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<div class="div">
<h2>Interworking with other features</h2>

<p>The implementation of GPRS causes changes to the following existing
functions of the BSC:</p>


<ul>
<li><p>the PCU plug-in unit is introduced in Hardware Configuration
Management</p>
</li>
<li><p>GPRS-related radio network parameters are introduced in Radio
Network Configuration Management</p>
</li>
<li><p>co-operation between circuit switched traffic and GPRS traffic
is defined in Radio Channel Allocation</p>
</li>
<li><p>GPRS traffic is monitored by GPRS-specific measurements and counters</p>
</li>
<li><p>the serving PCU must be same for all the TRXs under one segment.</p>
</li>
</ul>


<p>The implementation is described in detail in <em>Radio network management
for GPRS in BSC</em>, <em>Gb interface configuration and state management</em>, <em>Radio
resource management</em>, and GPRS radio connection control. <em>GPRS
statistics in BSC</em> introduce the new GPRS measurements. </p>


<p>In the BSC the introduction of GPRS means dividing the radio resources
— circuit switched and GPRS traffic — into two territories. This has an effect
on the radio channel allocation features in which the BSC makes decisions
based on the load of traffic. For some features only the resources of the
circuit switched territory are included in the decisions. However, for most
features also the traffic channels in the GPRS territory need to be taken
into consideration when the BSC defines the traffic load, because radio time
slots (RTSL) in the GPRS territory may be allocated for circuit switched traffic
if necessary. Only if there are radio time slots that are permanently reserved
for GPRS use (dedicated GPRS resources), these cannot be used for circuit
switched calls and the BSC totally excludes these in its decisions on traffic
load.</p>


<a name="jan19515542339" shape="rect"></a>
<div class="topic">
<h3>Extended Cell Range</h3>

<p>Cell resources in the extended area of a cell are not used for GPRS.</p>


<a name="jan19515544140" shape="rect"></a>
<dl class="note-notification">
<dt class="note-caption">Note</dt>
<dd>Packet control channels cannot be used with Extended Cell Range. </dd>
</dl>
</div>


<a name="jan1951555041" shape="rect"></a>
<div class="topic">
<h3>Frequency Hopping</h3>

<p>In Baseband hopping radio time slot 0 belongs to a different hopping
group from other radio time slots of a TRX. This makes radio time slot 0 unusable
for multislot connections. If Baseband hopping is employed in a BTS, radio
time slot 0 of any TRX in the BTS will not be used for GPRS. </p>


<p>Both RF and Baseband hopping are supported in EGPRS.</p>
</div>


<a name="jan19515552542" shape="rect"></a>
<div class="topic">
<h3>Optimisation of the MS Power Level</h3>

<p>The BSC attempts to allocate the traffic channels within the circuit
switched territory according to the interference level recommendation the
BSC has calculated, in order to allow the performing of optimisation of the
MS power level. When the BSC has to allocate a traffic channel for a circuit
switched request in the GPRS territory, the interference level recommendation
is no longer the guiding factor. Now the first GPRS radio time slot beside
the territory border is taken regardless of its interference level being among
the recommended ones or not. Refer to <em>Radio resource management</em>
for more information on the division of territories. </p>
</div>


<a name="jan19515554843" shape="rect"></a>
<div class="topic">
<h3>Intelligent Underlay-Overlay</h3>

<p>Super-reuse frequencies are not supported for GPRS.</p>
</div>


<a name="jan19515555944" shape="rect"></a>
<div class="topic">
<h3>Dynamic Hot Spot</h3>

<p>For the Dynamic Hot Spot also the possible traffic on the GPRS channels
is meaningful. The radio time slots in GPRS traffic are regarded as busy channels
in the algorithms of the Dynamic Hot Spot during traffic channel allocation.
On the other hand, the BSC applies the Dynamic Hot Spot algorithm when it
allocates radio time slots for GPRS use in case the radio time slots are above
and beyond the operator-defined GPRS territory. When allocating the default
GPRS territory that the operator has defined with the parameter <span class="parameter-sem">default
GPRS capacity (CDEF)</span>, the BSC does not apply the Dynamic Hot Spot algorithm.</p>
</div>


<a name="jan19515565145" shape="rect"></a>
<div class="topic">
<h3>Dynamic SDCCH allocation </h3>

