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<div class="div">
<h1>Intelligent Coverage Enhancement</h1>

<p>Intelligent Coverage Enhancement (ICE) is a solution where</p>


<ol class="type-odd">
<li type="1"><p>The same area or sector is covered
by two cells with different output power and</p>
</li>
<li type="1"><p>These two cells share common antennas.</p>
</li>
</ol>


<p>Naturally, the coverage areas are not exactly the same
because of the difference in power, but it is characteristic for this arrangement
that the coverage area of the cell having smaller output power is totally
within the coverage area of a high power cell. Because of this, it is possible
to use common antennas for the two cells thus reducing the number of antennas
required.</p>


<p>In locations where it is necessary to cover as large an
area as possible with one cell a special configuration can be used. This feature
makes it possible to have 3dB more transmit power into the antenna connector.
The ‘normal’ way to configure the BTS is as follows:</p>


<a name="apr164910316" shape="rect"></a>
<div>
<img alt="urn:mars:dn0469768:1:en:global:tiff:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn0469768&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: 'Normal' way to configure the BTS</p>
</div>


<p>The ICE solution is configured by using 3 TRXs. The first
TRX is configured by bypassing the hybrid combiner, which increases the output
power by 3 dB, compared to the two other TRXs that are combined together into
another antenna. The following picture illustrates the ICE configuration.</p>


<a name="apr164983815" shape="rect"></a>
<div>
<img alt="urn:mars:dn0469826:1:en:global:tiff:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn0469826&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: The ICE configuration</p>
</div>


<p>The TRX1 is configured as its own cell with a larger service
area, and the TRX2 and 3 are configured then as another cell with a totally
overlapping service area. The TRX1 has a higher output power since the hybrid
is bypassed thus mobiles are likely to camp under it. Because of this, the
SDCCH capacity must be allocated for the TRX1 according to the needs of both
cells. It is necessary to hand all possible calls to the lower power cell
to save capacity for mobiles on the extended area. Umbrella handover can be
parameterised to take care of this. When moving away from the cell, handover
to a higher power cell takes place because of signal level and quality. A
directed retry can also be used to share traffic between the two cells.</p>


<p>It is also possible to use two high power TRXs by having
the hybrid bypassed in both AFEs. Then the capacity is limited to two TRXs/cell.
In this case, there is no need to divide TRXs into separate overlapping cells
as both TRXs have the same coverage.</p>


<p>In a new enhancement 'Handover support for coverage enhancement',
the call is always initiated in the coverage layer, but if the signal level
exceeds a predetermined threshold, the call can be handed over capacity layer.
On the other hand, if the signal level falls below the threshold or the call
suffers bad quality, the call is handed over the coverage layer. To have this
enhancement, only one BCCH per sector should be configured.</p>


<p>An enhancement 'Intelligent coverage enhancement with AFE&amp;RTC'
allows building AFE&amp;RTC ICE configuration that uses two antennas. With
two antennas, the maximum configuration becomes 6 TRX (= 1 coverage + 5 capacity
TRXs).</p>


<p>In an enhancement 'ICE support for booster', the transmit
booster can be used together with non-boosted TRX with the help of the ICE
concept. From the hardware configuration point of view, this is equal to a
dual duplex configuration where the other AFE is replaced with booster specific
filter unit, AFH. </p>


<p>For the 'ICE support for Booster' the boosted and non-boosted
TRXs have to be configured as separate cells each with their own BCCH. For
this reason, 'Handover support for coverage enhancement' is not supported
with 'ICE support for Booster'.</p>


<a name="mar94162171" shape="rect"></a>
<div class="topic">
<h2>ICE+
Configuration</h2>

<p>There is a new concept called ICE+. It is a single cell
with the BCCH only and defined in both the BTS and BSC as a single cell. Thus
no separate BCCH is needed for the low-power TRXs. This makes frequency planning
much easier and provides an extra traffic channel for the low-power TRXs.</p>


