Communication between devices located in the same home is based on the following protocol;

• The connection type: Cable or wireless signals
• If cable, type of cable and number of lines needed.
• Communication schemes
• Serial : one bit at a time in a scheme called serial communications,
• Parallel: groups of bits (usually 8 or 16 at a time).
• The language of commands and responses
• Some types of products have a standard protocol used by virtually all companies
• Some types of products have own special protocol.

As it was mentioned previously, in the residential telecommunication environment there will be different devices with totally different communication protocols broadcasting signal in he same frequency band. This situation brings in some advantages and disadvantages. Advantages; all wireless system working in the same frequency band. This means a communication protocol can easily be established. The filters in the devices are already designed for the frequency band of the interest. On the other than , if any of the device is not using a standard communication scheme than we need to asset the situation to find a solution to include that specific device into the home telecommunication system. This part needs further investigation and research.

1.2. Communication Schemes
There are four types of wireless networks available;

a) Bluetooth: The hardware vendors, which include Siemens, Intel, Toshiba, Motorola and Ericsson, have developed a specification for a very small radio module to be built into computer, telephone and entertainment equipment. Bluetooth communicates on a frequency of 2.45 gigahertz, which has been set aside by international agreement for the use of industrial, scientific and medical devices (ISM).

b) rDA: Infrared Data Association is a standard for devices to communicate using infrared light pulses. The requirement for line of sight is limiting the usefulness of an IrDA network in a typical home layout.

c) HomeRF and SWAP: SWAP devices make 50 hops per second and transmit at 1 Mbps. Depending on the manufacturer, some of these can step up to 2 Mbps if there is very little interference in their operational area.

d) WECA and Wi-Fi: Targeted more at office use than home networks, Wi-Fi is essentially a seal of approval that says the manufacturer's product is compliant with a variation specification known as IEEE 802.11b. Under 802.11b, devices communicate at a speed of 11 Mbps whenever possible. If signal strength or interference is disrupting data, the devices will drop back to 5.5 Mbps, then 2 Mbps and finally down to 1 Mbps.

1.3. Wireless Personal Area Network (WPAN) with Bluetooth

When Bluetooth-capable devices come within range of one another, an electronic conversation takes place to determine whether they have data to share or whether one needs to control the other. One should remember that due to the low power limits the range of a Bluetooth device to about 10 meters.[4]

Let’s consider a typical living room with the typical devices.

• Entertainment system with a stereo
• DVD player
• VCR
• Satellite TV receiver
• Television
• Cordless telephone
• Personal computer

Each of these systems uses Bluetooth, and each forms its own piconet to talk between main unit and peripheral. The manufacturer has programmed each unit with an address that falls into a range of addresses it has established for a particular type of device.

When the base is first turned on,

I. It sends radio signals asking for a response from any units with an address in a particular range.
II. The Cordless telephone handset has an address in the range, it responds, and a tiny network is formed.
III. The computer and entertainment system go through similar routines, establishing networks among addresses in ranges established by manufacturers.

Once the networks are established, the systems begin talking among themselves. Each piconet hops randomly through the available frequencies, so all of the piconets are completely separated from one another.

Now the living room has three separate networks established, each one made up of devices that know the address of transmitters it should listen to and the address of receivers it should talk to. Since each network is changing the frequency of its operation thousands of times a second, it’s unlikely that any two networks will be on the same frequency at the same time.

Because Bluetooth is designed to work in a number of different circumstances, it can be either half-duplex or full-duplex. The cordless telephone is an example of a use that will call for a full-duplex (two-way) link, and Bluetooth can send data at more than 64,000 bits per second in a full-duplex link -- a rate high enough to support several human voice conversations. If a particular use calls for a half-duplex link -- connecting to a computer printer, for example -- Bluetooth can transmit up to 721 kilobits per second (Kbps) in one direction, with 57.6 Kbps in the other. If the use calls for the same speed in both directions, a link with 432.6-Kbps capacity in each direction can be made.

1.4. The 802.15 WPAN (Wi-Fi PAN)

The 802.15 WPAN™ effort focuses on the development of consensus standards for Personal Area Networks or short distance wireless networks. These WPANs address wireless networking of portable and mobile computing devices such as PCs, Personal Digital Assistants (PDAs), peripherals, cell phones, pagers, and consumer electronics; allowing these devices to communicate and interoperate with one another. The goal is to publish standards, recommended practices, or guides that have broad market applicability and deal effectively with the issues of coexistence and interoperability with other wired and wireless networking solutions.

The IEEE 802.15 Working Group is part of the 802 Local and Metropolitan Area Network Standards Committee of the IEEE Computer Society. The IEEE-SA is an international membership organization serving today's industries with a complete portfolio of standards programs. The IEEE has more than 368,225 members in approximately 150 countries. Through its members, the IEEE is a leading authority on areas ranging from aerospace, computers and telecommunications to biomedical engineering, electric power and consumer electronics. [4]

1.4.1. IEEE 802.15.1

The new IEEE Std 802.15.1™-2002 standard is an additional resource for those who implement Bluetooth devices. The lower transport layers (L2CAP, LMP, Baseband, and radio) of the Bluetooth™ wireless technology are defined. Bluetooth is an industry specification for short-range RF-based connectivity for portable personal devices. The IEEE has reviewed and provided a standard adaptation of the Bluetooth Specification v1.1 Foundation MAC (L2CAP, LMP, and Baseband) and PHY (Radio). Also specified is a clause on SAPs which includes a LLC/MAC interface for the ISO/IEC 8802-2 LLC. Also specified is a normative annex which provides a Protocol Implementation Conformance Statement (PICS). Also specified is an informative high level behavioral ITU-T Z.100 Specification and description language (SDL) model for an integrated Bluetooth MAC Sublayer.

1.4.2. IEEE 802.15 WPAN™ Task Group 2

The IEEE 802.15 Coexistence Task Group 2 (TG2) for Wireless Personal Area Networks is developing Recommended Practices to facilitate coexistence of Wireless Personal Area Networks™ (802.15) and Wireless Local Area Networks (802.11). The Task Group is developing a Coexistence Model to quantify the mutual interference of a WLAN and a WPAN™. The Task Group is also developing a set of Coexistence Mechanisms to facilitate coexistence of WLAN and WPAN™ devices.

1.4.3. IEEE 802.15 WPAN Task Group 3

The IEEE P802.15.3 High Rate (HR) Task Group (TG3) for Wireless Personal Area Networks (WPANs) is chartered to draft and publish a new standard for high-rate (20Mbit/s or greater) WPANs. Besides a high data rate, the new standard will provide for low power, low cost solutions addressing the needs of portable consumer digital imaging and multimedia applications.

1.4.4. IEEE 802.15 WPAN™ Task Group 4

The IEEE 802.15 TG4 is chartered to investigate a low data rate solution with multi-month to multi-year battery life and very low complexity. It is intended to operate in an unlicensed, international frequency band. Potential applications are sensors, interactive toys, smart badges, remote controls, and home automation.