In the home network scenario, there are likely to be many stubs with terminat- ing loads of various impedances. At some frequencies, the transmitted signal may arrive at the receiver with little loss, while at others, it may be very noisy. Typical sources of noise are dimmer switches, switching power supplies, brush motors, and halogen and fluorescent lamps. In addition, the conditions on the powerline change, for instance, as users plug in new devices. This means that the nature of the channel between outlets may vary a great deal, resulting in differences in the quality of transmission as well as the amount of bandwidth available to carry data. Another issue is that the flexibility of a PLT HAN depends on the availability and placement of the power sources. Another important consideration is the topol- ogy of the power distribution to the home. In the United States, a distribution transformer provides power to a small number of homes (8 to 10). While the dis- tribution transformer does a good job of blocking the powerline networking sig- nals from crossing into the main power grid, it does not prevent signals from crossing between homes powered by the same distribution transformer. This means that the networking signals from your home could show up on the power- line in any of the other homes served by the same source, creating privacy and security concerns similar to those experienced with wireless networks. In order to provide a reliable communications channel over powerline, the proposed solution must include both robust physical layer (PHY) specifications and an efficient MAC protocol. Again, the PHY defines the basic packet formats, coding, and modulation, and the MAC protocol controls how multiple clients share the medium. The HomePlug Powerline Alliance (www.homeplug.com) plays a critical role with its global HomePlug standard for PLT. HomePlug-certified products connect computers and peripherals that use Ethernet, USB, and IEEE 802.11. The HomePlug Powerline Alliance certifies products for HomgPlug comp