Subject: [6gip] continueing the discussion on B5G

From: <[email-masked]>
Date: Tue, 1 Dec 2020 15:55:42 +0000

Dear all enthusiasts,
FWIW the current comsoc mag includes a bunch of interesting papers and vies on B5G features and technologies - please see the overview provided in e.g. https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269502 on Multi-layer Wireless Network Architecture or https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269507 on THz frequency bands for wireless transmissions to provide ubiquitous high-speed Internet access beyond 5G.
Any ideas which of the mentioned aspects could serve as topic for discussion here?
Thanks and best regards
Dirk

---

From: Alexandre Petrescu <[email-masked]>
Date: Thu, 3 Dec 2020 12:32:47 +0100

Le 01/12/2020 à 16:55, [email-masked] a écrit :
> Dear all enthusiasts, FWIW the current comsoc mag includes a bunch of
> interesting papers and vies on B5G features and technologies - please
> see the overview provided in e.g.
> https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269502 
> <https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269502> on
> Multi-layer Wireless Network Architecture or 
> https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269507 
> <https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9269507> on
> THz frequency bands for wireless transmissions to provide ubiquitous
>  high-speed Internet access beyond 5G. Any ideas which of the
> mentioned aspects could serve as topic for discussion here? Thanks
> and best regards Dirk
> 

Thanks for pointing to this issue of the IEEE Communications magazine.
Some articles feature topics about THz, Beyond 5G and 6G.

I have read the overview and editorial articles you point to, all while
pondering over the IP question.  With that in mind, I got interested in
the article entitled "Toward End-to-End, Full-Stack 6G Terahertz
Networks" https://ieeexplore.ieee.org/document/9269934/

That paper treats much about PHY, MAC and Transport layers (e.g. UDP,
QUIC and maybe evolutions of TCP for the enormous bandwidth afforded by
the use of wide bands in the THz ranges).  But unfortunately there is
nothing about IP in it.  I would have expected they would see a similar
'6' in IPv6 and 6G, but no.

That said, I dare to take some of the expectations of 6G described in
these papers and formulate questions about IP.

         What is the impact of the 6G THz to IP protocols?

1. THz range means more directional propagation than GHz range, but also
more loss, interference, and hence shorter ranges and hence more power
needed to power the base stations to send data (the energy deserves
being mentioned first, actually).  Some way to deal with loss,
directionality and range is the use of multiple simultaneous beams.

Maybe there will be multiple ppp links between a 6G base station and a
6G terminal (as opposed to currently just one ppp link)?  Will these ppp
links be somehow aggregated?  Will a ppp link have 4, 6, 8... direct
neighbors, rather than currently just 2?

The cells will be smaller - will there be more frequent IP handovers
than today?  Currently an IP handover happens when moving from one SGSN
to another; that is across an area of maybe hundreds of kilometers.
It's a very rare event, only some cars must deal with it.  Typical end
users dont travel that far while still talking on the phone.  Maybe in
6G there will be IP handovers after only tens of kilometers (not
hundreds), at which point some users might be concerned about loss of IP
sessions upon handovers.

2. the wider widths of band afforded in the unexplored spectrum at THz
range will offer higher bandwidth.  But what does it mean to IP?  The IP
protocol, intuitively, is not influenced from low or high bandwidth.
There is no field in IP headers that deal with bandwidth or other time
constraints.  IP runs the same on high speed or low speed links, in
principle.

However, a higher bandwidth might give much resources to the MAC layer
designers.  For example, when WiFi bandwidths were very low the MAC
protocol exchanges were very brief (2 or 4 messages).  Then, with the
arrival of 802.11g the MAC protocol added new features like
authentication, so the message exchanges grew more (6 and more).  The
beacons were no longer expensive, so there were more beacons.

In that sense, may be more features from IP layer might be moved into
MAC layer.  Maybe more security protocols from IP (IPsec) could be moved
down into MAC.  Maybe more ICMP error management could be moved away
too.  There are a few other heavy IP features in DAD, ND and ICMP that
could be moved away down into MAC, because MAC can.

3. use of meta surfaces (aka Intelligent Reflecting Surfaces).  This is
a feature newly proposed in 6G that was never mentioned in earlier
generations, but it is a natural tool in the bag of the radio inclined
designer.  If range is not enough then put a reflecing surface there to
extend the range.  New in 6G is that these surfaces seem to be more
intelligent at PHY layer - it's not just a piece of concrete (like a
mirror) but some nano electronics are put on it to reflect in a more
intelligent way.

What does mean such a range extender to IP?  Will a link between UE and
base station have a 3 IP address structure (rathern than currently 2,
for ppp), where the intermediary IP address would be reserved to the
reflecting surface?  Would there be IP routing between UE, surface and
base station?

4. there is listed a need of awareness of neighbors in 6G links.  In
that need, it might become apparent that UEs dont talk always to the
base station but some times might talk to each other directly.  This is
a direction that was proposed since the 3G proposals, but never
materialized.  Even now there are such proposals in 5G but they might
not fly either (I think).

However, if this "neighbor awareness" feature for 6G does materialise,
then the immediate question for IP is how ND for 6G links will work?
(ND==Neighbor Discovery, a protocol in IPv6).  Will 6G access links
offer a form of multicast primitives in the MAC layer?

Since there will be more bandwidth available, maybe new MAC messages
will be added to help building the multicast state.  Once that is
realized, the 'all-nodes' kinds of multicast addresses needed for ND
will be available easily (as opposed to currently local filters to
implement such multicast addresses, no messaging).

Alex

---

From: Behcet Sarikaya <[email-masked]>
Date: Thu, 3 Dec 2020 10:22:21 -0600

Hi all,

Thanks Alex for your reply.
To all in the list: please get in the discussions, express your opinion,
don't be shy. We would like to have people in this list to actively
participate in the discussion.
If you don't like the direction proposed, e.g. in Alex mail, propose
whatever you like.
Maybe that way, someday we can get enough material to go for a BOF on 6G,
why not?

Dirk & Behcet

On Thu, Dec 3, 2020 at 5:33 AM Alexandre Petrescu <
[email-masked]> wrote:

> --
> 6gip mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/6gip
>