Subject: [manet] Document Action: 'The Dynamic Source Routing Protocol for Mobile Ad Hoc Networks (DSR)' to Experimental RFC

From: The IESG <[email-masked]>
Date: Tue, 30 May 2006 14:28:54 -0400

The IESG has approved the following document:

- 'The Dynamic Source Routing Protocol for Mobile Ad Hoc Networks (DSR) '
   <draft-ietf-manet-dsr-10.txt> as an Experimental RFC

This document is the product of the Mobile Ad-hoc Networks Working Group. 

The IESG contact persons are Bill Fenner and Ross Callon.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-manet-dsr-10.txt

Technical Summary
 
   The Dynamic Source Routing protocol (DSR) is a routing protocol
    designed specifically for use in multi-hop wireless ad hoc
   networks of mobile nodes.  DSR allows the network to be completely
   self-organizing and self-configuring, without the need for any
   existing network infrastructure or administration.
 
Working Group Summary
 
   The Working Group had consensus to publish the four existing protocols
   as Experimental, as the first step down the path towards DYMO.
 
Protocol Quality
 
   Bill Fenner reviewed the specification for the IESG.

Note to RFC Editor

Please make the following two changes:

OLD (title):

                  The Dynamic Source Routing Protocol
                    for Mobile Ad Hoc Networks (DSR)

NEW:

                  The Dynamic Source Routing Protocol
               for Mobile Ad Hoc Networks (DSR) for IPv4

OLD (near the end of section 1, change "are" to "will be"):

   This document specifies the operation of the DSR protocol for
   routing unicast IPv4 packets in multi-hop wireless ad hoc networks.
   Advanced, optional features, such as Quality of Service (QoS) support
   and efficient multicast routing, and operation of DSR with IPv6 [7],
   are covered in other documents.

NEW:

   This document specifies the operation of the DSR protocol for
   routing unicast IPv4 packets in multi-hop wireless ad hoc networks.
   Advanced, optional features, such as Quality of Service (QoS) support
   and efficient multicast routing, and operation of DSR with IPv6 [7],
   will be covered in other documents.

IANA Note

   Please reassign IP Protocol 48 to DSR.  David Johnson (the main
   author of DSR) was able to confirm that this protocol number was
   originally assigned for a proposal for Mobile IP (Mobile Host
   Routing Protocol) that was never deployed.  Under RFC 2780
   section 4.3, this is the IESG Approval of this assignment.

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---

From: "Yihu Li" <[email-masked]>
Date: Wed, 31 May 2006 12:15:52 -0400

Hi all,

I have a question about the synchronization problem in a SIMO system.

    S1(one antenna)-------->R (two antennas)<----------S2(one antenna)

In the scenario above, two transmitters S1 and S2 each have one antenna, and 
the receiver R has two antennas. Assuming spatial multiplexing mode is used, 
S1 first sends a packet to R, and then S2 also starts to send another packet 
to R while the transmission between S1 to R is still ongoing. Could R 
receive the two packets successfully or the two packets will be collided? If 
R can receive both, it has to first sychronize to S1 for reception, how can 
it sychronize to S2 thereafter? Is it possible?

Thanks.

Yihu

---

From: Joe Carey <[email-masked]>
Date: Wed, 31 May 2006 11:40:11 -0600

Yihu,

Yes, it is possible.  In fact, CDMA cell phones work this way (except R 
usually has only one antenna).  Typically we describe the problem with 
S1 and S2 being the same station, but it could be made to work with them 
being different stations.

It requires some fancy waveform coding.  You are correct, 
synchronization is one of the big issues.  Determining the propagation 
channel characteristics so you can sort it out on the far end is another 
big issue.

Here is a link to the Enhanced Wireless Consortium.  Download the 
802.11n draft spec, which gives some detail on a particular MIMO 
implementation:
http://www.enhancedwirelessconsortium.org/home
It'll cure any insomnia you might have.

You can also google or do a literature search on "space time coding."

joe

Yihu Li wrote:
> In the scenario above, two transmitters S1 and S2 each have one 
> antenna, and the receiver R has two antennas. Assuming spatial 
> multiplexing mode is used, S1 first sends a packet to R, and then S2 
> also starts to send another packet to R while the transmission between 
> S1 to R is still ongoing. Could R receive the two packets successfully 
> or the two packets will be collided? If R can receive both, it has to 
> first sychronize to S1 for reception, how can it sychronize to S2 
> thereafter? Is it possible?
>
> Thanks.
>
> Yihu
>

---

From: "Yihu Li" <[email-masked]>
Date: Wed, 31 May 2006 14:35:17 -0400

Hi Joe,

Thanks a lot.

I just want to double confirm the problem: nodes S1 and S2 are not 
synchronized in transmission (not as the conventional single-user MIMO in 
which multiple antennas in a transmitter transmit at the same time slot or 
MIMO coorperative communication in which the nodes with single antennas are 
coordinated to transmit at the same time slot). Instead, S1 and S2 start 
their transmissions in different time slots. So, you think node R can still 
receive the packets from both stations correctly in this case, right? If so, 
what is the differences/comlexities of this case to the one where 
transmissions through different antennas are synchronized?

Thanks again.