<p>These configurations extend the capacity of ICE-configured
sectors to two TRXs with combiner bypassed (high-power TRXs) and two or four
TRXs (low-power TRXs), which are combined in pairs by wideband combiner(s).
The high-power TRXs use an AFT filter unit, which has no combiner. Because
of this, there is 3 dB higher transmitting power than in the low-power TRXs,
which use one (for two TRXs) or two (for four TRXs) AFE filter units. This
results in a combination of good coverage from the high-power TRXs and high
traffic handling capacity because of the total of up to four or six TRXs in
one cell.</p>


<p>There are three basic variants of the configurations: </p>


<ul>
<li><p>2 TRXs/AFT + 2 TRXs/AFE, 3 Antennas </p>


<p>are used where a minimum number of antennas are needed.
Two antennas are used duplexed for both Tx and Rx, one antenna is used for
Tx only. MastHead Amplifiers (MHAs)are needed for link balance.</p>
</li>
<li><p>2 TRXs/AFT+2/4/6/8 TRXs/1-4 AFEs, 4/5/6
Antennas or 2/3 Cross-Polar Antennas</p>


<p>are used where easy expansion to 2 + 4 TRXs is to be allowed
for, or where four antennas are to be used, for instance, where cross-polar
antennas are used. All antennas are used duplexed for both Tx and Rx. MastHead
Amplifiers (MHAs) are needed for link balance on the AFT and may be used with
the AFE.</p>
</li>
<li><p>4 TRXs/2AFTs + 2/ TRXs, 6 Antennas
or 3 Cross-Polar Antennas</p>


<p>are used for the maximum capacity. </p>
</li>
</ul>


<p>In addition, AFE +AFE with a hybrid pass can be one configuration
for ICE+ as well.</p>


<p>Two example configurations are presented in the following
pictures:</p>
</div>


<a name="apr16410285719" shape="rect"></a>
<div class="topic">
<h2>2
+ 4 TRXs, 4 antennas</h2>

<a name="apr16410303721" shape="rect"></a>
<div>
<img alt="urn:mars:dn0469717:1:en:global:tiff:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn0469717&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: 2 + 4 TRXs, 4 antennas</p>
</div>


<p>One sector with 2 + 4 TRXs will fit within a single Nokia
Intratalk or Citytalk cabinet.</p>
</div>


<a name="apr16410291620" shape="rect"></a>
<div class="topic">
<h2>4
+ 4 TRXs, 6 antennas</h2>

<a name="apr16410311422" shape="rect"></a>
<div>
<img alt="urn:mars:dn0469771:1:en:global:tiff:data:data" border="0" src="NED?action=retrieve&amp;identifier=dn0469771&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /><p class="figure-caption">Figure: 4 + 4 TRXs, 6 antennas</p>
</div>


<p>Cross-polar antennas may be used for a reduced visual impact
as they require only two antenna assemblies at the masthead. Note that two
of the AFT antennas are used for Tx only. MastHead Amplifiers (MHAs) are needed
for link balance on the AFT and may be used with the AFE. </p>
</div>


<a name="apr1641416501" shape="rect"></a>
<div class="topic">
<h2>Multi-sector
use</h2>

<p>With extension cabinets, CityTalk and IntraTalk BTSs will
support up to three sectors with two high-power and two low-power TRXs each,
producing a total of 12 TRXs.</p>


<p>Similarly, CityTalk and IntraTalk BTSs with extension cabinets
will support two sectors with two high-power and four low-power TRXs each,
producing a total of 12 TRXs.</p>


<p>This ICE configuration is a sector solution; all other
sectors can have whatever configuration is necessary.</p>
</div>


<a name="apr164141722" shape="rect"></a>
<div class="topic">
<h2>Network
aspects</h2>

<p>The BCCH carrier must be in one of the two high-power TRXs.
The feature ‘BSS feature ‘Preferred BCCH TRX’ must be used to ensure this.
The SDCCH channel must also be in one of the two high-power TRXs and have
sufficient capacity to cover all the TRXs in the cell.</p>


<p>Also, with the single BCCH, all the low-power TRX frequencies
can be allocated with a high (non-BCCH) frequency reuse factor, and the IUO
(super-reuse) feature can also be used.</p>


<p>The normal BSC handover features will control the handovers
within the cell (between high-power and low-power TRXs) and between the ICE
cell and neighbouring cells. "Handover support for coverage enhancement" can
be applied to the ICE+.</p>
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