<p>The BSC selects a traffic channel time slot to be reconfigured as a
dynamic SDCCH time slot always within the circuit switched territory. </p>
</div>


<a name="jan19515571446" shape="rect"></a>
<div class="topic">
<h3>TRX prioritisation in TCH allocation</h3>

<p>The operator can set the BCCH TRX or the non-BCCH TRXs as preferred
for the GPRS territory with the parameter prefer BCCH frequency GPRS (BFG).
If no preference is indicated, then no prioritisation will be used between
different TRX types when forming the GPRS territory either. </p>
</div>


<a name="jan19515573347" shape="rect"></a>
<div class="topic">
<h3>Trunk reservation</h3>

<p>In trunk reservation the BSC defines the number of idle traffic channels.
The BSC adds together the number of idle traffic channels in the circuit switched
territory and the number of traffic channels in the radio time slots of the
GPRS territory, excluding the ones that are in the radio time slots that the
BSC has allocated permanently for GPRS.</p>
</div>


<a name="jan19515575048" shape="rect"></a>
<div class="topic">
<h3>TRX fault</h3>

<p>When a TRX carrying traffic channels becomes faulty, the radio time
slots on the TRX are blocked from use. The BSC releases the possible ongoing
calls and the call control resources. The BSC downgrades the traffic channels
belonging to the GPRS territory in the faulty TRX from GPRS use. To replace
the lost GPRS capacity the BSC determines the possibility of a GPRS territory
upgrade in another TRX. Refer to Radio resource management for more information
on GPRS territory upgrades and downgrades.</p>


<p>If the faulty TRX functionality is reconfigured to another TRX in the
cell, the GPRS-enabled TRX is also transferred to the new TRX.</p>


<p>If the faulty TRX is EDGE-capable, and GPRS in enabled in the TRX and
EGPRS is enabled in the BTS, the system tries to reconfigure its functionality
to another EDGE-capable TRX in the BTS.</p>
</div>


<a name="jan19515582049" shape="rect"></a>
<div class="topic">
<h3>Resource indication to MSC</h3>

<p>In general the BSC’s indication on the resources concerns traffic channels
of a BTS excluding those allocated permanently to GPRS (dedicated GPRS channels).
GPRS territory resources other than the dedicated ones are regarded as working
and idle resources.</p>
</div>


<a name="jan19515583350" shape="rect"></a>
<div class="topic">
<h3>Half Rate</h3>

<p>Permanent type half rate time slots are not used for GPRS traffic. Thus
it is recommended not to configure permanent half rate time slots in TRXs
that are planned to be capable of GPRS. </p>


<p>When the BSC can select the channel rate (full rate or half rate) to
be used for a circuit switched call based on the traffic load of the target
BTS, the load limits used in the procedure are calculated using the operator
defined BSC and BTS parameters <span class="parameter-sem">lower limit for HR TCH
resources (HRL), upper limit for HR TCH resources (HRU), lower limit for FR
TCH resources (FRL),</span> and <span class="parameter-sem">upper limit for FR TCH
resources (FRU)</span>. The BSC parameter <span class="parameter-sem">CS TCH allocation
calculation (CTC)</span> defines how the GPRS territory is seen when the load
limits are calculated. Depending on the value of <span class="parameter-sem">CTC</span>
either only CS territory or both CS and GPRS territories (excluding the dedicated
GPRS timeslots) are used to calculate the load limits. Additionally, with
the <span class="parameter-sem">CTC</span> parameter the user can define whether
the resources in GPRS territory are seen as idle resources or as occupied
resources. </p>
</div>


<a name="jan1951611451" shape="rect"></a>
<div class="topic">
<h3>High Speed Circuit Switched Data (HSCSD)</h3>

<p>If GPRS has been enabled in a BTS, the HSCSD-related load limits are
calculated based on the existing HSCSD parameters and the following rules: </p>


<ul>
<li><p>the number of working resources includes all the working TCH/F
resources of a BTS, excluding the ones that have been allocated permanently
to GPRS </p>
</li>
<li><p>the number of occupied TCH/F resources includes all the occupied
TCH/Fs of the circuit switched territory, as well as the default GPRS territory
TCH/Fs, excluding the GPRS radio time slots defined as dedicated </p>
</li>
<li><p>HSCSD parameter <span class="parameter-sem">HSCSD cell load upper limit
(HCU)</span> is replaced with the radio network GPRS parameter <span class="parameter-sem">free
TSL for CS downgrade (CSD)</span> if the latter is more restricting; thus the
one is used that limits HSCSD traffic earlier.</p>
</li>
</ul>


