Picking the right technologies for your home network design

Munish Mangal and Nishant Omar

November 10, 2009

Munish Mangal and Nishant OmarNovember 10, 2009

Over the last few years, a great expansion in the variety of remote control devices has occurred in our day-to-day life. A few years back, IR remotes for the TV were the only such devices in the homes. But today, almost all the electronic devices are controlled using a remote, which results in large numbers of remotes in our homes.

Now the question arises as to why we need a lot of remotes. Devices such as TVs, garage door openers, light and fan controls etc. predominantly necessitate one-way, point-to-point control.

They're not interchangeable, and they usually don't support more than one device. Because most remotely controlled devices are proprietary and are not standardized among manufacturers—even those remotes used for the same function (like turning on and off lights) are not interchangeable with similar remotes from different manufacturers.

In other words, the consumer has as many separate remote control units as devices to be controlled. To solve this problem, the universal remote controllers with learning capability are already in the market for the last few years.

But because of their line of sight and short range of communication and limitation in the number of supported devices, they find only limited use in the home entertainment segment.

In addition to comfort, home security is a consumer's significant concern. Home security systems like burglar alarms, motion detectors and surveillance cameras are already emerging as popular products in the market. But these products offer somewhat limited security.

All these needs have triggered the requirement of a home network that can control and monitor a number of devices without any line of sight or range limitations. A home network is a method of allowing different devices to communicate with one another.

In a home network, one or more devices have the power to monitor or control the other devices in the network. Generally the home networks are used for communication between digital devices used within the household, usually a small number of PCs and accessories, such as printers and mobile computing devices. The major purpose is the sharing of Internet access (often a broadband service through a cable TV or DSL provider) or sharing of files and utilities.

Today, however, home networks are finding extended applications involving data collection from several devices or specific sensors for centralized control from a single control unit that monitors the premises even when one is far away.

This article explores various home network techniques and the application possibilities with an implementation example. It also further explores Zigbee as the choice for a localized home network and explores the possibility of GSM for remote operation.

Implementation techniques
A home network was implemented in 1978 for the Sears Home Control System and the Radio Shack Plug'n Power System. It used power-line wiring to send and receive commands. After this, a lot of technologies have been explored for home networking, ranging from wired networks to wireless.

With the advancement of technology, Ethernet became the traditional choice in homes, but wireless technologies are gaining ground fast. While both wired and wireless technologies claim advantages over the other, both represent viable options for home networking.

In wired networks, one or more devices are connected through cable to a central hub through routers or repeaters. The central hub is connected to a user interface from which it gets the commands and in turn sends them to the connected devices (Figure 1 below).

Figure 1: In wired networks, one or more devices are connected through cable to a central hub through routers or repeaters.

Of the various wired technologies, Ethernet 10/100Mbps is the most popular network method because of the low price of the network cards, reliability and speed; but this comes with the initial trouble of laying out the network cabling within the household; future expansion to cater for newer devices may not be possible or very limited.

HPNA, also called PhoneLine or HomePNA, is another home networking technique. Its advantage is that it works over the existing copper telephone wires in the home without interfering with voice or DSL communications.

But this offers a speed of only 10Mbps. FireWire networking is supported by most of operating systems these days. This is most suitable for the short-range high-speed communication. Apart from these approaches, there are other wired technologies like PLM, Ethernet Gigabit and USB.

A common problem in wired topologies is that they are difficult to be done in existing homes and don't give much freedom to move nodes from one place to another. Installation is difficult and costly, thus restricting user flexibility.

The wired network's installation difficulty has encouraged wireless networks. In wireless networks, the devices are connected to a central hub or station using a wireless communication standard, which in turn interacts with the user interface (Figure 2 below).

Figure 2: In wireless networks, the devices are connected to a central hub or station using a wireless communication standard, which in turn interacts with the user interface.

The popular wireless technologies for home networking include Wi-Fi, Zigbee, wireless HomeRF and Bluetooth.

To maintain uniformity among different vendors, all the wireless communication protocols follow some IEEE standards. Although wireless technologies may suffer from signal interference, higher cost and lower data rate compared with wired ones, they offer more desirable features like easy installation, easy accessibility and enhanced user friendliness.

Lower data rate does not block the road of wireless technology in home networking, as the offered data rate is sufficient for control and monitoring applications, and signal interference is taken care of by software techniques. Moreover, adding a new device to the existing network is as simple as just switching it on. Table 1 below compares the various networking technologies in terms of speed, range and cost.

Table 1: Here's a comparison of the various networking technologies in terms of speed, range and cost.

Wireless home networks are getting even more popular day by day. Depending on user requirements, home networks can be developed using wired or wireless, or mixed technologies (Figure 3 below).

Figure 3: Depending on user requirements, home networks can be developed using wired or wireless, or mixed technologies, which is shown above.

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