Broadband Wireless and Bluetooth-Based Communications

Broadband Wireless and Bluetooth-Based Communications Networks

Fundamentals of Broadband Wireless and Bluetooth-Based Communications Networks

The intent of this paper is to explain the fundamentals of broadband wireless and Bluetooth technologies. Each of these communications technologies and their associated protocols are experiencing exponential growth as a result of WiFi locations or "hotspots" becoming pervasive globally to support and compliment the growth of PDAs, convergence devices and laptop computers that are continually dropping in price. Correspondingly the Bluetooth standard continues to gain greater adoption throughout cellular telephone use, networking of cellular, personal digital assistants (PDAs), and devices that include the convergence of audio and video-based cellular communications. What unifies these two standards is their position within the Open Systems Interconnect (OSI) Model which is shown in Figure 1.

Figure 1: The Open Systems Interconnect (OSI) Model

Source: (Cisco Tutorial 2007)

Both broadband wireless and Bluetooth concentrate their protocols on the Data Link and Network layers of the OSI Model as shown in Figure 1. The major differences between these two protocols are specifically attributable to how each manages the physical-to-logical connections of devices to networks (Chek, Kwok, 2007).

Fundamentals of Broadband Wireless and Bluetooth

In analyzing both broadband wireless and Bluetooth technologies, it's important to anchor the analysis first by the current state of wireless computing, analyzing market characteristics according to three dominant functional areas including access techniques, frequency spectrum and system architecture attributes and components of a given system. These three factors comprise the current foundation of the both broadband wireless and the adoption of Bluetooth globally (Diegel, Bright, Potgieter, 2004).

Broadband wireless and Bluetooth technologies share a common series of access techniques that encompass four dominant multiplexing standards forms the foundation of wireless computing platforms (Fantacci, Vannuccini, Vestri, 2008). These include code-division multiplexing (CDM), frequency-division multiplexing (FDM), space-division multiplexing (SDM) and time-division multiplexing (TDM). Broadband wireless and Bluetooth technologies each support these four access techniques, yet Bluetooth differs from broadband wireless in its approach to defining a highly unique packet architecture which is specifically designed to allow for more efficient network traffic. As Bluetooth also operates within a significantly different frequency spectrum of broadband wireless, the need for synchronization of logical-based transport links that ensure connectivity to the physical level (or network connection level) as conceptually defined with the OSI Model with logical link function of the Data Link layer is critical for communication to occur. Figure 2 shows how at the Network Layer both broadband wireless and Bluetooth are capable of communicating with one another over the Transport Layer of the OSI Model.

Sources: (Cisco, 2007), (Kuran, Tugcu, 2007)

The four approaches to managing access are specifically designed to ensure broadband wireless and Bluetooth-based networks can be configured to take into account differences in code, frequency, time and spatial differences in optimizing their communications configurations. As the OSI Model provides for a wide variation in communications scenarios and the protocols that underscore both broadband wireless and Bluetooth-based networks have become more aligned with the needs of commercial and consumer customers for higher levels of integration across the two standards (Kuran, Tugcu, 2007). Researchers continue to look at the potential for degradation of traffic between broadband wires and Bluetooth-based networks, and the most significant finding has been found though (Chek, Kwok, 2007).

The integration requirements of users is forcing a series of technological developments to provide for data synchronization and multiplexing across broadband wireless Bluetooth networks (Chek, Kwok, 2007). The design objectives of these four multiplexer approaches therefore are to increase the spectral efficiency through the use of optimal multiplexing depending on the configuration requirements of the shared network. Measured in bits per second per Hertz, spectral efficiency is defined to be the throughput per frequency spectrum available given the receiving and sending devices' baseline or native protocol.

