Thanks Thanks:  0
Showing results 1 to 3 of 3

Thread: UMTS Radio Network Planning , Design and Optimization

  1. #1
    BannedUser Reputation: 24
    Join Date
    2008-09-24
    Location
    Orala
    Posts
    157


    Default UMTS Radio Network Planning , Design and Optimization

    UMTS radio network planning and optimization is altogether a vast
    and interesting field.
    It involves the simple work of deploying the Node-B's and RNC's but,
    hold on...!!
    Complex estimations of various radio network parameters, Dimensioning,
    Detailed Planning and Optimization of radio network, Network simulation
    softwares and Field measurements are involved in enforcing the
    simplicity mentioned earlier!! The goal is to get sufficient coverage
    and capacity by maintaining the lowest possible deployment costs.
    Dimensioning:
    In this phase the basic general properties of the "would-be"
    network is investigated.
    This initial phase of Network Planning includes calculating the
    approximate number of Node-B's required, deciding the antenna heights
    and the network configuration parameters keeping in mind the kind of
    mobile services the service provider advertised to offer their
    customers!
    Detailed Planning:
    Usually a site-survey is done at first to get to know about the
    geographical locations,
    traffic volume in different areas*****ology planning and configuration
    planning is
    done in this stage.Power budget calculation, also called as link budget
    is done by taking all the available radio parameters that include
    information of different gains and losses in the communication path of
    the radio link.
    Cell breathing should be taken into account while calculating
    cell range in UMTS network.When the traffic in the cell increases, the
    sensitivity of the Node-B decreases
    because of the increased interference and so the UE will require more
    power to
    remain connected to the cell.And when there is not much load in the
    cell, the interference would be low and the UE can use the same power
    to connect to that particular cell even from a longer distance.This
    variation in cell ranges is called as cell breathing.
    Simply put, cell capacity influences cell coverage area.So one of the
    parameter in link budget is Interference margin.
    <i>MInterference, dB = 1...3 dB (20...50% Load).</i>

    Usually in RF Network planning, they start with uplink because
    the downlink is normally adjusted to balance the uplink by selecting
    the appropriate power amplifier at the base station. Near cell edges,
    the users transmit with full power to reach the Node-B and the inner
    loop power control mechanism in uplink causes a problem, because the UE
    cannot respond to power control commands due to limitations in
    transmission power capacity. This should be taken into account while
    calculating link budget, and it is done by introducing a Power control
    headroom margin also called as Fast fading margin, which guarantees
    continuous service for users in cell edges.
    The Fast fading margin or Power control headroom is given by

    <i>MFastFade, dB = 2...5 dB.</i>

    In UMTS, coverage and capacity planning are interrelated and
    cannot be done separately
    because of cell breathing phenomenon and they are done in planning
    phase called topology planning. In coverage planning accurate cell
    ranges are calculated from power budget calculations provided in
    configuration planning phase. Normally, cell coverage's are made to
    overlap excessively to give high service probability to users in cell
    edges, thus providing soft handover resulting in macro-diversity
    gains.But more number of soft handovers implies significant cost in the
    capacity. After measuring the pilot strength in the area, the size of
    handover zones within the cell footprint should be decreased. Handover
    zones should be shifted from high-traffic areas to low-traffic areas
    but at the same time should be strategically placed to get the
    advantage of macro-diversity gains
    for UEs in cell edges.
    The detailed planning phase includes usage of Network
    simulation soft wares for coverage and capacity estimations. The inputs
    include user traffic distributions and other network specific
    parameters. Simulations are mainly done to know the optimal number of
    Node-B's required,UE transmit powers etc.Simulation results are used
    for optimizing the network. However simulations are also done in
    parallel to actual planning before the network is actually launched.
    Base station locations should be selected so that they are always
    placed on the traffic hot spots, since this offers the best link budget
    for the mobile users served by those base stations.
    Field measurements are performed to study soft handover areas, network interference,
    and call drops that happen in the real network.Field measurements are mostly performed
    when planned coverage and propagatiion channel characteristics are examined in an already operational network.

    Before the network is launched code and parameter planning are
    needed. Certain amount of Channelisation codes(OVSF codes or walsh
    codes) are allocated for each cell to separate users in downlink
    direction. Optimization:

    The actual parameters being used in the real network are fine
    tuned for better performance. The power control parameters, number of
    channelisation codes being used in a particular cell and other critical
    parameters that have a great impact on the performance are optimized
    from the network simulation software and field measurements.Use of
    WCDMA repeaters is one way to increase coverage and capacity in an easy
    and affordable way.The article discussed only about Interference
    margin, Power control headroom margin and soft handover macro diversity
    gains.

  2. # ADS
    Circuit advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many
     

  3. #2
    Senior Member Reputation: 502
    Join Date
    2008-11-05
    Posts
    1,025


    Default

    Dear mansoor i would like to ask you do you have a document contain that you mentioned .thanks in advance

  4. #3
    Member Reputation: 323
    Join Date
    2009-04-05
    Posts
    270


    Default

    Did you forget to attach the document ??

Bookmarks

Bookmarks

Posting Rules

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •