Antenna Hopping
INTRODUCTION
› Sometimes it so happens that while in a dedicated mode a MS falls in the fading
dip of the received signal....
AREA OF IMPLEMENTATION……
› In the channels which doesnot have frequency hopping
(e.g. BCCH).
› It is used for traffic chan...
Advantages of Antenna Hopping
› It can be used without increasing the number of TRXs in
a base station.
› More robust radi...
WORKING PRINCIPLE OF ANTENNA
HOPPING
The combinations of the same signal from two different transmit paths
results in aver...
ANTENNA vs FREQUENCY
HOPPING
ANTENNA
HOPPING
With antenna
hopping and no
frequency hopping,
the same interference
is prese...
EFFECTS ON CODECS
› GAINERS
EFR, AMR, GPRS CS1 and CS2 as well as EGPRS
MCS-1, MCS-2, MCS-5 and MCS-6.
› SUFFERERS
EGPRS M...
ANTENNA HOPPING--
A SPECIAL CASE
› PROBLEM
This technique of altering antenna on every burst is not
going to work in case ...
REQUISITES OF ANTENNA HOPPING
› An antenna hopping enabled configuration needs two
transmit antennas or a dual-polarized a...
ALGORITHM USED IN
ANTENNA HOPPING
› Antenna hopping is started on each Antenna Hopping
Set(AHS) when the AHSs has been cre...
ANTENNA HOPPING GAIN
› The gain from Antenna Hopping depends on
1. Propagation Environment,
2. Signal Strength,
3. Number ...
ANTENNA HOPPING GAIN contd….
› The following table can be used as an approximation for
the expected gain from antenna hopp...
A CASE STUDY ON EFFECTS OF
ANTENNA HOPPING
CONCLUSION
› Thus Antenna Hopping is a great feature to work with
which will help us improve the signal strength at any
po...
Antenna hopping
Antenna hopping
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Antenna hopping

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Antenna hopping

  1. 1. Antenna Hopping
  2. 2. INTRODUCTION › Sometimes it so happens that while in a dedicated mode a MS falls in the fading dip of the received signal.Then there is a high probability of the call getting disconnected.So in order to overcome this problem you have to transmit the signal over different paths.This means introducing diversity in the transmit path.This can be done using ANTENNA HOPPING. With antenna hopping, transmit diversity is introduced by altering transmit antenna between bursts.
  3. 3. AREA OF IMPLEMENTATION…… › In the channels which doesnot have frequency hopping (e.g. BCCH). › It is used for traffic channels with frequency hopping over a relatively low number of frequencies (less than 8). › This feature brings about a considerable amount of signal strength improvement in slow/non-moving mobiles than the fast moving mobiles.
  4. 4. Advantages of Antenna Hopping › It can be used without increasing the number of TRXs in a base station. › More robust radio environment. › Improved signaling performance. › Possibility to give subscribers a more uniform speech quality. › It can also be used along with Frequency Hopping.
  5. 5. WORKING PRINCIPLE OF ANTENNA HOPPING The combinations of the same signal from two different transmit paths results in averaging out their fading dips at any particular distance and thus helps us to get a fairly uniform signal strength at any point.
  6. 6. ANTENNA vs FREQUENCY HOPPING ANTENNA HOPPING With antenna hopping and no frequency hopping, the same interference is present in all bursts.This means that only the fast fading changes between the bursts resulting in only averaging out the fading dips of that signal at any point. FREQUENCY HOPPING In it a mobile is interfered by different base stations in different bursts, i.e. “interference diversity”.Thus results in averaging out the interference of that channel from other channels.
  7. 7. EFFECTS ON CODECS › GAINERS EFR, AMR, GPRS CS1 and CS2 as well as EGPRS MCS-1, MCS-2, MCS-5 and MCS-6. › SUFFERERS EGPRS MCS-4 and MCS–9. › NO EFFECT MCS-3, MCS-7 and MCS-8.
  8. 8. ANTENNA HOPPING-- A SPECIAL CASE › PROBLEM This technique of altering antenna on every burst is not going to work in case of HR channels as this would result in no transmit diversity in a two antenna configuration. › SOLUTION By transmission of the first two bursts via the first antenna and the next two bursts via the second antenna and so on, the antenna hopping gain will be achieved for half rate channels as well.
  9. 9. REQUISITES OF ANTENNA HOPPING › An antenna hopping enabled configuration needs two transmit antennas or a dual-polarized antenna in at least one antenna system. › Antenna Hopping can be enabled in a TG and not sectorwise. › It is of importance that all antennas in a cell are pointing in the same direction otherwise the measured average signal strength will decrease which may cause change of cell borders as shown in the next slide.
  10. 10. ALGORITHM USED IN ANTENNA HOPPING › Antenna hopping is started on each Antenna Hopping Set(AHS) when the AHSs has been created.The hopping is performed such that the following pattern is achieved: • Target antenna = (FN + (FN DIV 2)) MOD 2, if the number of antennas is two. Note: This pattern is selected to achieve transmit diversity gain even for half rate channels, where the channel is sent every second burst • Target antenna = FN MOD Nant, if the number of antennas is three or more. where FN = Frame Number and Nant = number of antennas.
  11. 11. ANTENNA HOPPING GAIN › The gain from Antenna Hopping depends on 1. Propagation Environment, 2. Signal Strength, 3. Number of antenna to hop on, 4. Number of hopping frequencies,& 5. Interference Characteristics.
  12. 12. ANTENNA HOPPING GAIN contd…. › The following table can be used as an approximation for the expected gain from antenna hopping in a typical urban (TU) environment. The expected gain in other environments may be smaller.
  13. 13. A CASE STUDY ON EFFECTS OF ANTENNA HOPPING
  14. 14. CONCLUSION › Thus Antenna Hopping is a great feature to work with which will help us improve the signal strength at any point by averaging out the fading dips at that point.This feature makes use of the transmit diversity. › There is a cellwise parameter AHOP which turns this feature ON or OFF.The settings of this parameter is as below.

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