How many types of hopping are there?1. Frequency hopping 2. Antenna hoppingHow many types of frequency hopping are there?1. Base band2. SynthesizeHow does base band hopping work?In baseband hopping, each transmitter is assigned with a fixed frequency?

What is the advantage of baseband?What is C0 filling? Do we have to set C0 filling?What happens in Null filling? Disadvantage?Narrow band filter combiner can be used where more than 12 TRX can be used with almost no combiner loss. Hybrid combiner can be used as well. transmitter is automatically set up for c 0 filling.C0 filling is no power control and no DTX is used. Transmitter sends dummy burst cause MS measures on that frequency. Number of frequency is dependent on transmitter. Since 1 TRX transmit continuously the BCCH frequency with full power it might get weak after some time.

What is the advantage of Synthesizer? How do we have set C0 filling?Why we can not do Nul filling in Synth hopping? What happens in Null filling? Disadvantage?The advantage of this mode is that the number of frequencies that can be used for hopping is not dependent on the number of transmitters.C0 filling is not . 1. Either with extra transmitter when 3 TRX are used.2. Or by making 2 channel groups A transmitter configured for synthesizer hopping can not perform filling since it is not configured for a fixed frequency.Why do we use 2 channel groups?Since C0 filling is not possible in Synth hopping we use 2 channel groups so that in one channel group we dont use hopping in another channel group we use hopping.In case of any TRX fault which hopping gives more call drops for hardware failure?Synth hopping. Cause in synth hopping any subscriber is sticks to any particular TRXs TS. And he does not roam around all TRX like baseband. So as a result when any TRX is at fault the subscribers at that TRX cant hop to other TRX and call drops after RLINK timer expires.What is the relationship between MAIO and frequency list In HFS?The number of MAIO = number of frequency at best. But the number of MAIOs =number of TRX.What is the formula for using MAIO in cyclic hopping?

It starts with FN=1 so at starting (FN+MAIO)mod(No of freq)(1+0)mod(9)=1 so 0 MAIO will shift to 1 step below the starting freq. So at the beginning 4,12,21 will be transmitted. The next step (FN+0)mod9=1 so in the next step 0 MAIO will shift one step down word and will point to 7 so the freq transmitted will be 7,17,22. And so on.

What is FLP? Benefit? Which freq hopping is recommended? What is the draw back fo using synth hopping? During hopping which cell should we let serve at the cell border?FLP means that a cell hops over more frequencies than it has TRXs, i.e. that a frequency is only used a fraction of the time. FLP maximise the frequency diversity gain, since FLP allow hopping over a great number of frequencies. This leads to maximal coverage if the hopping channels are used at the cell border. Minimized frequency planning and flexible network expansion support, and High frequency utilization.

Random.The speech channels on the BCCH carrier do not benefit from frequency diversity, which yields a lower coverage performance. But in case of TCH channels the effect is reversed thats why during channel assignment TCH channel group should be given 1rst priority while tch assignement.

What is FL and HFL?FL = E/(TS/TRX x Freqs)

HFL = (HopTRX/site / 3)/Freqs

Where 1/1 is more suitable?1/1 is especially suited for new operators with modern equipment (hybrid combiners) and with narrow spectrum (less than 7 MHz).

During hopping which cell should we let serve at the cell border?Non hopping frequencies.What are the important factors that we should consider during FLP implementation?Basic tuning of handover performance (Locating)The tighter the frequency plan gets the more important it becomes to use signal strength ranking in locating, i.e. to be connected to the strongest server. This implies that it is recommended not to use offsets unless necessary. It is further recommended to use shorter filters, low penalties and so on in order to stick to the best server to a larger extent.

Power control feature usageBTS power control.For BTS power control the recommended setting is SSDESDL=90,LCOMPDL=5, QDESDL=30, QCOMPDL=57, UPDWNRATIO=300. Filtersshould be set short (to 3 SACCH periods).If the TCH carrier are in a blocked configuration, i.e. no BCCHs adjacent, it isbenefical to use a more aggressive setting compared to staggered TCH withadjacent TCHs-BCCHs, e.g. QCOMPDL=65.NOTE that it is recommended to only adjust the parameter QCOMPDL for thefine-tuning of the algorithm to keep control over different settings used.MS power control:For MS power control the recommended setting is SSDESDL=90,LCOMPDL=50-90, QDESDL=0, QCOMPDL=50-60.The signal strength filters should be set short (to 3-5 SACCH periods). Thequality filters needs to be a bit longer (to 4-8 SACCH periods) in order not tocreate an unstable situation.A more aggressive strategy for high signal strength mobiles should be used ifthe physical reuse is tight. This is controlled by means of the LCOMPULparameter and should be set to 50 (for reuse above 8, e.g. MRP), to 70-80(for 1/3 reuse) and to 80-90 (for 1/1 reuse).NOTE that it is recommended to only adjust the parameters SSDESUL andLCOMPUL for the fine-tuning of the algorithm.

DTXDiscontinuous Transmission (DTX) on the uplink is always recommended use since this feature gives better performance in most situations. Discontinuous Transmission (DTX) on the downlink should only be networks with tight frequency reuse and high load. This due to that tradeoff between quality and gain when using DTX on the downlink. benefits of the decreased interference are higher than the decreased accuracy of locating and the slightly worse speech quality, then this should be used. This has to be decided on a case by case basis on network performance and roadmap. In order not to have a large in handovers, the locating filter length can be adjusted to a slightly value, or the hysteresis can be set a bit higher, e.g. from 3 to 4.

Intra Cell HandoverIntra Cell Handover becomes a very useful feature in an FLP network since there are two channel groups with very different interference pattern in each cell. A proper analysis of whether uplink or downlink triggered events should be performed for BCCH and TCH channel groups. This might lead to that uplink triggered IHOs from the TCH to BCCH channel group is good to use and that downlink triggered IHOs from the BCCH to the TCH channel group is beneficial to use more aggressive.

What are the common mistakes done in the FLP?Absence of proper cell planthere should be a flat terrain with low and even antenna height. All sites should be on a good grid with no areas with bad coverage or lack of a dominant server. There should be no high-rise buildings with elevated traffic. (traffic generated above the clutter).On the other hand, in networks where cells with connections that makes handovers to many other cells and thus interfere with many different neighbours characterise a bad or difficult cell plan. The quality of a radio network with such a cell plan will suffer from a higher level of interference for a given traffic. The network will therefore have a significantly lower capacity.

The RXQUAL measure change behavior

RXQUAL must be interpreted and evaluated differently in a BB hopping, non-hopping or a SYhopping environment. There are two reasons to the change in RXQUALbehaviour:

1. Basically that fewer calls have RXQUAL 0 because of interference averaging. This yields that the RXQUAL distribution will look much worse just by turning hopping on. Also note that itis easy to stay connected at RXQUAL 5, 6 and 7 when hopping over many frequencies. In a non-hopping case its very probable to drop the call. This implies that the number of RXQUAL 5-6-7s increase in the case of hopping due to this phenomenon which gives a higher RXQUAL average. NOTE that the speech quality still is acceptable with RXQUAL 5-6 (and even 7 during short periods) when SY hopping over many frequencies.

2. The RXQUAL distribution will change when using FLP and thus the average RXQUAL. This will introduce a higher ratio of intra-cell handovers and bad quality handovers. Thus, the levels for the quality-triggered events such as Intra-cell handover and bad quality handovers have to be adjusted. Note thatthe subscriber perceived quality do not degrade because of the increased number of quality triggered events.