Which is better Wifi vs WiMax

IEEE 802.16 / WiMAX

The IEEE 802.16 (BWA, Broadband Wireless Access) standard describes a wireless broadband technology for a wireless Metropolitan Area Network (MAN) that was developed in parallel to IEEE 802.11 for a wireless LAN.
At ETSI (European Telecommunications Standards Institute) the corresponding standard is known under the name WiMAX (pronounced: waimäx) or Hiper-MAN. In common parlance, the term WiMAX (Worldwide Interoperability for Microwave Access) is used.
WiMAX offers the possibility of building broadband access networks via radio without a complex wired infrastructure. This means that WiMAX is seen as an alternative to fixed line DSL. Sometimes it is also referred to as wireless DSL (W-DSL).
The diameter of the coverage area of ​​a WiMAX base station is comparable to that in cellular networks. A range of several kilometers reduces the last mile between the network operator and the customer. WiMAX is therefore an alternative, especially in areas where DSL or cable cannot provide Internet access.

WiMAX with mobile use is as complex as GSM or UMTS, for example. For WiMAX everything has to be redeveloped that is already available for cellular networks.
One problem, for example, is the mutual authentication of the network and the end device. Or rather, the billing of the service. You can only bill the access (flat rate), but not the time or the volume. If so, then the complexity increases. Overall, the development and installation costs are very high, which makes the operation of WiMAX less interesting in countries with an extensive cellular network such as GSM, UMTS or LTE.

Properties and requirements

  • In the indoor area, the reception quality can vary depending on the location.
  • In many cases, a window antenna is necessary for optimal reception.
  • Like WLAN and UMTS, WiMAX has the same problems in terms of shadowing (dead spots).
  • If the radio connection is optimal, up to 3 Mbit / s can be transmitted.

WiMAX standardization

The first standardization in 2001 specified the radio interface for the radio relay frequencies between 10 and 66 MHz. This technology should achieve a range of 50 kilometers at a transmission rate of 70 Mbit. Of course only in the ideal case, with a direct line of sight and with stationary receivers. Later, interest shifted to the frequency range between 2 and 11 GHz with no line of sight between the base station and receiver. In 2003 the sub-standards 802.16a and 802.16REVd were passed. Both standards were then revised in 2004 and combined in July 2004 as 802.16d-2004 or "WiMAX fixed".
In subgroup 802.16e, work was carried out on an extension that works for mobile applications at low speeds in the license-free and license-free frequency spectrum below 6 GHz. This standard is called "Wimax mobile".
Independently of the IEEE and the WiMAX forum, South Korea has taken its own steps at the same time as a project called WiBro (Wireless Broadband). In 2004, South Korea agreed to participate in the IEEE standardization. WiBro was therefore only included in the standard under 802.16e.
Because of the many different types of access methods to the radio interface, the compatibility within the standard is at risk. The danger for WiMAX is hardware that is not compatible with each other. This makes it more difficult for network operators to decide which hardware to invest in with which standard.

descriptionIEEE 802.16 IEEE 802.16a
IEEE 802.16d (WiMAX)
IEEE 802.16e (WiMAX) IEEE 802.16m (WiMAX 2)
standardizationDecember 2001 January 2003 to July 2004 December 2005 ?
Frequency band10 to 66 GHz 2 to 11 GHz 0.7 to 6 GHz  
Bandwidths20, 25 and 28 MHz scalable from 1.5 to 20 MHz  
max. data rateup to 134 Mbit / s (28 MHz channel)up to 75 Mbit / s (20 MHz channel) up to 15 Mbit / s (5 MHz channel) up to 120 Mbit / s
max.range up to 75 km up to 5 km with indoor antenna
up to 15 km with external antenna
maximum 50 km
up to 5 km
typically up to 1.5 km
maximum 30 km
modulationQPSK, 16QAM, 64QAM OFDM256, OFDMA, 64QAM, 16QAM, QPSK, BPSK OFDM256, OFDMA, 64QAM, 16QAM, QPSK, BPSK  
receiverfirmlyfixed with external antenna for indoor use, restricted mobility nomadic use (not comparable to mobile communications) nomadic use (not comparable to mobile communications)

