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competitors WIFI

V. STANDARDS COMPETING

A. RETAIL STANDARDS TO WIFI COMPETITORS

1. HOME RF

General:
Launched in March 1998 the Home Radio Frequency Working Group (HomeRF WG) consisting of Compaq, HP, IBM, Intel and Microsoft, has developed a protocol SWAP (Shared Wireless Access Protocol) for transporting voice and data through a wireless technology for domestic use, for a throughput of 1.6 Mbps to 20 Mbps SWAP operates a network with three types of units, a control point, a unit for voice (isochronous mode), a unit for data (asynchronously). The SWAP protocol works both peer to peer mode for exchanging data in client server mode for voice transfer.
Home RF Networks are secured by a security algorithm, key of 58 bits.
Layer 2:
The MAC layer uses a protocol TDMA (Time Division Multiple Access), time division multiplexing protocol for the transport of voice and a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) for the data.

Conclusion:

This standard has never been established in Europe, and the emergence of 802.11b has accentuated the decline.

2. HIPERLAN HIPERLAN

· 1

ETSI has developed Hiperlan 1 (1996) and HIPERLAN 2 (1999), to compete with the U.S. standard 802.11. This standard operates in the frequency band of 5.15 to 5.30 GHz and has a throughput of 23.5 Mbit / s for an average range of about 50 meters for the more powerful equipment. The architecture of Hiperlan type 1 is decentralized, there is no notion of access point, cons by a node can operate in bridge. Key features of HiperLan1:

-A multiple access system with priorities called EY-NPMA (Elimination Yield Non-Preemptive Multiple Access). Mixture of carrier detection of CSMA and reporting of assets to manage five priority priority levels. It is to scan the channels in order of priority until a free channel to transmit. Level 2 of the OSI model is divided into two sublayers, the sublayer CAC (Channel Access Control) which corresponds to the physical part of the access technology (management problems related to wireless channel and the entire transmission and reception) and the MAC sublayer corresponds to the logic or the formatting of the frame, the internal routing, algorithms for confidentiality, management of priority (QoS) and insertion and removal stations.

-A technique for frame relay network to extend room in which the extension is beyond the radio range. For this standard distinguishes between two types of nodes, relay nodes (forwaders) for receiving packets (which are not their intended) for relay to a final destination, and simple knots (not forwaders). For this, the frame has a pair of traditional MAC address but also another pair, denoting the intermediate nodes and forming part of encapsulation CAC (Channel Access Control).
This technique is based on an algorithm to automatically build the network topology. The architecture of this network grows through the frames of type "Hello", allowing a node to know its close proximity, and topology control frames, so the routing table, distributed throughout the network.

· HIPERLAN 2

Founded in 1999 by various companies (Bosch, Dell, Ericsson ...) the H2GF (Hiperlan 2 Global Forum) supports the project HiperLAN 2.
This standard is in direct competition with 802.11a, it operates on the 5GHz band in OFDM (see 802.11) with a flow rate of 54Mbit / s. Its architecture is a centralized type mode called the access network-like infrastructure mode Wi-Fi, where each terminal is connected to an access point. And type architecture Ad-Hoc, but when a station called Central Control (CC) becomes the access point.

Above Hiperlan2 this architecture works in two modes:

-centralized mode: All packets pass through the access point.

-mode: two terminals can communicate directly without an AP or a CC.

Features:-
Broadband: the physical layer can transmit and receive data at 54 Mbps OFDM modulation through.

-Mode Connection-oriented: before each shipment, a connection is established between the stations and AP (access point). Communications point-to-point communications are bidirectional and point-to-multipoint connections are unidirectional. A broadcast channel can reach all stations simultaneously.

-QoS: the fact that communications are connected mode, the QoS is easily implementable. QoS and broadband offers the possibility of channeling all types of data, video data.

-Automatic allocation of frequency radio channels used are automatically selected by the access point depending on interference in the environment and the frequencies used by other radio cells that surround it.

-Security : The standard supports authentication and data encryption.

-Mobility: The terminal receives the data access point the best location in relation to him, that is to say that the radio signal is more intelligible. The cell change (roaming) is done automatically.
-Independence-à-vis the network: the protocol stack Hiperlan 2 is flexible and adapts easily to all types of networks and applications.

- Power saver: the standard defines the minimum power state and a standby mode.

The general architecture is composed of three layers:
° CL: Convergence Layer (Layer Convergence). It is used to interface different types of conventional networks (cell types ATM packets to Ethernet, TCP / IP or UMTS) adapting the services requested by upper layers to the services offered by the DLC layer.
· DLC: Data Link Control (data link control layer): a first sub-layer is divided into two parts.
-RLC (Radio Link Control) protocol that manages all aspects of control connections through three subgroups. ACF manages associations and disassociation, as well as encryption; DRR allows the automatic selection of the best frequencies and power and manages the handover, ACS handles the connection control.
-EC (error checking) which monitors the data and thus increase the reliability of the connection.

Conclusion: Despite
elaborate design and superior functionality to Wi-fi HIPERLAN are not marketed. The HIPERLAN 1 does not exceed the prototype stage. As for HiperLAN 2, its design is in direct competition with 802.11a and has little chance to develop one day.

3. BLUETOOTH

The Bluetooth standard has been set up by the Working Group, Bluetooth SIG (Special Interest Group). Formed from large computer manufacturers such as Nokia, Ericsson, IBM or Intel, it has grown today to more than 2,500 companies. In parallel the American Institute IEEE product specifications and developments of the Bluetooth standard through a Working Group: IEEE 802.15. This group is divided into four distinct groups: 802.15.1 (the link between Bluetooth and 802), 802.15.2 (WPAN and WLAN coexistence), 802.15.3 (WPAN high rate = 20 Mbps), 802.15.4 (WPAN Low Rate = 200 Kbps).
This standard is not, strictly speaking, in competition with the wifi, because it applies only to networks type short-range WPAN with average speeds and at low cost. This technology works on 2.4 GHz ISM band with a technique for fast frequency hopping (FHSS Spread Spectrum Frequency Hope, which I describe later, at 1600 hops / s) and phase modulation GFSK.

