Frequency hopping CDMA

Frequency assignment and interference calculations in Frequency Hopping CDMA systems can be performed with ICS Telecom in two different ways:

• Translate the problem into a fixed frequency analysis.
• Consider frequency hopping with statistical and random analysis.

Fixed frequency analysis

The user has first to define the total spectrum that he intends to utilize in the system.
This spectrum can be made of a continuous band or split in different sub-bands.
Each sector is defined as a fixed frequency transmitter that can use at the same time only one frequency (channel) or multiple channels in the downlink.
The frequency assignment will give as a result the channels that can be simultaneously used in the global system, considering all RPUs. In fact, this has to be analysed as follow: this result is not directly a frequency assignment as each transmitter will use the whole spectrum allowed, but it gives the frequency or set of frequencies used at a given time. We can then consider that the result provides the best "starting point" of each sequence used by each sector and the best channel separation required between each couple of sectors.
If required, the spectrum band defined as an input can be modified by adding or removing frequencies to improve the results:

• Example:
  Spectrum used : F1, F2, F5, F6, F7, F8.
  In the InnoWave system, the delta frequency between Fi and Fi+1 is 1MHz.
  For example:
  F1 = 3405 MHz.
  F2 = 3406 MHz.
  F5 = 3409 MHz.
  F6 = 3410 MHz.
  F7 = 3411 MHz.
  F8 = 3412 MHz.
  
  
  
  This spectrum also defines the frequency hopping sequence used by each sector, alos called the "hopping set".
  5 sectors (mono channel) : BST1, BST2, BST3, BST4, BST5.
  Frequency assignment result :
  BST1 uses frequency F2.
  BST2 uses frequency F7.
  BST3 uses frequency F1.
  BST4 uses frequency F8.
  BST5 uses frequency F2.
  Analysis :
  The best solution is:
  BST1 uses "start index 2".
  BST2 uses "start index 5".
  BST3 uses "start index 1".
  BST4 uses "start index 6".
  BST5 uses "start index 2"
  
  Note : The multi-channel is an option that is not clearly defined in the InnoWave documentation.
  To be checked.
  The interference analysis can then be performed with the frequencies set after the assignment. Data required : (C/I) ratios required in cochannel, in adjacent channels and maybe N+/-2 channels.
  
  The Innowave documentation assumes that no interference problem is expected when the channel separation is 2MHz (2 channels).

Frequency hopping

ICS Telecom can also take into account frequency hopping transmitters and perform frequency assignment and interference calculations with these kind of stations. But in this case, we have to enter in a random mode that will take into account a probability of collision in time and probability of collision in frequency. In this case, the assignment can also choose the best starting index of each sequence.

Frequency hopping transmitter (parameter box):

Frequency hopping assignment including "Start index assignment":