29-11-2012, 02:06 PM
Wireless USB
WIRELESS USB lohi.doc (Size: 4.39 MB / Downloads: 34)
ABSTRACT:
Wireless USB is a logical bus that supports data exchange between a host device (typically a PC) and a wide range of simultaneously accessible peripherals. The attached peripherals share band width through a host-scheduled, TDMA-based protocol. The bus allows peripherals to be attached, configured, used, and detached while the host and other peripherals are in operation. Security definitions are provided to assure secure associations between hosts and devices, and to assure private communication. Wireless USB is a wireless technology which enables the high speed computer peripheral interface, USB, wireless. It is a wire replacement of existing USB technology using a Multi Band Orthogonal Frequency Division Multiplexing radio technique.
INTRODUCTION
Wireless USB is a wireless technology which enables the high speed computer peripheral interface, USB, wireless. It is a wire replacement of existing USB technology using a Multi Band Orthogonal Frequency Division Multiplexing radio technique.
Wireless USB interest group was formed in 2004. It is the first high speeds personal interconnect. The physical layer is standardized under IEEE 802.15.3 PHY. Today it is in the developing stage. The major WUSB promoters are HP, Intel, Microsoft, NEC Philips, & Samsung
A USB system consists of a host and some number of devices all operating together on the same time base and the same logical interconnect. A USB system can be described by three definitional areas:
• USB interconnect
• USB devices
• USB host
NEED FOR ANOTHER WIRELESS TECHNIQUE
USB is a fast growing technology and now above 80% of all devices supports USB connectivity to a PC. It will be a great reduce of number of wires and cost for paying the cables, if the existing USB technique goes wireless.
Today, an office PC is disturbed with rat’s nest of cables. By adopting the current wireless technology such as Bluetooth, WiFi, ZigBee, IR, etc doesn't reduces the number of wires since they have not enough bandwidth to support bigger data transfer rate.
USB Hosts
There is only one host in any USB system. The USB interface to the host computer system is referred to as the Host Controller. Host controllers are typically connected to PCs through an internal bus such as PCI. The Host Controller may be implemented in a combination of hardware, firmware, or software. This specification defines another way that a host controller may be 'connected' to a PC. Chapter 8 describes a Wire Adapter device class that allows USB host functionality to be connected to a PC through a USB connection (either wired or wireless). Wire Adapters that directly connect to the PC using wired USB are known as Host Wire Adapters. Host Wire Adapters add Wireless USB
Capability to a PC. Wire Adapters that are Wireless USB devices and hence connect to the PC wirelessly are known as Device Wire Adapters. Device Wire Adapters typically have USB 'A' connectors (i.e. they look like wired hubs) and allow wired USB devices to be connected wirelessly to a host PC. Note that each Wire Adapter creates a new 'USB system', in that there is one host (the wire adapter) talking to one or more devices using the same time base and interconnect. Wire Adapters are important enabling devices for Wireless USB. Host Wire Adapters enable existing PCs to support Wireless USB. Device Wire
Adapters allow existing wired USB devices to have a wireless connection to the host PC.
Physical Interface
Physical layer of Wireless USB is described in the Multi band OFDM Alliance (MBOA) UWB PHY specification, see reference [4]. The PHY supports information data rates of 53.3, 80, 106.7, 200, 320, 400 and 480 Mb/s and multiple channels. The PHY also provides appropriate error detection and correction schemes to provide as robust a communication channel as possible. For Wireless USB devices, the support of transmitting and receiving data at rates of 53.3, 106.7, and 200 Mb/s is mandatory. The support for the remaining data rates of 80, 160, 320, 400 and 480 Mb/s is optional. Wireless USB Hosts are required to support all data rates for both transmission and reception. All Wireless USB
Power Management
A Wireless USB host may have a power management system that is independent of the USB. The USB System Software interacts with the host's power management system to handle system power events such as suspend or resume. Additionally, USB devices typically implement additional power management features that allow them to be power managed by system software. This specification defines mechanisms and protocols that allow hosts and devices to be as power efficient as possible.