Yihu
----- Original Message ----- 
From: "Joe Carey" <[email-masked]>
To: "Yihu Li" <[email-masked]>
Cc: "manet mailing list" <[email-masked]>
Sent: Wednesday, May 31, 2006 1:40 PM
Subject: Re: [manet] A question in multiuser MIMO/SIMO

> usually has only one antenna).  Typically we describe the problem with S1 
> and S2 being the same station, but it could be made to work with them 
> It requires some fancy waveform coding.  You are correct, synchronization 
> is one of the big issues.  Determining the propagation channel 
> characteristics so you can sort it out on the far end is another big 
> issue.
>
> Here is a link to the Enhanced Wireless Consortium.  Download the 802.11n 
> draft spec, which gives some detail on a particular MIMO implementation:
>> In the scenario above, two transmitters S1 and S2 each have one antenna, 
>> and the receiver R has two antennas. Assuming spatial multiplexing mode 
>> is used, S1 first sends a packet to R, and then S2 also starts to send 
>> another packet to R while the transmission between S1 to R is still 
>> ongoing. Could R receive the two packets successfully or the two packets 
>> will be collided? If R can receive both, it has to first sychronize to S1 
>> for reception, how can it sychronize to S2 thereafter? Is it possible?
>>
>> Thanks.
>>
>> Yihu
>>

---

From: Joe Carey <[email-masked]>
Date: Wed, 31 May 2006 14:13:12 -0600

Hi Yihu,

Yes, its still possible when the systems are unsynchronized, but timing 
recovery is more complicated.  This is the CDMA reverse link problem, 
from the handset to the base station.  You might be tempted to argue 
that the handsets synchronize off the same forward link, but I would 
make the counterpoint that in a CDMA system the two handsets could be 
traveling and therefore have different doppler shifts and so are 
effectively unsynchronized.

The key to making this work is the coding.  Pick the right spreading / 
timing / synchronization / channel sounding codes and it can be made to 
work.

Another significant problem in the situation you describe is the 
difference in amplitude between signals received from S1 and S2.  If one 
station is closer than the other, coding gain alone will not be 
sufficient.  In that case you need to implement power control in place 
to keep the two signals received at R at approximately the same level, 
so that coding gain can effectively separate the two signals.

Ramanathan at BBN wrote an interesting paper recently on future network 
topologies that explored variations on this idea for ad-hoc networks.

joe

Yihu Li wrote:
> synchronized in transmission (not as the conventional single-user MIMO 
> in which multiple antennas in a transmitter transmit at the same time 
> slot or MIMO coorperative communication in which the nodes with single 
> antennas are coordinated to transmit at the same time slot). Instead, 
> S1 and S2 start their transmissions in different time slots. So, you 
> think node R can still receive the packets from both stations 
> correctly in this case, right? If so, what is the 
> differences/comlexities of this case to the one where transmissions 
> through different antennas are synchronized?
>
> Thanks again.
>
> Yihu
> ----- Original Message ----- From: "Joe Carey" 
> <[email-masked]>
>> Yes, it is possible.  In fact, CDMA cell phones work this way (except 
>> R usually has only one antenna).  Typically we describe the problem 
>> with S1 and S2 being the same station, but it could be made to work 
>> with them being different stations.
>>
>> synchronization is one of the big issues.  Determining the 
>> propagation channel characteristics so you can sort it out on the far 
>> end is another big issue.
>>
>>> also starts to send another packet to R while the transmission 
>>> between S1 to R is still ongoing. Could R receive the two packets 
>>> successfully or the two packets will be collided? If R can receive 
>>> both, it has to first sychronize to S1 for reception, how can it 
>>> sychronize to S2 thereafter? Is it possible?
>>>
>>> Thanks.
>>>
>>> Yihu
>>>

---

From: "Yihu Li" <[email-masked]>
Date: Wed, 31 May 2006 21:20:07 -0400

Hi Joe,

Thank you for your explaination. It helps a lot.

As you pointed out, "The key to making this work is the coding.  Pick the 
right spreading /  timing / synchronization / channel sounding codes" and 
"timing recovery is more comlicated". So, do you know any work on this, that 
is, coding and timing recovery to make this work or discuss this? Any 
reference will be great helpful.

Regards,

Yihu
----- Original Message ----- 
From: "Joe Carey" <[email-masked]>
To: "Yihu Li" <[email-masked]>
Cc: "manet mailing list" <[email-masked]>
Sent: Wednesday, May 31, 2006 4:13 PM
Subject: Re: [manet] A question in multiuser MIMO/SIMO

> recovery is more complicated.  This is the CDMA reverse link problem, from 
> the handset to the base station.  You might be tempted to argue that the 
> handsets synchronize off the same forward link, but I would make the 
> counterpoint that in a CDMA system the two handsets could be traveling and 
> therefore have different doppler shifts and so are effectively 
> unsynchronized.
>
> sufficient.  In that case you need to implement power control in place to 
> keep the two signals received at R at approximately the same level, so 
> that coding gain can effectively separate the two signals.
>
>> which multiple antennas in a transmitter transmit at the same time slot 
>> or MIMO coorperative communication in which the nodes with single 
>> antennas are coordinated to transmit at the same time slot). Instead, S1 
>> and S2 start their transmissions in different time slots. So, you think 
>> node R can still receive the packets from both stations correctly in this 
>> case, right? If so, what is the differences/comlexities of this case to 
>> the one where transmissions through different antennas are synchronized?
>>
>> Thanks again.
>>
>> Yihu