In conjunction with the use of time division multiplexing techniques is the reliance on collision avoidance (CA) and collision detection (CD) approaches to managing time-division-based multiple access across a broadband wireless network and in peer-based configurations of Bluetooth networks. The concepts of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) and Carrier Sense Multiple Access/Collision Detection (CSMA/CD), originally defined as part of the Open Systems Interconnect Model (OSI Model) and later supported extensively throughout TCP/IP. Its use throughout broadband wireless networks has predominantly focused on the CSMA/CD approach to managing packet traffic throughout broadband wireless networks as this provides greater support throughout hybrid networks. The use of four different approaches to multiplexing in conjunction with the use of the CSMA/CD techniques for intermediating network traffic and ensuring each device and task on a broadband wireless network can gain access to the Internet is the concept behind metro-based WiFi plans of Google for example. Blanketing a metro area with overlapping signals gives broadband wireless networks more reliability and a greater level of redundancy and consistent performance over time. WiFi-based broadband networks also rely extensively on frequency spectrum considerations and systems architectures to ensure there is a consistent level of wireless network performance.

The next major aspect of the current state of broadband wireless computing networks is the frequency spectrums used to enable signal transmission throughout the network. This is also an area that continues to gain increased attention from the standpoint of integration between IEEE 801.11b-based broadband wireless networks and Bluetooth-enabled smaller networks (Chek, Kwok, 2007). The frequency spectrum for broadband wireless networks is based on available radio frequency bandwidth, and has integration points in the Data Link Layer of the OSI Model as has been shown earlier in this paper. PDAs, convergence devices and laptops that have the option of being configured with either broadband wireless or Bluetooth protocols rely on the Data Link Layer to, in the case of CMSA/CD-based networks, arbitrate the specific aspects of the network to ensure connectivity is possible.

Broadband wireless networks and Bluetooth devices and their predominately peer-based networks are further defined by the configuration options network operators and service providers choose in defining the frequency spectrum of the network created. The well-known and pervasively supported standard of IEEE 802.11 is used as the basis for defining frequency spectrum levels for broadband wireless networks yet is increasingly being integrated with from a Bluetooth platform level as well (Chek, Kwok, 2007). The IEEE LAN/MAN Standards Committee defines standards in the 2.4GHz to 5 GHz public spectrum bands used for over-air modulation and demodulation of signals. The popular term WiFi is synonymous and is in fact another word for the 802.11 standard. This standard is the foundation of integration between broadband wireless and Bluetooth networks (Chek, Kwok, 2007).

Currently there are five variations of the 802.11 standard in existence, with the latest one due to be formally introduced in 2008. Beginning in 1999, the 802.11a standard was released, supporting an operating frequency of 5 GHz and operating at 23 Mbits/second, using an OFDM Modulation technique. Later in 1999, the second standard, 802.11b was introduced, supporting a 4.3 Mbit/second throughout rate with a maximum rate of 11 Mbits/second rate. The 802.11g standard was first introduced in 2003, and also supported a 2.4 GHz operating frequency and 19 Mbits/second throughput rate. The 802.11y protocol is due to be released in June of 2008 and will support an operating frequency of 3.7 GHz and a 23 Mbits/second throughput rate. The committee has also said that 802.11n will be released in June, 2009 and support 2.4 and 5 GHz operating frequencies and a throughput of 74 Mbits/second. The 802.11 set of standards are enabling video downloads and the en mass migration of social media to support real-time messaging and video messaging over simple text messaging. The implications of the rapid progression of the 802.11 standards also are the foundation of optimistic forecasts on the use of digital entertainment including movie and digital content downloads through WiFi networks. Researchers also see the opportunity to make wireless computing location- and context-knowledgeable to ensure there is a higher level of personalization and contextual content available to users of WiFi-enabled devices. The 802.11 standards provide the frequency spectrums for an exponential increase in throughput and therefore the use of broadband wireless computing networks. The research of (Chek, Kwok, 2007, (Kuran, Tugcu, 2007) are concentrating on how to integrate Class 1, 2 and 3 levels of Bluetooth radio frequencies at the protocol level into the IEEE 802.11 standard. Bluetooth's most powerful radio frequency is Class 1 which can operate at approximately 100 meters, and is the closest to gaining a high level of interoperability with the higher speeds of the IEEE 802.11 standards.