Subject: [mobile-ip] comments on draft-kempf-cdma-appl-02.txt

From: "Kuntal Chowdhury" <[email-masked]>
Date: Tue, 2 Oct 2001 11:17:10 -0500

Hi,

We have some comments on the "draft-kempf-cdma-appl-02.txt". We agree with
the main objective of this draft. We are also in agreement with the summary
section i.e. "existing micromobility scheme in a CDMA network need not be
replaced with MIP and likes".

A few comments on the text:

1. The definition of soft handoff needs to be corrected. Soft handoff is
always happening in a CDMA network. Alternatively a mobile in a CDMA network
maintains a set of PNs called active set. The notion of soft handoff from
one BTS to another is not correct.
 
2. The definition of 'hard handoff' needs some correction also. Hard handoff
happens between two BSCs, even if the BSCs belong to the same RAN.
 
3. Section 3 Page 8.
 
"When the mobile terminal begins to move out of range of stations B1 and B2,
the RAN gateway adds and deletes base stations from the set currently
serving the mobile node"
 
Apart from the RAN Gateway, which is essentially a BSC, the mobile station
itself performs the add/delete operation on the active set that it
maintains.
 
4. RAN connectivity is vital for managing this micro mobility events like
soft handoff, however in a large network or across different operator's
networks RAN connectivity may not be feasible. The extremely tight real time
constraints on traffic in the RAN limits the applicability of this scheme to
a small geographic area. 
 
5. Section 4. Page 8.
 
"This precludes routing IP packets from the mobile directly over the RAN" ->
Why so? Traffic engineered IP networks in the backhaul can be used to
satisfy stringent requirements of a CDMA backhaul network
 
6. The basic argument that hard handoff only takes place in the core network
is questionable.

-Kuntal

--------------------------------

To      IETF-Announce:
From  [email-masked]
Date   Mon, 24 Sep 2001 10:59:53 -0400
CC     [email-masked]
   
A New Internet-Draft is available from the on-line Internet-Drafts 
directories.

        Title           : IP Mobility and the CDMA Radio Access Network: 
                          Applicability Statement for Soft Handoff
        Author(s)       : J. Kempf, P. McCann, P. Roberts
        Filename        : draft-kempf-cdma-appl-02.txt
        Pages           : 12
        Date            : 21-Sep-01
        
Recently, there have been a variety of proposals submitted to the
Mobile IP Working Group and to other IETF working groups for IP
mobility solutions that seek to enhance or replace mobile IP. These
proposals, often characterized as micromobility or fast handoff, are
addressed primarily at the perceived need of multimedia sessions such
as video or voice over IP for faster handoff between radio base
stations, and are primarily directed at real time multimedia traffic
in 3rd generation cellular access networks. In this paper, we discuss
the design of CDMA radio access networks (RANs) and the applicability
of IP mobility to soft handoff in a CDMA RAN. We attempt to show that
given current IP routing algorithms and the constraints on a CDMA
RAN, IP mobility solutions have little, if any, role to play in
handoff within the RAN. In contrast, an IP mobility solution is
likely to play a big role in fast handoff between RANs, also called
hard handoff. While future developments in IP networking may change
this situation, IP mobility in CDMA networks currently seems to apply
only when the mobile node roams between disconnected RANs rather than
between base stations within a RAN or between connected RANs.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-kempf-cdma-appl-02.txt

To remove yourself from the IETF Announcement list, send a message to 
ietf-announce-request with the word unsubscribe in the body of the message.

Internet-Drafts are also available by anonymous FTP. Login with the username
"anonymous" and a password of your e-mail address. After logging in,
type "cd internet-drafts" and then
        "get draft-kempf-cdma-appl-02.txt".

A list of Internet-Drafts directories can be found in
http://www.ietf.org/shadow.html 
or ftp://ftp.ietf.org/ietf/1shadow-sites.txt

Internet-Drafts can also be obtained by e-mail.

Send a message to:
        [email-masked].
In the body type:
        "FILE /internet-drafts/draft-kempf-cdma-appl-02.txt".
        
NOTE:   The mail server at ietf.org can return the document in
        MIME-encoded form by using the "mpack" utility.  To use this
        feature, insert the command "ENCODING mime" before the "FILE"
        command.  To decode the response(s), you will need "munpack" or
        a MIME-compliant mail reader.  Different MIME-compliant mail readers
        exhibit different behavior, especially when dealing with
        "multipart" MIME messages (i.e. documents which have been split
        up into multiple messages), so check your local documentation on
        how to manipulate these messages.

Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.

<ftp://ftp.ietf.org/internet-drafts/draft-kempf-cdma-appl-02.txt>
     Content-type: text/plain

---

From: "Robert J Marks" <[email-masked]>
Date: Tue, 2 Oct 2001 11:57:42 -0500

Kuntal,
 
The decision to add or drop pilots from the active set is made by the
BSC, using input from the MS.
 
Bob

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]] On Behalf Of Kuntal
Chowdhury
Sent: Tuesday, October 02, 2001 11:17 AM
To: [email-masked]
Cc: Jayshree Bharatia
Subject: [mobile-ip] comments on draft-kempf-cdma-appl-02.txt

Hi, 

We have some comments on the "draft-kempf-cdma-appl-02.txt". We agree
with the main objective of this draft. We are also in agreement with the
summary section i.e. "existing micromobility scheme in a CDMA network
need not be replaced with MIP and likes".

1. The definition of soft handoff needs to be corrected. Soft handoff is
always happening in a CDMA network. Alternatively a mobile in a CDMA
network maintains a set of PNs called active set. The notion of soft
handoff from one BTS to another is not correct.

2. The definition of 'hard handoff' needs some correction also. Hard
handoff happens between two BSCs, even if the BSCs belong to the same
RAN.

3. Section 3 Page 8. 
  
"When the mobile terminal begins to move out of range of stations B1 and
B2, the RAN gateway adds and deletes base stations from the set
currently serving the mobile node"

Apart from the RAN Gateway, which is essentially a BSC, the mobile
station itself performs the add/delete operation on the active set that
it maintains.

4. RAN connectivity is vital for managing this micro mobility events
like soft handoff, however in a large network or across different
operator's networks RAN connectivity may not be feasible. The extremely
tight real time constraints on traffic in the RAN limits the
applicability of this scheme to a small geographic area. 

5. Section 4. Page 8. 
  
"This precludes routing IP packets from the mobile directly over the
RAN" -> Why so? Traffic engineered IP networks in the backhaul can be
used to satisfy stringent requirements of a CDMA backhaul network

6. The basic argument that hard handoff only takes place in the core
network is questionable. 

-Kuntal 

To      IETF-Announce: 

        

To remove yourself from the IETF Announcement list, send a message to 
ietf-announce-request with the word unsubscribe in the body of the
message. 

Internet-Drafts are also available by anonymous FTP. Login with the
username 
"anonymous" and a password of your e-mail address. After logging in, 
type "cd internet-drafts" and then 
        "get draft-kempf-cdma-appl-02.txt". 

Send a message to: 
        [email-masked]. 
In the body type: 
        
        a MIME-compliant mail reader.  Different MIME-compliant mail
readers