So Which One is It Now

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Hello readers, we are coming to a close on this 60 Ghz band soon . In my previous posts, we have been seeing about the technology introduced in this 60 Ghz band by IEEE 802.11 ad – beamforming training associated with the 802.11 ad and the enhancement that has been made to  connect with the PCP/AP without preceding coordination. In this post we will see about what various organization has to contribute to this 60 Ghz band and then which organization hold strong position with respect to the standardization of this frequency band.

COMPARITIVE ANALYSIS:

BEAMFORMING: 

We have already seen about the beamforming of the IEEE 802.11 ad, so lets see about the rest.

  • The ECMA-387 uses special frames called TRN frames to determine the appropriate antenna weight vectors. The beam forming training are done by open loop and closed loop training. In closed loop training, transmit antenna derives its weight vectors based on feedback provided by receive antenna, but in open loop there is no such thing as feedback and same training weights are used during both transmission and reception.
  • IEEE 802.15.3c provides three level training mechanism using beam codebooks [1] such as best QO pattern training, best sector level training and beam pair training. It used special training frames which is the main difference between this and 802.11 ad protocol.

802.11 ad training is called in-packet training as it used data frames and not special frames, while the rest of the two are called Out packet training.

NETWORK ARCHITECHTURE:

  • ECMA – 387 uses completely distributed architecture without any controller if Type – A devices are only present in the network and if Type -B devices are also present then TYPE-A acts as a coordinator and it operated on master-slave basis. Type-A devices is expected to support high data rates (upto 6.35 Ghz) and TYPE – B devices are rather simple, low power devices (upto 3.175 Ghz).
  • IEEE 802.15.3c proposes completely centralized network architecture in which PNC coordinates communications among device pairs.
  • IEEE 802.11 ad PBSS is centrally coordinated by PCP/AP.

MAC Layer :

  • ECMA – 387 uses distributed MAC mechanism in which after device discovery is done, the data tranmission takes place without intervention of any coordinator.
  • IEEE 802.15.3 c provides hybrid channel access mechanism which are based on CSMA/CA or TDMA based channel  access in CAP and CTAP durations respectively. The reservation of TDMA slots are done using CAP periods.
  • IEEE 802.11 ad used the same hybrid channel but the channel access is done using polling by PCP/AP during ATI period.

Comparison of Standards based on [2].
Comparison of Standards based on [2].
The table aboves compares various parameters definition as proposed on the three standards. I have tried to explain in detail about the three main differences between the three standards. More about the comparison can be seen on [2].

The next post will be the final concluding post about the winner of the 60 Ghz band and the future scope of this ultra fast technology which is set to dominate the world in few years.

Regards,

Manigandan Siva.

 

REFERENCES:

[1]. J. Wang, Z. Lan, C. woo Pyo, T. Baykas, C.-S. Sum, M. Rahman, J. Gao, R. Funada, F. Kojima, H. Harada, and S. Kato, “Beam codebook based beamforming protocol for multi-gbps millimeter-wave wpan systems,” Selected Areas in Communications, IEEE Journal on, vol. 27, no. 8, pp. 1390–1399, October 2009.

[2] Kishor Chandra  , Arjan Doff , Zizheng Cao  , R. Venkatesha Prasad  , Ignas Niemegeers , “60 Ghz MAC standardization: Progress and way forward”,  Consumer Communications and Networking Conference (CCNC), 2015, IEEE, Jan. 2015 arXiv:1502.00507 [cs.NI]..