Comparison of Wireless Data Standards - Peak Bit Rate and Throughput

Peak Bit Rate and Throughput

When discussing throughput, there is often a distinction between the peak data rate of the physical layer, the theoretical maximum data throughput and typical throughput.

The peak bit rate of the standard is the net bit rate provided by the physical layer in the fastest transmission mode (using the fastest modulation scheme and error code), excluding forward error correction coding and other physical layer overhead.

The theoretical maximum throughput for end user is clearly lower than the peak data rate due to higher layer overheads. Even this is never possible to achieve unless the test is done under perfect laboratory conditions.

The typical throughput is what users have experienced most of the time when well within the usable range to the base station. The typical throughput is hard to measure, and depends on many protocol issues such as transmission schemes (slower schemes are used at longer distance from the access point due to better redundancy), packet retransmissions and packet size. The typical throughput is often even lower because of other traffic sharing the same network or cell, interference or even the fixed line capacity from the base station onwards being limited.

Note that these figures cannot be used to predict the performance of any given standard in any given environment, but rather as benchmarks against which actual experience might be compared.

• Downlink is the throughput from the base station to the user handset or computer.
• Uplink is the throughput from the user handset or computer to the base station.
• Range is the maximum range possible to receive data at 25% of the typical rate.