<p>The parameter <span class="parameter-sem">free TSL for CS downgrade (CSD)</span>
defines a margin of radio time slots that the BSC tries to preserve idle for
circuit switched traffic by downgrading the GPRS territory when necessary.</p>


<p>If HSCSD multislot allocation is denied based on the appropriate parameters,
the BSC rejects the transparent HSCSD requests and serves the non-transparent
HSCSD requests with one time slot. </p>


<p>If the time slot share in HSCSD allocation is not restricted, the transparent
requests are served preferably in the circuit switched territory, and only
if necessary in the GPRS territory. If a transparent HSCSD call ends up in
the GPRS territory, the BSC does not try to move it elsewhere with an intra
cell handover. Instead it tries to replace the lost GPRS capacity by extending
the GPRS territory on the circuit switched side of the territory border. </p>


<p>When the transparent HSCSD call inside the GPRS territory is later released,
the BSC returns the released radio time slots back to GPRS use to keep the
GPRS territory continuous and undivided. Refer to <em>Radio resource management</em>
for more information on how the resources form the territories. </p>


<p>The non-transparent HSCSD requests are always served in the circuit
switched territory as long as there is at least one TCH/F available. A normal
HSCSD upgrade procedure is applied later to fulfill the need of the non-transparent
request, if the call starts with less channels than needed and allowed. In
order for the non-transparent call to get the needed number of time slots,
the BSC starts an intra cell handover for suitable single slot calls beside
the non-transparent HSCSD call. At the start of the handover, the BSC checks
that a single slot call can be moved to another radio time slot and that HSCSD
upgrade is generally allowed.</p>


<p>A non-transparent HSCSD call enters the GPRS territory only in case
of congestion of the circuit switched territory. If multislot allocation was
originally defined as allowed, it will be applied also within the GPRS territory
to serve the non-transparent request. If the BTS load later decreases, so
that an GPRS territory upgrade becomes enabled, the non-transparent HSCSD
call is handed over to another location in the BTS so that the GPRS territory
can be extended. </p>


<p>When deciding whether to downgrade an HSCSD call or the GPRS territory
the BSC checks first if the margin of idle resources defined by the parameter <span class="parameter-sem">free TSL for CS downgrade (CSD)</span> exists. If a sufficient
margin exists, the BSC acts as without GPRS; that is, using the state information
that the HSCSD parameters define for the BTS, the BSC performs an HSCSD downgrade
if necessary. If the number of idle resources is below the parameter <span class="parameter-sem">free TSL for CS downgrade (CSD)</span>, then the actions proceed
as follows: </p>


<ul>
<li><p>if there are GPRS radio time slots that are above and beyond
the operator defined default GPRS territory then these additional GPRS radio
time slots are the first target for the GPRS territory downgrade</p>
</li>
<li><p>if there are no additional GPRS radio time slots, the BSC examines
if there are more HSCSD traffic channels than the parameter <span class="parameter-sem">HSCSD
TCH capacity minimum (HTM)</span> requires and if so, executes an HSCSD downgrade </p>
</li>
<li><p>if the minimum HSCSD capacity is not in use, then an GPRS territory
downgrade is made to maintain the margin defined by the parameter <span class="parameter-sem">free
TSL for CS downgrade (CSD)</span>. </p>
</li>
</ul>


<p>As a TCH/F becomes free through a channel release, the BSC first examines
the need and possibility for an HSCSD upgrade. If the BSC starts no HSCSD
upgrade, it further checks the need and possibility for an GPRS upgrade. The
GPRS territory can be upgraded although the parameter <span class="parameter-sem">HSCSD
TCH capacity minimum (HTM)</span> is not in use and there are pending HSCSD
connections in the cell. The parameter <span class="parameter-sem">free TSL for
CS upgrade (CSU)</span> and the margin it defines is the limiting factor for
GPRS territory upgrade. </p>


<p>free TSL for CS upgrade (CSU) defines the number of radio time slots
that has to remain idle in the circuit switched territory after the planned
GPRS territory upgrade has been performed.</p>


