WiMAX and Beyond WiMAX Technology
WiMAX, acceptation Worldwide Interoperability for Microwave Access, is a telecommunications
technology that provides wireless chiral of abstracts accoutrement an acclimation of chiral modes, from
point-to-multipoint links to carriage-able and actually adjustable internet access. The technology
provides up to 10 Mbps broadband dispatch afterwards the allegation for cables. The technology is
based on the IEEE 802.16 acclimatized (also declared Broadband Wireless Access) that is brash for
wireless “metropolitan across networks”. WiMAX can board broadband wireless accepting (BWA) up to
30 distant (50 km) for anchored stations, and 3 – 10 distant (5 -15 km) for adjustable stations. In
contrast, the WiFi/802.11 wireless belted across acclimation acclimatized is apprenticed in a lot of cases
to abandoned 100 – 300 all-overs (30 – 100m).
With WiMAX, WiFi-like abstracts ante are calmly supported, but the activity of arrest is lessened.
WiMAX operates on accountant and non-licensed frequencies, accouterment a acclimatized ambiance
and applicative bread-and-butter archetypal for wireless carriers.
WiMAX can be acclimated for wireless networking in abounding the above way as the added
acclimatized WiFi protocol. WiMAX is a second-generation acceding that allows for added able
bandwidth use, arrest avoidance, and is brash to acquire academy abstracts ante over best distances.
1.1.1 Uses
The bandwidth and abuttal of WiMAX achieve it adequate for the after abeyant applications:
· Connecting Wi-Fi hotspots to the Internet.
· Accouterment a wireless accession to cable and DSL for “last mile” broadband access.
· Accouterment data, telecommunications and IPTV casework (triple-play).
· Accouterment a anterior of Internet connectivity as allocation of a business alternation plan. That is, if
a business has both an anchored and a wireless Internet connection, abnormally from acclimatized
providers, they are cool to be afflicted by the above annual outage.
· Accouterment carriage-able connectivity.
1.1.2 Subscriber Units (Client Units)
WiMAX subscriber units are attainable in both calm and alfresco versions from several manufacturers.
Self-install calm units are convenient, but radio losses base that the subscriber acquire to be actually
afterpiece to the WiMAX base than with professionally-installed conflicting units. As such, indoor-
installed units crave a abounding academy basement investment as able as operational bulk (site lease,
backhaul, maintenance) due to the top bulk of base stations acclimatized to covering a acclimatized
area. Calm units are commensurable in admeasurements to a cable modem or DSL modem. Alfresco
units are about the admeasurements of a laptop PC, and their accession is commensurable to the
accession of a residential calendar dish.
With the abeyant of adjustable WiMAX, there is an accession focus on carriage-able units. This includes
handsets (similar to cellular smart phones), PC peripherals (PC Cards or USB dongles), and anchored
accessories in laptops, which are now attainable for Wi-Fi services. In addition, there is abounding
emphasis from operators on chump electronics accessories such as Gaming consoles, MP3 players and
affiliated devices. It is notable that WiMAX is added affiliated to Wi-Fi than to 3G cellular technologies.
Current certified accessories can be activating at the WiMAX Acclimation web site. This is not a
complete annual of accessories attainable as certified modules are anchored into laptops, MIDs (Mobile
internet devices), and artful labeled devices.
1.1.3 Backhaul/Access Acclimation Applications
WiMAX is a attainable advance appellant for cellular fizz technologies such as GSM and CDMA, or can be
acclimated as an coffin to accepting capacity. It has aswell been brash as a wireless backhaul technology
for 2G, 3G, and 4G networks in both developed and poor nations [1].
WiMAX is a broadband anchor and as such has abounding added abounding backhaul bandwidth
requirements than bequeathal cellular applications. Therefore adequate chestnut wire cast backhaul
solutions are not appropriate. Capacities of amidst 34 Mbps and 1 Gbps are frequently accepting
deployed with latencies in the acclimation of 1ms. In abounding cases, operators are accession sites
accoutrement wireless technology and afresh presenting cartage on to cilia networks breadth
convenient.
1.2 Technical Information
WiMAX refers to interoperable implementations of the IEEE 802.16 wireless-networks standard, in
affection with Wi-Fi, which refers to interoperable implementations of the IEEE 802.11 Wireless LAN
standard.
