Wireless Network Guide

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Contents

This page is designed to provide a comprehensive tour on all the documentation about the wireless subsystem currently provided in the OLPC wiki.

The XO Wireless Network Guide

XOs are 802.11b/g compatible devices (operating in the unlicensed ISM band at 2.4GHz). Its wireless subsystem is built on a Marvell 88W8388 SoC along with a 88w8015 RF transceiver and it is connected to the main cpu (AMD Geode LX700) via an internal USB interface.

Its two rotating "bunny ear" antennae [create page on antennae] support reception diversity and can be redirected to improve reception. Two LEDs indicate the status of the wireless subsystem.

Besides having all the capabilities of a regular wi-fi enabled laptop, the XO implements a layer 2 multihop wireless network (Mesh Network Details) based on IEEE802.11s, that allows it to communicate to other XOs even if no infrastructure (access points) is present.

Two software components implement the wireless subsystem. The Libertas Driver (part of the Linux Kernel) and the Libertas Firmware. The Libertas driver is a mainline linux kernel driver with extra features that support XO-only needs and capabilities. The Libertas firmware is kept by Marvell.

XOs are capable of operating in the following modes:

  • managed (infrastructure) mode - connected to 802.11b or 802.11g access points as regular 802.11 stations.
  • mesh mode - connected to each other in a "mesh cloud" with no need of any infrastructure (access points)
  • ad hoc mode - connected to a IBSS as part of the 802.11 standard (ad hoc mode should not be confused with ad hoc networks)
  • master mode - providing connectivity to other stations, i.e. acting as access points.

XOs are also capable of sharing its (Internet) connectivity with other XOs. We used to call this feature MPP (Mesh Portal Point) but we now simply refer to this as Shared Connectivity (so to avoid some confusion with the IEEE802.11s definition of MPP).

Active antennae are the perfect connectivity companion to the XO. They can extend range when connected to an XO or extend mesh coverage when installed in stand-alone mode (not connected to any host). They can also be added to regular PCs and enable them in the mesh.

OLPC and a lot of volunteers have developed tests and tools for the wireless subsystem. If you are interested in learning more about the XO wireless network and/or help develop, test and debug, we suggest that you start by following the links provided in this page (that will lead you to even more links and pages).

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