User's Manual

Table Of Contents

Rev 1.34, June 2, 2004

also acquires and tracks the incoming signal to extract correct bit values. The RF-Transceiver

modulates or demodulates the UWB signal for each of the two fingers. It also supplies data and

control signals to (transmit mode) or receives them from (receive mode) the Base Band

Controller.

In the receive state, the RF Transceiver accepts the UWB signal from the antenna, filters and

amplifies it, then extracts data and data and error (control) signals and supplies these to the

XSI123 Base Band Controller for further processing.

UWB transceivers operate in one of three modes:

• Continuous transmit mode. A single header and one very long frame (one long payload)

are sent in this mode. This mode is used only for FCC compliance testing.

• Bridge mode. In bridge mode the MAC transfers data or “bridges” between the 1394 bus

and the radio link. Frames are sent by a source transceiver and acknowledged by a

destination transceiver in this mode. This is the standard mode of operation. Frames in

this context refer to Motorola radio frames.

• PERT mode. The PERT, or Packet Error Rate Test, mode is used for sending and

receiving test frames and reporting associated statistics. This mode is used to measure

the performance of a radio link. The MAC generates UWB radio frames that contain

pseudo random data. The UWB frames is transmitted only once to a receiver and must

be acknowledged. There are no frame retries. The receiver station validates the contents

of the frame.

See the Motorola UWB Software Development Kit Utilities Guide for additional information about

the software used to operate a UWB transceiver in one of these three modes.

4.1. MAC Subsystem Overview

The Motorola UWB transceiver contains an 802.15.3-like MAC implemented using an Altera

FPGA, the MC270141. In addition to the MC270141, the MAC subsystem has flash ROM,

SRAM, a serial boot EEPROM and a memory used to configure the MC270141 after every reset

or power-on. Two serial ports are implemented on the MC270141 as is DMA and other control

circuitry. The serial ports are brought to the external RS-232 connector that protrudes through

the WDK enclosure.

As stated above, the MAC protocol built into the WDK is defined by the IEEE 802.15.3

standard, which is a TDMA (Time Division Multiple Access) based MAC. When the WDK is

powered on, it remains quiet until the application enables the radio to “wake-up” because the

user desires to communicate with another device. In wake-up mode, the radio listens and scans

to see if there are other piconets that it might connect to. If none is found, it assumes the role of

“piconet node controller” (PNC). In this role, it transmits a short coded-sequence

synchronization signal (“beacon” – on the order of 0.5 millisecond) and then listens for a much

longer period of time (on the order of 50 milliseconds) to effectively poll for other devices

wanting to join the piconet. The PNC manages the piconet by accepting/authenticating devices

into the piconet, assigning communication time slots to the various devices in the piconet, and

by passing the role of PNC to another device, as appropriate. Therefore, each radio is only

transmitting during: (1) it’s brief beacon period and (2) its communication time slot. A device in a

piconet that does not have data to pass is not assigned a time slot, so it simply sleeps until the

next beacon period. By virtue of this protocol, the requirements of Section 15.517(a)5 of the

FCC Rules are met.