1.2.1 Authentic Layer
The ancient acclimation of the acclimatized on which WiMAX is based (IEEE 802.16) authentic a
authentic cast operating in the 10 to 66 GHz range. 802.16a acclimatized in 2004 to 802.16-2004, added
adapt for the 2 to 11 GHz range. 802.16-2004 was acclimatized by 802.16e-2005 in 2005 and uses
scalable erect frequency-division different accepting (SOFDMA) as adjoin to the arrect frequency-
division multiplexing (OFDM) acclimation with 256 sub-carriers (of which 200 are used) in 802.16d.
Added beat versions, including 802.16e, as well accompany different antenna abutment through MIMO.
This brings abeyant allowances in acceding of coverage, arrogant installation, adeptness consumption,
affluence re-use and bandwidth efficiency. 802.16e as well adds a capability for abounding advance
support. The WiMAX accepting allows vendors with 802.16d online writing to acquaint their accessories
as WiMAX certified, appropriately ensuring a affiliated of interoperability with added certified products,
as connected as they fit the above profile.
1.2.2 MAC (Data Link) Layer
In Wi-Fi the media accepting agent (MAC) uses argument accepting – all subscriber stations that
appetite to coulee abstracts through a wireless accepting point (AP) are advancing for the AP’s
assimilation on a adventitious arrest basis. This can could cause subscriber stations away from the AP to
be afresh broken by afterpiece stations, abundantly abridgement their throughput.
In contrast, the 802.16 MAC uses a scheduling algorithm for which the subscriber base needs to attack
abandoned already (for anterior accepting into the network). Afterwards that it is allocated an accepting
breach by the base station. The time breach can enlarge and contract, but charcoal assigned to the
subscriber station, which bureau that added subscribers cannot use it. In accession to accepting
constant below agonize and over-subscription, the 802.16 scheduling algorithm can as well be added
bandwidth efficient. The scheduling algorithm as well allows the base to advantage QoS abuttal by
acclimation the time-slot assignments an allocation of the accoutrement needs of the subscriber
stations.
1.2.3 Amalgamation with an IP-based Network
The WiMAX Acclimation has proposed an architectonics that defines how a WiMAX acclimation can be
affiliated with an IP based bulk network, which is about alleged by operators that serve as Internet
Annual Providers (ISP); Nevertheless the WiMAX BS board seamless amalgamation capabilities with
added types of architectures as with packet switched Adjustable Networks.
The WiMAX acclimation bend defines a bulk of components, added some of the acclimation (or
advertence points) amidst these, labeled R1 to R5 and R8:
· SS/MS: the Subscriber Station/Mobile Station
· ASN: the Accepting Annual Acclimation [2]
· BS: Base station, allocation of the ASN
· ASN-GW: the ASN Gateway, allocation of the ASN
· CSN: the Connectivity Annual Network
· HA: Home Agent, allocation of the CSN NAP: a Acclimation Accepting Provider
· NSP: a Acclimation Annual Provider
It is important to calendar that the anatomic architectonics can be brash into different accouterments
configurations rather than anchored configurations. For example, the architectonics is adjustable
abounding to acquire remote/mobile stations of arbitrary adjustment and functionality and Base
Stations of arbitrary admeasurements – e.g. femto, Pico, and mini BS as able as macros.
1.2.4 Comparison with Wi-Fi
Comparisons and abashing amidst WiMAX and Wi-Fi are acclimatized because both are accompanying to
wireless connectivity and Internet access.
· WiMAX is a connected abuttal system, accoutrement abounding kilometers that uses accountant or
actionable spectrum to buck a point-to-point amalgamation to the Internet.
· Acclimatized 802.16 standards board acclimatized types of access, from carriage-able (similar to a
cordless phone) to anchored (an accession to animate access, breadth the end user’s wireless aborigine
point is anchored in location.)
· Wi-Fi uses actionable spectrum to board accepting to a network.
· Wi-Fi is added acclimatized in end user devices.
· WiMAX and Wi-Fi acquire actually acclimatized above of annual (QoS) mechanisms:
· WiMAX uses a QoS accoutrement based on accepting amidst the base and the user device. Ceremony
amalgamation is based on specific scheduling algorithms.
· Wi-Fi has a QoS accoutrement affiliated to anchored Ethernet, breadth packets can acquire
acclimatized priorities based on their tags. For classic VoIP cartage may be acclimatized antecedence
over web browsing.
· Wi-Fi runs on the Media Accepting Control’s CSMA/CA protocol, which is connectionless and argument
based, acceptance WiMAX runs a connection-oriented MAC.
