PHS MoU Document
B-IF 2.03-01-TS
Title : Public Personal Handy-Phone System: Interface between
Public Cell Station and ISDN-based PHS Switching Center-Layer
2 Specification
Version : 01
Date: Dec. 17, 1996
PHS MoU Classifications : Unrestricted
List of contents:<Summary>
1. Relation with international standards
2. Differences from ITU-T Recommendation Q.921
3. References
4. Items for further study< Layer 2 Specification >Number of pages: 3

PHS MoU Group
c/o Association of Radio Industries and Businesses (ARIB)
14F, Nittochi Building, 4-1, Kasumigaseki 1-choume, Chiyoda-ku, Tokyo 100, Japan
TEL +81-3-5510-8599 FAX +81-3-3592-1103© PHS MoU Group 1996

PHS MoU Document
B-IF 2.03-01-TS
VersionHistory of Revised Versions
DateOutline

01

17 April 1996 Established01

17 Dec. 1996

xDocument No. is changed (FormerlyIF2.03)
xDocument title is changed. (Formerly
Personal Handy-Phone System Public Cell
Station – ISDN Interface –Layer 2Specification–)

B-IF2.03-01-TS
Public Personal Handy-Phone System :Interface between Public Cell Station and ISDN-based PHS
Switching Center-Layer 2 Specification<Summary>

1. Relation with international standards
This specification conforms to ITU-T Recommendation Q.921.
2. Differences from ITU-T Recommendation Q.921
The ITU-T Recommendation specifies options for each of the following items and this specification
recommends the specific options described below as a reference. It is a sub-set of ITU-T Q.921 andmay be used to realize the minimum PHS functions.
(1) Initialization of link parameters
The ITU-T Recommendation provides an option for (a) initialization to the default values or (b)initialization based on negotiations with the peer as the methods of link parameter initialization.
(Refer to the ITU-T Recommendation Q.921 sub-clause 5.4, Appendix IV.)
This Specification recommends (a) initialization to the default values as the standard method for thefollowing reasons. The above ITU-T Recommendations does not sufficiently specify detailed
procedures using the XID frames. For example, judgment of whether or not the parameter
negotiation is permitted, and negotiation failure procedures are not clearly defined.
Furthermore, the burden on the network because of the need to support parameter negotiations forindividual links has not yet been properly analyzed.
(2) LAPB operation on the D-channel
The ITU-T Recommendations specifies LAPB (Refer to ITU-T Recommendation X.25) operation onthe D-channel as an option for both the user and the network. (Refer to ITU-T Recommendation
Q.921 clause 2.3.)
This specification does not standardize LAPB operation on the D-channel, but LAPD operation onlyis specified for the following reason. This Layer 2 Specification, concerned with LAPD operation,
does not need to describe specifications for LAPB operation and moreover PHS MoU Group does notfind it necessary to implement LAPB on the D-channel.
(3) Access procedure
The access procedure of the point-to-point data link is recommended only in this specification.

B-IF2.03-01-TS(1)(4) System parameter
N202, T201, and T202 system parameters are deleted, because it does not need procedure of a TEI ID
request.
(5) TEI value for point-to point signaling connection
The ITU-T Recommendation acknowledges that in certain applications it may be advantageous tohave a single point-to-point signaling connection provided for layer 3, and specifies a network optionof using "0" as the TEI value in such applications. (Refer to ITU-T Recommendation Q.921, AnnexA.)This specification recommends the use of "0" as the TEI value in the above application of a single
point-to-point signaling connection. (Thus, any frame having a TEI value other than 0 will bediscarded in the above application.)
The reason for the above recommendation is as follows.
Only one TEI value should be defined for the user-network interface when the data link layer has onlya single point-to-point signaling connection.
PHS MoU Group deems that defining a single TEI value would avoid confusion in determining theTEI value in the above application and would be effective from the point of view of standardization.
3. Reference
ITU-T Recommendations: Q.921
4. Item for further study(1) The access procedure of the point-to-multipoint data link
The access procedure of the point-to-multipoint data link which is not specified in above minimum
set specification is an item of further study for the following reason. It is necessary to study thefeasibility of application to supplementary services etc. realized in the near future.

(2)

B-IF2.03-01-TS

B-IF2.03-01-TS
Public Personal Handy-Phone System :Interface between Public Cell Station and ISDN-based PHS
Switching Center-Layer 2 Specification

Same specification as is specified in ITU-T Recommendation Q.921 is applied.

B-IF2.03-01-TS(3)