Wireless Network Functions
Conventional Ethernet networks rely on cables connected to computers via hubs and switches. This limits the computer’s mobility and requires that even portable computers be physically connected to access the network. The optimal alternative is wireless networking.
Wireless networks use network cards, called Wireless Network Adapters (WAP), that use radio signals or infrared (IR) signals to send and receive data via a Wireless Access Point (WAP). The Wireless Access Point uses the RJ-45 port to connect to a 10BASE-T or 10/100BASE-T Ethernet hub or switch. A radio transceiver, encryption, and communications software are incorporated. It converts conventional Ethernet signals into wireless Ethernet signals that are transmitted to wireless network adapters, and performs a reverse transfer of signals from wireless network adapters to the conventional Ethernet network. WAP devices come in different standards, and some provide the Cable Modem Router and Switch functions.
Wireless Network Standards
The early days of wireless networking were single-vendor proprietary solutions that were technically incompatible with wireless network products from other vendors. In 1997 the IEEE 802.11 wireless Ethernet standard was developed. Wireless network products developed with this standard are capable of being vendor neutral.
The IEEE 802.11 wireless Ethernet standard consists of the IEEE 802.11b standard, the IEEE 802.11a standard, and the most recent IEEE 802.11g standard. IEEE 802.11 was the original standard for wireless networks endorsed in 1997. It operated at a maximum speed of 2 Mbps with sustainable interoperability of wireless products from different vendors. Yet the standard was found to have some issues that complicated compatibility between devices.
To maintain compatibility, partnering companies formed the Wireless Ethernet Compatibility Alliance (WECA), officially dubbed the Wi-Fi Alliance, to ensure product compatibility. The term Wi-Fi is now attributed to any IEEE 802.11 wireless network products that have passed the Wi-Fi Alliance certification tests.
IEEE 802.11b, also known as 11 Mbps Wi-Fi, operates at a maximum speed of 11 Mbps, slightly faster than 10BASE-T Ethernet. Most IEEE 802.11b hardware functions at four speeds, and varies between using three different encoding types depending on speed and range. It operates at 11 Mbps or 5.5 Mbps using quaternary phase-shift keying/complementary code keying (QPSK/CCK), at 2 Mbps using differential quaternary phase-shift keying (DQPSK), and at 1 Mbps using differential binary phase-shift keying (DBPSK).
As distances vary and signal strength is enhanced or weakened, IEEE 802.11b hardware switches to the most suitable data-encoding method. Wireless networks running IEEE 802.11b standard operate on 2.4 GHz radio frequency bands used by many portable phones, wireless speakers, security devices, and the Bluetooth short-range networking.
Though widespread use of these products can create conditions for interference, the short range of wireless networks (indoor ranges up to 300 feet and outdoor ranges up to 1,500 feet, depending on the by product) minimizes this. Spread-spectrum is a method used by many devices to decrease potential interference. IEEE 802.11b networks connect to wired Ethernet networks or can be used as independent networks.
IEEE 802.11a uses the 5 GHz frequency band offering higher speeds, reaching a maximum speed of 54 Mbps. The 5 GHz frequency band also assists in diminishing interference from devices with lower-frequency IEEE 802.11b networks.
IEEE 802.11a hardware maintains relatively high speeds at both short and long distances. IEEE 802.11a uses the 5 GHz frequency as opposed to the 2.4 GHz frequency band used by IEEE 802.11b, therefore standard IEEE 802.11a hardware cannot communicate with 802.11b hardware. Dual-band hardware resolves this issue.
Dual-band hardware is compatible with either IEEE 802.11a or IEEE 802.11b networks, allowing a user flexibility bouncing between an IEEE 802.11b wireless network at home or coffee house to a faster IEEE 802.11a office network.
IEEE 802.11g is also known as Wireless-G and integrates compatibility of IEEE 802.11b with the speed of IEEE 802.11a at long distances. In 2003 the standard was authenticated, however, many network vendors were selling products based on the draft IEEE 802.11g standard before the final standard was approved. IEEE 802.11g hardware was slower and less in accordance with specification promises. In some cases, compatibility issues with early-release IEEE 802.11g hardware can be resolved through firmware upgrades.
Wireless Network Modes
Wireless networks work in one of two modes labeled as topologies: ad-hoc mode and infrastructure mode. The mode utilized depends on whether the objective is for computers to communicate directly with each other, or via a WAP.
In ad-hoc mode, data is sent to and from wireless network adapters connected to the computers. This eliminates the requirement to purchase a WAP. Throughput rates between two wireless network adapters are twice as fast compared to using a single network adapter connecting to a WAP. However, when a network is in ad-hoc mode it can’t link up to a wired network. An ad-hoc network is also referred to as a peer-to-peer network.
In infrastructure mode data between computers is delivered via a WAP. WAP allows connectivity to a wired network, affording expansion of a wired network with wireless capability. Wired and wirelessly networked computers can communicate with each other. WAP also lengthens the wireless network’s range as its placement between two wireless network adapters doubles their range. Routers and firewalls are also incorporated in some WAPs. The router provides shared Internet access between all your computers, and the firewall protects the network.