Frequencies

WiMAX uses the frequency bands between 2 and 11 GHz. This means that WiMAX can be used worldwide. Programmable DSPs offer the necessary flexibility to be able to set country-specific frequencies, emissions and services without having to develop a new product for each country.

regionFrequency ranges *
Europe3,5 / 5,8
Russia3,5 / 5,8
Middle East3,5 / 5,8
Africa3,5 / 5,8
Asia / Pacific2,3 / 2,5 / 3,3 / 3,5 / 5,8
Canada2,3 / 2,5 / 3,5 / 5,8
United States2,5 / 5,8
Central / South America2,5 / 3,5 / 5,8

* The frequency ranges may be released differently in the individual countries in the region.

architecture

The 802.16 standards are not as extensive as, for example, GSM or UMTS. Many areas, especially at the management level, are not included. In this way, WiMAX networks can be integrated into different infrastructures and management environments. However, the implementation requires network operators with mobile communications experience.

The architecture of 802.16 provides base stations (BS) and several remote subscriber stations (SS). The subscriber stations are the transmitting and receiving devices that are at the customer's premises. In simple terms, the subscriber stations are the WiMAX modems. They are coordinated by the base stations. A base station serves several subscriber stations. So that the SS are as small and inexpensive as possible, there is a lot of functionality and intelligence in the base stations.
The air interface R1 describes the access control of the terminals and the base stations. The radio connection is encrypted. AES with 128-bit keys is used as the encryption method. The WiMAX remote stations configure themselves independently and exchange the keys again at regular intervals. Eavesdropping is almost impossible.
Central access control enables quality-oriented transmission in the sense of Quality of Service (QoS). Communication with the core network is handled via IPsec.

Stationary connections according to the IEEE 802.16d standard are comparable to installing a satellite dish. The WiMAX end device must be set up as elevated as possible or have an external antenna. Line of sight from the participant to the station would be ideal. But both increase the installation effort. The mobile standard "WiMAX mobile" (IEEE 802.16e) is therefore preferred.
A typical WiMAX modem consists of a radio modem, a router and a small VoIP telephone system. Ideally, installation is limited to unpacking and connecting. With modern devices, the configuration is fully automatic as with DSL with TR-069.

Transmission speed and range

Theoretically, WiMAX can bridge up to 50 kilometers. In practice, however, the technology only extends a few kilometers. The cell radius is limited as the speed decreases with distance. WiMAX supports variable channel bandwidths from 1.25 MHz to 20 MHz and a transmission speed of up to 75 Mbit / s. The frequency planning in Germany provides for 3 radio channels with 7 MHz. 1 to 22 Mbit / s are possible in each channel. In practice there will hardly be more than 10 Mbit / s. Typical user data rates are between one and six Mbit / s.

Transmission technology

The following techniques are used for WiMAX to improve signal reception:

The physical layer (bit transmission layer) provides for the use of OFD Multiple Access (OFDMA). This results in an effective channel distribution of the frequency spectrum. Then each channel is processed with a further coding process. With Scalable OFDMA (SOFDMA), the sub-channels can be processed with different modulation methods (QPSK, 16QAM, 64QAM) depending on their quality.

Guarantee of quality of service

  • dynamic frequency selection (DFS)
  • Regulation of the output power (Automatic Power Control, APC)
  • Channel coding according to Forward Error Control (FEC) with Reed-Solomon to reduce the bit error rate
  • Request for acknowledgments of receipt (Automatic Retransmission Request, ARQ)
  • Connection orientation on the data link layer (Grant Request Protocol and Differentiated Services, DiffServe)

