IEEE 802.16 Standard

A description about IEEE 802.16 Standard based on the text book "Ad Hoc Wireless Networks: Architectures and Protocols" by C. Siva Ram Murthy and B. S. Manoj.

1. IEEE 802.16 STANDARD
Lakshmi. M. B
Sr. No. 9219708
S3, MTech CSE
Sahrdaya College of Engineering and Technology, Kodakara
September 29, 2020
Lakshmi. M. B IEEE 802.16 Standard 1/25

2. Metropolitan Area Network (MAN)
INetworks that span several kilometers.
IMuch larger in size than LANs.
ITheir functionalities dier from those of LANs.
IOften connect large buildings.
IUsage ofbroadband wireless access (BWA)led to the
requirement of a standard.
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3. IEEE 802.16 Standard
IOcially known asair interface for xed broadband
wireless access systems.
IBased on OSI model.
ISpecies the air interface of xed point-to-multipoint BWA
systems.
IDLL is capable of supporting multiple physical layer
specications.
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4. IBSs are connected to public networks.
IBS serves several SSs, which in turn serve buildings.
IThus, BS provides SS with a last-mile (or rst-mile) access to
public networks.
IBSs and SSs are stationary.
IChallenge { to provide support for multiple services with
dierent QoS requirements and priorities.
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5. Dierences Between IEEE 802.11 and IEEE 802.16
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6. IEEE 802.16 Protocol Stack
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7. Physical Layer
IUses traditional narrow-band radio (10-66 GHz) with
conventional modulation schemes for transmission.
IConvergence sublayer hides the transmission technology from
the DLL.
I2 new protocols are added at the physical layer { IEEE
802.16a and IEEE 802.16b
IIEEE 802.16aoperates at 2-11 GHz frequency range.
IIEEE 802.16boperates at 5 GHz ISM band.
Lakshmi. M. B IEEE 802.16 Standard 7/25

8. ISignal strength of millimeter waves falls o with distance from
BS resulting in reduction of SNR.
I3 modulation schemes are used, namely,
1.
2.
3.
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9. 1.QAM-64
IOers 6 bits/baud data rate.
IUsed by subscribers that are located near BS.
2.QAM-16
IOers 4 bits/baud data rate.
IUsed by subscribers that are located at intermediate distance
from BS.
3.QPSK
IOers 2 bits/baud data rate.
IUsed by subscribers that are located far away from BS.
Lakshmi. M. B IEEE 802.16 Standard 9/25

10. IAssume 30 MHz of spectrum.
ISubscribers that are far away get lower data rates.
IMillimeter waves travel in straight lines unlike microwaves.
IHigh error rates associated with millimeter waves have called
for the usage of Hamming codes.
IOther networks uses checksums to detect errors and request
transmission of frames that have errors.
Lakshmi. M. B IEEE 802.16 Standard 10/25

11. IPhysical layer can pack multiple MAC frames in a single
physical transmission to gain improved spectral eciency.
IVoice trac is generally symmetric whereas Internet access
have more downstream trac than upstream trac.
ITo accommodate them, IEEE 802.16 uses FDD and TDD.
IBandwidth can be changed dynamically to match the trac in
the corresponding direction.
Lakshmi. M. B IEEE 802.16 Standard 11/25

12. Data Link Layer
IDesigned for wireless environment.
IBroadband services call for very high uplink and downlink bit
rates, and a range of QoS requirements.
IPreferred to be a protocol-independent engine.
IDLL of IEEE 802.16 was designed to meet all these
requirements.
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13. ISubdivided into three sublayers:
1.
2.
3.
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14. 1. Security Sublayer
IBottom-most sublayer.
IDeals with privacy and security.
ICrucial for public outdoor networks.
IManages encryption, decryption, and key management.
Lakshmi. M. B IEEE 802.16 Standard 14/25

15. 2. MAC sublayer common part
IProtocol-independent core.
IMAC frames are integral multiples of physical layer time slots.
IEach frame contains downstream and upstream maps.
IStrikes a trade-o between stability of contention-less
operation and eciency of contention-based operation.
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16. IDownlink { data to SS is multiplexed using TDM.
IUplink { medium is shared by SS using TDMA.
IAll services oered by IEEE 802.16 are connection-oriented.
I4 classes of service:
0.1
0.2
0.3
0.4
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17. (i) Constant bit rate service
IIntended for transmitting uncompressed voice.
ICertain time slots are dedicated to each connection of this
type.
IAvailable automatically without explicit request.
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18. (ii) Real-time variable bit rate service
IIntended for compressed multimedia and soft real-time
applications.
ITo accommodate them, BS polls SS periodically.
ICategory of real-time trac| where the missing of
deadlines results in non-catastrophic events.
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19. (iii) Non-real-time variable bit rate service
IIntended for large le transfers and other transmissions that
are not real-time.
ITo accommodate them, BS polls SS often.
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20. (iv) Best eort service
IIntended for all other applications.
IPolling is absent and SS contend by sending requests for
bandwidth in time slots marked in the upstream map .
ICollisions are reduced by using the binary exponential back-o
algorithm.
Lakshmi. M. B IEEE 802.16 Standard 20/25

21. 3. Server specic convergence sublayer
ITopmost sublayer.
IFunction { to interface to the Network layer.
IIEEE 802.16 - designed to integrate seamlessly with both
connection-less protocols and connection-oriented protocols.
IMapping ATM connections to IEEE 802.16 is quite
straightforward.
IMapping packets to IEEE 802.16 is done in a judicious
manner.
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22. IRequest/grant scheme is used for handling bandwidth
allocation.
IBandwidth requests are always per connection.
IBandwidth grants may begrants per connection (GPC)or
grants per SS (GPSS).
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23. Bandwidth GPSS
ISuitable if there are many connections per SS.
IOoads the responsibilities of the BS.
IAllows sophisticated QoS guarantees and a low overhead.
INeeds complex SSs.
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24. Bandwidth GPC
Isuitable if there are only a few users per SS.
IBS grants bandwidth to each connection.
IIncurs a higher overhead.
IAllows a simpler SS.
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25. Lakshmi. M. B IEEE 802.16 Standard 25/25