Note: the number of channels is limited to 23 in France, Spain and Japan instead of 79 as the U.S. (in case of compatibility problems it is necessary to master the French from the U.S.) .

The standard defines three classes of devices based on transmission power: power Power Class
Maximum Output Power Control Range
a 100mW (20dBm) 100 m * Mandatory between 4 dBm to Pmax
2 ** 2.5mW (4dBm) Not Defined Optional
March 1 mW (0dBm) 10 m * Optional * must
that these distances are distances measured in free field, ie without obstacles between the transmitter and receiver. Space disturbed (eg by walls), litters are smaller (100m becomes about 30 to 40 m and 10 m can be 4m).
** this class is very little, if any, used for now.

Architecture The architecture is centralized type: cell Basic Bluetooth is more than eight knots, with a master station and slave stations. The master station distributing access rights to its slave stations. Two types of architecture have been defined: piconet and scatternet.

· Piconet: the simplest architecture, a master node can manage seven slave nodes (8 units maximum, 3 voice communications at a maximum, 7 data communications at maximum). All communications go through the master station and is with the same frequency hopping sequence.

· Scatternet: architecture for the association of several piconets.Une slave station can be associated with two piconets, and a slave node can become the master node to another piconet. Operation

These piconets are established dynamically and automatically as Bluetooth devices enter and leave the radio range, users not having to worry about contingencies matérielles.La Transmission is a diagram or precut "slott" Each time slot has a duration of 625μs. The master will transmit on equal time slots, starting at the beginning of time slot, and the slave responding to the odd time slot. Thus the "full duplex" via Bluetooth. Each packet is transmitted on a frequency hopping. This means that the frequency will remain the same for each packet. Looking more closely, the 1600 leap second, effectively means that each "hop" is in operation for 625 microseconds (1 / 1600). By cons, if the package is too large, the transmission can last for up to five slots. This is to prevent information loss of package by changing the frequency.
A Bluetooth device operates in transmit and receive alternately, or TDD (Time Division Duplex). The master leads by a polling slaves.

types of communications:
Within a piconet can coexist several types of communications:

· Channel asynchronous data of two types: a link
-symmetric 432.6Kbits / s
-linked asymmetric maximum throughput of 721 kbps in either direction with a speed 57.6 kb / s for the return channel.

· Channel phonies of synchronous and simultaneous:
-link 64Kbit / s synchronous.

· a link with simultaneous asynchronous data and synchronous voice communications.

types of links:

· SCO (Synchronous Connection Oriented): used for circuit mode communication with properties of QOS (Quality Of Service) and for reservations of slots at regular intervals.

· ACL (Asynchronous Connection Less): used for asynchronous communication. The ACL link is sent between the slots assigned to the SCO data. This allows the master to communicate with any device during this time. The teacher then uses a connection in packet switching to communicate with all devices in the piconet.

Packets:

code accès72 tête54-bit bit bit Données0

-2745 Access code: allows synchronization between Bluetooth components.

Header:
@ MAC3 Type4 bit bit bit Flux1 DT ** SN * 1 bit 1 bit HEC (Header Error Control) 8-bit
* DT: transmission request
** SN: Sequence Number
type indicates the type of packets, there 16 types of packets defined in three groups: control packets, asynchronous data packets, DM (Data Medium), DH (Data High) synchronous data packets, DV (Data Voice), HV (High quality Voice).

Conclusion:
Bluetooth and WiFi are not in direct competition. These two technologies are actually really different uses and could both bring something to the wireless market. The only major obstacle is that operate in the same frequency band. Interferences occur when Bluetooth and 802.11 transmit simultaneously. Bluetooth does not use carrier sensing, this causes a destruction of the bits of information (collision), requiring the system to retransmit entire packets of data. The Bluetooth SIG and the 802.15 working group are responsible for identifying solutions (rather than soft material) to these two technologies coexist. Others share the future of Bluetooth in its niche "low-speed, short range" no longer seems assured. New manufacturers are developing competing technologies:

4. 802.15.3

This new IEEE standard published in August 2003 by the 802.15 working group, was designed for transferring audio or video file requiring broadband. This standard defines a rate of 55Mbits / s over a range of 100 meters, broadcast on the frequency of 2.4 GHz and guarantees no interference with the standards of types 802.11x, 802.15x, and Bluetooth.
addition it includes the TDMA protocol for managing concurrent connections and the AES encryption algorithm for a high level of security.

5. 802.15.3a (UWB: Ultra Wide Band)

Latest standard in preparation taken from a military technology used in the field of radar GPR (Ground Radar Penetring) able to detect elements through all kinds of materials (water, earth, concrete ...). Unlike conventional wireless technology that sends a signal over a narrow bandwidth, UWB sends millions of short signals on a low-power ultra-wide frequency spectrum. The main advantages are: very high speed (110 to 480 Mbps), low consumption, no constraint topology (the waves pass through walls), difficulties of intercepting waves (short transmission time and change frequency).
By cons, as UWB uses a very broad spectrum of frequencies, regulators fear a disruption of existing communication channels. United States, after three years of testing, the FCC gave its approval for the sale of UWB systems for certain applications including wireless transmission inside buildings.
Many manufacturers see this technology replacing all others.

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