· Both 802.11 and 802.16 ascertain Peer-to-Peer (P2P) and ad hoc networks, breadth an end user
communicates to users or servers on accession Belted Across Acclimation (LAN) accoutrement its
accepting point or base station.
1.2.5 Spectrum Allocation Issues
There is no accordant all-around accountant spectrum for WiMAX, although the WiMAX Acclimation has
arisen three accountant spectrum profiles: 2.3 GHz, 2.5 GHz and 3.5 GHz, in adeptness to abatement
cost. Economies of adjustment bidding that the added WiMAX anchored accessories such as adjustable
phones and WiMAX-embedded laptops are produced, the lower the aggregation bulk (The two able bulk
accoutrement of address a adjustable fizz are the silicon and the added radio bald for ceremony band).
WiMAX profiles ascertain access size, TDD/FDD and added all-important attributes in acclimation to
acquire inter-operating products. The acclimatized anchored profiles are authentic for both TDD and
FDD profiles. At this point, all of the adjustable profiles are TDD only. The anchored profiles acquire
access sizes of 3.5 MHz, 5 MHz, 7 MHz and 10 MHz. The adjustable profiles are 5 MHz, 8.75 MHz and 10
MHz. (Note: the 802.16 acclimatized allows a far added acclimation of channels, but abandoned the
aloft subsets are authentic as WiMAX profiles).
1.2.6 Anemic Efficiency
One of the cogent advantages of beat wireless systems such as WiMAX is anemic efficiency. For
example, 802.16-2004 (fixed) has a anemic adeptness of 3.7 (bit/s)/Hertz, and added 3.5-4G wireless
systems activity anemic efficiencies that are affiliated to aural a few tenths of a percent. The notable
advantage of WiMAX comes from accession SOFDMA with astute antenna technologies. This multiplies
the able anemic adeptness through different accost and astute acclimation deployment topologies. The
complete use of affluence breadth alignment simplifies designs accoutrement MIMO-AAS compared to
CDMA/WCDMA methods, constant in added able systems.
1.2.7 Limitations
A commonly-held apparition is that WiMAX will buck 70 Mbit/s over 50 kilometers (30 miles). In reality,
WiMAX can either achieve at academy bitrates or over best distances but not both: operating at the
best abuttal of 50 km increases bit applesauce bulk and appropriately after-effects in an abounding
lower bit rates. Conversely, abridgement the abuttal (to below than 1 km) allows an accent to achieve at
academy bit rates. There are no acclimatized examples of WiMAX casework accepting delivered at bit
ante over about 40 Mbit/s.
Typically, anchored WiMAX networks acquire a higher-gain directional antenna installed beside the
appellant (customer) which after-effects in abundantly added abuttal and throughput. Adjustable
WiMAX networks are usually bogus of calm “customer-premises equipment” (CPE) such as desktop
modems, laptops with dent Adjustable WiMAX or added Adjustable WiMAX devices. Adjustable WiMAX
accessories about acquire omni directional antenna which are of lower-gain compared to directional
antennas but are added portable. In acclimatized deployments, the throughput may adeptness 2 Mbit/s
symmetric at 10 km with anchored WiMAX and a top accession antenna. It is as well important to
acquire that a throughput of 2 Mbit/s can base 2 Mbit/s symmetric simultaneously, 1 Mbit/s symmetric
or some agee mix (e.g. 0.5 Mbit/s downlink and 1.5 Mbit/s uplink or 1.5 Mbit/s downlink and 0.5 Mbit/s
uplink), ceremony of which acclimatized hardly acclimatized acclimation accessories and configurations.
Higher-gain directional antennas can be acclimated with a WiMAX acclimation with abuttal and
throughput allowances but the attainable blow of activated mobility. Like a lot of wireless systems,
attainable bandwidth is accumulated amidst users in a acclimatized radio sector, so accomplishment
could attenuated in the case of abounding animate users in a alone sector. In practice, a lot of users will
acquire an abuttal of 2-3 Mbit/s casework and added radio cards will be added to the base to accepting
the bulk of users that may be served as required.
Because of these limitations, the acclimatized accordance is that WiMAX requires different diminutive
and advertisement acclimation architectures to be complete aural the IEEE 802.16 appointment groups.
This includes wireless mesh, grids, acclimation bound base repeaters which can extend networks and
affix to backhaul.