2 LTE Cell Planning

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Confidential Information of Huawei. No Spreading Without Permission

LTE Cell Planning


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The general process includes information collection, pre-planning, detailed planning,

and cell planning. In the cell planning, main concerns are frequency planning, TA

planning, PCI planning, and PRACH planning.


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There are several new frequency band options for LTE, some of which are available now or

should be within the next few years. These include the 700MHz, AWS (Advanced Wireless

Services) and 2.6GHz bands, as well as the re-use of existing GSM 900MHz and 1800MHz

bands. In addition, due to poor harmonization, there are other spectrum bands available,

including: 850MHz, 1500MHz, 1700MHz and 1900MHz.


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Application scenario: Adapt to situations with integrated operator frequency resources

and consecutive frequency bands. If the frequency point bandwidth is wide (>=10MHz), it

can be used as the initial network construction mode of the urban or densely-populated

urban areas. Basically satisfy the phase one capacity requirements. Use relatively narrow

frequency point bandwidth (


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Application scenario:

Adapt to situations that the operator frequency resources are rich or frequencybands dispersed and bandwidth is narrow.

The system capacity is dependent on the bandwidth of single frequency point. If

the bandwidth of frequency point is wide (>=5MHz), it can be used on initial

network construction of dense or common urban. If the bandwidth of frequency

point is narrow (


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ICIC is a technology that mitigates inter-cell interference together with the scheduling and

power control technologies. ICIC is applied at the Medium Access Control (MAC) layer.

ICIC restricts highly interfering CEUs within the orthogonal bands at the edge of cells or

schedules the CEUs in neighboring cells at different points of time. In this way, ICIC

mitigates inter-cell interference, increases the CEU throughput, and improves the system

coverage. This document provides the details on ICIC.


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TA: Similar to the location area and routing area in 2G/3G networks, the tracking area

(TA) is used for paging. TA planning aims to reduce location update signaling caused

by location changes in the LTE system.

TA list : A list of TAIs that identify the tracking areas that the UE can enter without

performing a tracking area updating procedure. The TAIs in a TAI list assigned by an

MME to a UE pertain to the same MME area. In LTE system, if an UE changes the

TAs in the TAI list, TA update wont be triggered.


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In the Los Angles, there are several independent density area that connected by the main

road (like island) . The UE may go across the different area through this road.


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In this scenario, users are average distributed in each area


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A TA coverage should be proper setting according to the capability of EPC

When the suburban area and urban area are covered discontinuously, an independent TAis used for the suburban area.


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LTE can be operated on different frequency band, we can plan the TA based on both

frequency band or geographical area

A TA should be planned for a continuous geographical area to prevent segmental

networking of eNBs in each TA.

The mountain or river in the planned area can be used as the border of a TA to reduce the

overlapping depth of different cells in two TAs. In this way, fewer location updates are

performed on the edge of a TA.

The LAC planning in the existing 2G/3G networks can serve as a reference for

planning TAs.


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PCI: Physical Cell ID, is used to generate scrambling code to identify the different cell


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Differences between a scrambling code and a PCI: The scrambling code ranges from

0 to 511 whereas the PCI ranges from 0 to 503. In addition, the protocols do not have

specific requirements for scrambling code planning. Therefore, only the reuse

distance needs to be ensured in scrambling code planning. For PCI planning,

however, 3GPP protocols require that the value of PCI/3 should be 0, 1, or 2 in each

eNB.


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The random access procedure is used in various scenarios, including initial access,

handover, or re-establishment. Like other 3GPP systems the random access procedure

provides a method for contention and non-contention based access. The PRACH (Physical

Random Access Channel) includes RA (Random Access) preambles generated from ZC

(Zadoff-Chu) sequences.

There are five preamble formats defined which four of them are for FDD


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PRACH configuration is defined by the following parameters

Root sequence, setting in the eNodeB Ncs: Automatically setting based on the cell radius configuration

PRACh frequency offset: Scheduled by eNodeB

High speed flag: Indicate whether the cell is for high speed

All the parameters all carried by Sib2


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There are 64 available preamble sequences in each cell. The 64 preamble sequences

are first generated from a root Zadoff-Chu sequence using cyclic shift. If less than 64

preamble sequences are generated, the remaining are generated from the root

Zadoff-Chu sequence corresponding to the logical index.

The preamble sequences are generated from the root Zadoff-Chu sequence through the

cyclic shift.


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Here is an example for the root sequence planning, suppose the cell radius is 10km

The Ncs value is determined by the cell radius. If the cell radius is 10 km, theNcs value is 76

The value of 839/76 is rounded down to 11, that is, each index can generate

11 preamble sequences. In this case, six root sequence indexes are required

to generate 64 preamble sequences.

The number of available root sequence indexes is 139 (0, 6, 12828)

The available root sequence indexes are assigned to cells. The assignment

principles are similar to those for PCIs.


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LTE Cell Planning

Date post:	10-Feb-2018
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