3.9 Traffic Estimation Per User

Another factor with a major impact on the capacity required in today’s and tomorrow’s cellular wireless network is how much data will be transferred per user per day or month. The cost of transferring data over a cellular wireless network will certainly be the main tool for network operators to steer usage to a certain extent, as will be further discussed later on in this chapter. For current pricing strategies the following example shows the amount of data generated by a typical notebook usage of an office worker.

When away from the office, an average office worker generates about 70 Mbytes of traffic in about 10 h, mostly in the downlink direction. This includes e-mail, Web browsing, company database access and VoIP. For this example, it is assumed that about 50 Mbytes are received in the downlink and 20 Mbytes are transmitted to the network. The following discussion focuses on the downlink only. The average data rate over time is 1.39 kbyte/s (50 000 kbytes/s/10 h/60 min/60 s). Compared with the HSDPA cell bandwidth of about 300 kbytes/s (about 2.5 Mbit/s), as shown in Table 3.4, this is not much and more than 200 other subscribers with the same amount of traffic could use the same cell simultaneously. This calculation, however, is just as theoretical as assuming that all users will mostly use high-bandwidth video streaming applications. Thus, a capacity requirement calculation needs to take a number of other variables into account.