liance SO that devices car- rying its certification mark are interoperable. There are two versions of HomePlug: HomePlug 1.0-HomePlug 1.0 enables speed up to 14Mbps. HomePlug 2.0-Also known as HomePlug AV, HomePlug 2.0 promises a raw data rate of up to 200Mbps, although the practical throughput is closer to 100Mbps. This new standard, while compatible with HomePlug 1.0, can support VoIP and HDTV. The alliance is also now working on a HomePlug BPL standard. Through the use of OFDM modulation, which allows coexistence of several distinct data carriers in the same wire pair, HomePlug brings back the ability to use Ethernet in a bus topology. To deal with the noise problems inherent in the power- line medium, the HomePlug technology uses OFDM as the basic transmission technique. (OFDM, which is widely used in DSL technology and in numerous wireless systems, is discussed in Chapter 13.) It also makes use of a combination of Chapter 12 Broadband Access Alternatives sophisticated forward error correction (FEC), interleaving, error detection, and automatic repeat request (ARQ) to ensure that the channel appears reliable to the network-layer protocols. A nonprofit organization called the Consumer Electronics Powerline Commu- nication Alliance (CEPCA; www.cepca.org) has been formed by Sony (www.sony. com), Mitsubishi (www.mitsubishi.com), and Panasonic (www.panasonic.com). A company with a global effort, CEPCA's main mission is to promote and continu- ously advance high-speed PLT technology to use and implement a new generation of consumer electronics products through the rapid, broad, and open industry adoption of CEPCA specifications. It is important to note that the alliance's main purpose is to promote coexistence rather than to develop a specific technology; in fact, the founders are currently making use of four or more technologies. CEPCA will be working on promoting coexistence in the United States, Europe, and China and encouraging PLT deregulation in Japan while also submitting proposals to the IEEE, ETSI PLT, and