Frequency allocation in Germany

As part of the auction of UMTS licenses for the use of a reserved frequency spectrum, licenses for the use of point-to-point directional radio (PmP-RiFu) called Wireless Local Loop (WLL) were also auctioned. More than 50 companies took part and endeavored to build an infrastructure based on radio relay for fast Internet access and site networking. A short time later, almost all providers disappeared again without a realistic product ever coming onto the market. The business models turned out to be not economical.
In the meantime, technical advances have been made and with WiMAX a more flexible radio technology has been developed, which is also defined as a standard.
The Federal Network Agency (BNETZA) is responsible for frequency allocation in Germany. The tender for WiMAX frequencies between 3.4 and 3.6 GHz ran in Germany until the end of February 2006. 4 to 5 providers were expected per region. But around 900 applications have been received by the Federal Network Agency. Because the demand was too great, the frequencies were auctioned off in December 2006. The procedure for UMTS frequencies was similar.

The total amount from the WiMAX frequency auction is EUR 56.066 million. Up for auction were 4 frequency packages in the range from 3.4 to 3.6 GHz for 28 regions in Germany. In the frequency auction, 3 providers bought nationwide frequencies.

  • Clearwire Europe S.á.r.l. (Luxembourg, US company): nationwide frequency package A (28 regions)
  • Inquam Broadband GmbH (startup from Cologne): nationwide frequency package B (28 regions)
  • DBD - German broadband services GmbH (Heidelberg): Frequency package C (without region 14) and region 14 from frequency package D

Televersa Online and MGM Productions Group (from Italy) have acquired frequencies for three Bavarian regions and Munich.

  • Televerse Online GmbH: Region 25 and 28 from the frequency package D
  • MGM Productions Group S.R.L. (Italy): Region 27 from the frequency package D

The three frequency owners operating across Germany can be expected to strive for rapid network development. By the end of 2009, 15 percent of the municipalities in each supply area must be covered, and by the end of 2011 even 25 percent. A nationwide network requires around 10,000 base stations. It is estimated that the construction will cost 500 million euros. Annual operation is estimated at 160 million euros.
Some of the auctioneers are characterized by the fact that they already have WiMAX or WLL networks in operation and market them commercially. Experience from Austria shows that the WiMAX business can be operated successfully.
The DBD company wants to supply all 28 regions with broadband radio by 2012. With the shareholders Intel and Merril Lynch, around 1 billion euros are being invested in a nationwide WiMAX network. At the end of 2006, DBD was already operating over 30 radio networks. Partly in the city, partly in rural areas.
The radio providers not only compete with each other, but also against the mobile radio operators with UMTS and HSDPA, as well as the DSL provider. Since the frequency bands only have a transport capacity of 21 MHz, the WiMAX networks will not be suitable for the mass market. The WiMAX providers will by far not be able to offer as many broadband connections as the DSL providers can. However, it is to be expected that the WiMAX offers will be a hit especially in rural regions, because broadband offers are rare there.

Market development


After the first enthusiastic reports and activities, things have become very quiet in Germany around WiMAX. With a few exceptions, the license holders have not taken action. Clearwire did not act at all. Televersa has returned its WiMAX license. And the other providers were hardly noticed.

One can say that WiMAX is suitable for use in rural underdeveloped regions such as Russia, Asia and Africa. Only countries with few wired networks were particularly interested in WiMAX. Including countries in the Asian region. For example India, Pakistan and China. But also Russia and large parts of Africa.
The technique sounded tempting. 50 km radius of the radio cells, nomadic use and integrable modems. Like WLAN, but with a much greater range. But the reality was very different. A far shorter range than promised, high demands on the installation at the user (often an external antenna is required), low transmission speed, few hardware providers and thus expensive technology.
At the same time, the development of WiMAX has put the 3GPP under considerable pressure. Which is why LTE has now become the standard that has become the fourth generation of mobile communications worldwide. LTE is cheaper on the network side as well as on the end devices. At the same time, a lot of development resources are invested in further development. The choice of end devices is much larger and global interoperability is better.

WiMAX became superfluous with the global introduction of LTE and may only play a regional role in a few countries. The technology is considered dead. There will be no further developments.

Overview: WiMAX technology

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