<p>Refer to <em>Radio resource management</em> for more information
on GPRS territories, and HSCSD and 14.4 kbit/s Data Services in BSC for more
information on the HSCSD feature. </p>
</div>


<a name="jan19516131252" shape="rect"></a>
<div class="topic">
<h3>Radio Network Supervision </h3>

<p>Actions of the radio network supervision do not apply for time slots
that have been included in the GPRS territory. The only reasonable thing to
monitor is the uplink interference on time slots in GPRS use. </p>


<p>Radio Network Supervision does not apply to the packet control channel. </p>
</div>


<a name="jan19516134053" shape="rect"></a>
<div class="topic">
<h3>BTS testing</h3>

<p>BTS testing cannot be executed on the packet control channel. </p>
</div>


<a name="jan1951614054" shape="rect"></a>
<div class="topic">
<h3>Multi BCF Control, Common BCCH Control</h3>

<p>The Multi BCF feature introduces a new radio network object called the
Segment. Several BTS objects can belong to one Segment. Only one BTS object
of the Segment can have a BCCH. The Segment can have BTS objects, which differ
in:</p>


<ul>
<li><p>frequency band (GSM800, PGSM900, EGSM900, GSM1800, and GSM1900)</p>
</li>
<li><p>power levels (Talk-family and UltraSite base stations) </p>
</li>
<li><p>regular and super-reuse frequencies </p>
</li>
<li><p>normal and extended cell radius frequencies</p>
</li>
<li><p>EDGE capability.</p>
</li>
</ul>


<p>TRXs inside a BTS object must have common capabilities. An exception
to this is that EDGE-capable and non-EDGE-capable TRXs can be configured to
the same BTS object. In this case, GPRS must be disabled in the non-EDGE-capable
TRXs. GPRS territory can be defined to each BTS object separately. GPRS and
EGPRS territories cannot both be defined to a BTS object at the same time.
Super-reuse and extended cell radius frequencies are not supported in GPRS.</p>


<p>There is only one BCCH /CCCH and one or no PBCCH /PCCCH in one Segment. </p>


<a name="jan19516151756" shape="rect"></a>
<dl class="note-notification">
<dt class="note-caption">Note</dt>
<dd>You must define GPRS territory to the BCCH frequency band in a Common
BCCH cell in which more than one frequency band is in use. Otherwise the GPRS
feature will not work properly in the cell. The reason for this requirement
is that in cases when the MS RAC of the GPRS mobile is not known by the BSC,
the TBF must be allocated on the BCCH frequency band first. During the first
TBF allocation, the GPRS mobile indicates its frequency capability to the
BSC. After that other frequency bands of the cell can be used for the GPRS
mobile accordingly.</dd>
</dl>


<a name="jan19516153757" shape="rect"></a>
<dl class="note-notification">
<dt class="note-caption">Note</dt>
<dd><p>GPRS territory must be configured into the BCCH BTS of a segment with
two or more BTSs on the BCCH band if PBCCH is not used and BTS(s) containing
GPRS channels are hopping.</p>



<p>This is due to the fact that without PBCCH, hopping frequency parameters
are encoded to the Immediate Assignment on CCCH with indirect encoding. When
the allocated BTS is hopping, indirect encoding can only refer to the System
Information 13 message, which in the Nokia BSS contains GPRS Mobile Allocation
only for the BCCH BTS. </p>



<p>The limitation to use only indirect encoding with hopping frequency
parameters in Immediate Assignment comes from the fact that Immediate Assignment
message segmentation is not supported in the Nokia BSS. The other two possible
hopping frequency encodings, direct 1 and 2, might use a large number of octets
for the frequency hopping. Large sized frequency parameters cause control
message segmentation. Thus as Immediate Assignment segmentation is not supported,
direct 1 and 2 encoding cannot be used.</p>



<p>Therefore, in a segment where BCCH band GPRS channels are on hopping
BTS(s), the TBFs must initially be allocated to the BCCH BTS. Later, the TBFs
may be reallocated to other BTSs as well. </p>
</dd>
</dl>


<p>See <em>Common BCCH Control in BSC</em> and <em>Multi BCF Control
in BSC</em> for more information on Multi BCF and Common BCCH.</p>
</div>
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