Soft Frequency Reuse in LTE

Frequency Reuse is a well known concept that has been applied to wireless systems over the past two decades e.g. in GSM systems. As the name suggests Frequency Reuse implies using the same frequencies over different geographical areas. If we have a 25MHz band then we can have 125 GSM channels and 125*8=1000 time multiplexed users in a given geographical area. Now if we want to increase the number of users we would have to reuse the same frequency band in a geographically separated area. The technique usually adopted is to use a fraction of the total frequency band in each cell such that no two neighbor cells use the same frequency. Typically the frequency band is divided into 3 or 7 cells.

7-Cell Frequency Reuse in GSM
7-Cell Frequency Reuse in GSM

The division of the frequency band in to smaller chunks reduces the system capacity e.g. one cell with 25 MHz bandwidth would have much higher capacity then 7 cells having 3.5 MHz each. To overcome this problem a frequency reuse of 1 has been proposed i.e. each cell has the full system bandwidth (nearly). The problem of co-channel interference at the cell boundaries is resolved by dedicating a small chunk of the available spectrum for the cell edges.

Frequency Planning and Power Allocation for SFR Scheme
Frequency Planning and Power Allocation for SFR Scheme

In Soft Frequency Reuse (SFR) the cell area is divided into two regions; a central region where all of the frequency band is available and a cell edge area where only a small fraction of the spectrum is available. The spectrum dedicated for the cell edge may also be used in the central region if it is not being used at the cell edge. The lack of spectrum at the cell edge may result in much reduced Shannon Capacity for that region. This is overcome by allocating high power carriers to the users in this region thus improving the SINR and the Shannon Capacity.

Note:
1. The Signal to Interference and Noise Ratio is given as:
SINR=Signal Power/(Intercell Interference+Intracell Interference+AWGN Noise)
2. Typically the term capacity was used to describe the number of voice channels (or users) that a system can support. But with modern digital communication systems it usually refers to the Shannon Capacity that can be achieved (in bits/sec/Hz).

[1] Yiwei Yu, Eryk Dutkiewicz, Xiaojing Huang, Markus Mueck and Gengfa Fang, “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks”, ISCIT 2010.

0.00 avg. rating (0% score) - 0 votes

37 thoughts on “Soft Frequency Reuse in LTE

    1. I do not think I fully understand what you are asking but let me try to answer…frequency allocation is something which changes with region because the regulators look at the requirements of their own region…like FCC does the regulation in the USA…phones have the capability to work around the world so they support most of the frequencies that are allocated…please have a look at the following post

      http://www.raymaps.com/index.php/lte-spectrum-allocation/

  1. Hello sir,i m not able to get full paper,only abstract part is getting displayed.can u guide me sir ,i need different frequency reuse schemes nd thier application.
    thank you sir

  2. hello sir can u explain me the differences between partial frequency reuse,soft frequency reuse and fractional frequency reuse schmes,with thier basic function

    1. Have you looked at the following reference:
      Yiwei Yu, Eryk Dutkiewicz, Xiaojing Huang, Markus Mueck and Gengfa Fang, “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks”, ISCIT 2010.

  3. I m doing ME project,“Performance analysis of soft frequency reuse for LTE Advance system with carrier aggregation.can u help me with the codes for SFR and thesis report.

    1. Thesis report and code must be your original work. You will not learn much by copy pasting. But if you have some specific questions maybe I can help.

  4. I am doing M.Tech project on soft frequency reuse in lte to increase performance of QoS parameters. So I am in need of sample codes on soft frequency reuse to simulate in matlab.Please kindly help.

  5. DEAR ALL..

    I’m a student doing thesis in the area of Soft Frequency Reuse. How can I obtain the simulator codes of the paper “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks” it is very important to me please if any one can help me with this.

    Thanks in advance

  6. Dear ALL,

    I am currently doing my final year project on Dense Small cell networks at Makerere University with concentration on pico cells. However during my final year project proposal presentation, the following concerns were raised by the panel.

