GPRS for Mobile Internet
This book helps you understand how the GPRS system is used as a major technology building block for the emerging mobile Internet; the book
also provides you with detailed coverage of a wide range of important topics.
TABLE OF CONTENTS GPRS for Mobile Internet
5.5: Radio Resource Allocation
5.5 Radio Resource Allocation
This section describes the procedures enabling the assignment of radio resource to the mobile and in consequence the establishment of a TBF. These procedures correspond to the transition from packet idle mode to packet transfer mode. The procedures used for the report of measurements are also detailed.
As described in Chapter 3, two kinds of TBF can be established:
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Uplink TBF assigning uplink radio resource to the mobile with a downlink signaling channel;
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Downlink TBF assigning downlink resources on shared PDCHs with an uplink signaling channel.
Two simultaneous TBFs assigned to the same MS in opposite direction (uplink and downlink) are said to be concurrent.
5.5.1 Uplink TBF Establishment
The mobile triggers the establishment of an uplink TBF for three major reasons:
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To perform an uplink data transfer;
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To answer a paging;
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To perform a GMM procedure (e.g., RA update procedure and GPRS attach procedure).
5.5.1.1 RACH/PRACH Phase
Access Request
The mobile triggers the establishment of an uplink TBF:
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By sending a CHANNEL REQUEST message on the RACH when there is no PBCCH in the cell;
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By sending a PACKET CHANNEL REQUEST message on the PRACH if PBCCH is present in the cell.
The mobile may also request the establishment of an uplink TBF during a downlink TBF on PACCH.
There are two codings for the PACKET CHANNEL REQUEST message. One format allows the transport of 8 bits information and the other one 11 bits information. The CHANNEL REQUEST message carries 8 bits of information.
The...
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