarios. More detailed descriptions of various scenarios are also provided.

Figure(5)

Camera to Printer

Wireless USB could enable people to wirelessly download and print digital photos to a color printer. Imagine taking pictures at an amusement park and being able to share copies immediately by transmitting the pictures to a printer at a digital photo kiosk.

MP3 Player to Wireless Speakers

Many people already carry their music wherever they go. Imagine being able to connect to high quality surround sound speakers wherever you are. With Wireless USB, you could forget cables. Just hit play and listen.

Wireless USB vs. Bluetooth

Unlike similar wireless technology, such as Bluetooth or Wi-Fi, wireless USB is not 100percent networking solution. It works on simple point to point basis. This allows, for e.g., keyboard with PC, enabling fast, simple communication between PC and USB device. Bluetooth is short range cable replacement technology that was originally conceived by radio engineers as low cost, convenient and flexible communication technology that would enable any manner of electronics devices to communicate with one another using common protocol. It is regarded by most as truly all pervasive technology that will enable user to experience “out of box” communication with unknown, public or shared electronic devices. Bluetooth uses the unlicensed 2.4-2.483 GHz industrial, scientific and medical (ISM) band.

Unlike Bluetooth, wireless USB provides high level compatibility with existing USB HID software stacks, making it easier for peripheral and PC developers to roll out the technology. It is primarily targeting keyboard, mouse and game controller makers, but may extend to other roles, such as wireless printing, where Bluetooth has had relatively little success. However, wireless USB is not of much use for some of the other Bluetooth application, most notably digicam picture transfers and PDA syncronisation, largly because all these demand more bandwidth than wireless USB can supply. Synchronizing a PDA using Bluetooth is slower than using a USB cable but not enough to outweigh the benefit of eliminating cable.

Wireless USB technology will support the following features

·         Simple, low-cost implementation. The implementation will follow the wired USB connectivity models as closely as possible to reduce development time and to preserve the low-cost, ease-of-use model which has become pervasive in the PC industry.

·         A point-to-point connection topology supporting up to 127 devices that follows a similar host-to-device architecture as used for wired USB.

·         High spatial capacity in small areas to enable multiple devices access to high bandwidth concurrently. Multiple channel activities will be able to occur within a given area. The topology will also support multiple clusters in the same area. The number of clusters to be supported is yet to be determined

·         dual-role model where a device can also provide limited host capabilities. This model would allow mobile devices to access services with a central host supporting the services (i.e., printers and viewers). It would also allow devices to access data outside a cluster they are connected to by creating a second cluster as a limited host

·         Transparent wireless USB connection

·         Full speed USB 1.1 compliant

·         2.4GHz of RF band for the use in most regions of the world

·         Range up to the 300metres when outdoor and up to the 100 metres when indoor

      ·         3-15MBPS data rate

·         Direct sequence spread spectrum

·         Low power consumption

·         Complies with other 802.11b/g devices

·         Supports windows 98 SE /2000/ME/XP

Future

A completed Wireless USB specification is expected by year’s end. The first Wireless USB implementations will be in the form of discrete silicon that will be introduced in a number of form factors. These include add-in cards and dongles, along with embedded solutions to support the technology’s introduction and subsequent rapid ramp-up. The wireless future will truly arrive once Wireless USB, along with the Common Ultra-Wideband Platform, becomes a standard part of every processor and chipset, integrated in CMOS silicon. The goal is for Wireless USB to become the wire- less interconnect of choice for desktop and mobile PCs, handheld, mobile, and consumer electronic devices, allowing easy connection and data exchange at high speeds without wires.

Reference

1.      Universal Serial Bus – www.intel.com/technology/usb

2.      Electronics For You   Aug. 05

3.      September 2005 High Frequency Electronics -www.wimedia.org.