    1) What are the key challenges being brought by small cells deployment in-terms of its high level of frequency reuse and it’s Spectral concerns.

    2)How can its frequent hand over problems be mitigated.

    3)What are the most likely challenges to arise in moving towards dense small network and how can it be mitigated.

    please help me with some documents that will help me to solve those issues.
    You can also send for me some of the sources where i can find it.

    Thanks in advance

    1. 1. One problem that I foresee is that of co-channel interference but this can be mitigated by using directional antennas.

      2. Frequent handovers can be avoided by having a super-cell for fast moving users and smaller cells (within super-cell) for stationary or slow moving users.

      John

  7. Hello, I’m doing B.Tech final year project on SFR in LTE ..
    So I need MatLab codes..
    I hope I will get.
    Thanks in advance

  8. hello John
    I’m a student doing thesis in the area of Soft Frequency Reuse.
    I really need to simlulate on matlab but I need the codes for SFR.
    Thanks in advance

  9. Hello,
    I´m a student of Mexico and now, I’m doing my thesis about throughput for arrival rate, I am stuck in Simulation .
    I need your help .Thanks

  10. I am conducting my Final year B.Sc Thesis on Performance analysis of Softer Frequency Reuse in LTE network.
    John , would you please help me going through it , I am stuck in Simulation . Your help would be pretty much needed.

    Thanks in Advance.

  11. Thanks John,

    I need one more help i m doing project on “Dynamic Spectrum allocation in Femto based LTE network”. I have completed the implementing the same. But now i need to do some changes to that. What changes can be done..?
    Pls help me its urgent

  12. Hello brothers
    I’m a student doing thesis in the area of Soft Frequency Reuse. How can I obtain the simulator codes of the paper “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks” it is very important to me please if any one can help me with this.

    Thanks so much in advance

  13. Hello brothers
    I’m a student doing thesis in the area of Soft Frequency Reuse. How can I obtain the simulator codes of the paper “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks” it is very important to me please if any one can help me with this.

    Thanks so much in advance

  14. I am doing M.tech final year project on spectrum allocation inside femto cell. The IEEE paper which I have selected is Dynamic Spectrum Allocation in femto based LTE network. Can any one tell whether I need to concentrate on LTE or femtocell. I m very much confused.

    Pls reply its very urgent

  15. Hello am doing a final year project on soft fractional frequency reuse in cognitive femto-cells in LTE. I really need to simlulate on matlab but I need the codes.

    Thanks in advance

  16. Does any body use LTE-Sim to simulate SFR or use matlab to simulate SFR ? what is the best way in terms of time and effort to simulate SFR ?

  17. SFR as explained in [1].
    “The soft frequency reuse (SFR) nowadays is considered as one of the most effective frequency planning strategies to mitigate inter-cell interference in cellular systems. It was first introduced in GSM, and then has been adopted under the 3GPP LTE framework with the aim of providing higher performance for users near the cell boundary. The basic idea of SFR is to apply a frequency reuse of one at the cell center area and a higher frequency reuse factor at the cell edge area. Rather than the hard frequency reuse (HFR, where reuse factor = 3) and fractional frequency reuse (FFR) schemes, SFR is able to reduce the inter-cell interference without largely sacrificing spectrum efficiency due to its lower reuse factor (nearly equal to one).

    In SFR, the available spectrum is divided into two reserved parts: a cell-edge band and a cell-center band. Users within each cell are also divided into two groups, cell-center users and cell-edge users, based on their distance to the base station or other differentiating factors. Cell-edge users are restricted to the reserved cell-edge band while cell-center users have exclusive access to the cell-center band and can also have access to the cell-edge band but with lower priority.”

  18. I’m a student doing thesis in the area of Soft Frequency Reuse. How can I obtain the simulator codes of the paper “Performance Analysis of Soft Frequency Reuse for Inter-cell Interference Coordination in LTE Networks” it is very important to me please if any one can help me with this.

    Thanks in advance

Leave a Reply

Your email address will not be published. Required fields are marked *