In-building data-over-voice Internet access

High speed Internet access is becoming an essential service in the workplace which often includes hotels. This paper investigates short-range Internet access methods suitable for hotels, hospitals, and historic office buildings where pervasive telephone service exists and there is a need for "always on" high speed Internet access. It is desirable to avoid the costly installation of new wires to provide this service. While digital subscriber line technologies have matured over the last decade, and these are more than capable of providing the required service, their cost is excessive, and when transmission distances are very short there is an opportunity to apply lower-cost data-over-voice solutions. This paper evaluates the suitability of various baseband line coding techniques for data transmission in a simultaneous voice and data environment. Through computer simulation, a number of potential line coding methods were characterized by their power spectral density and eye diagram. These characterizations were used to evaluate data transmission capacity, error performance and potential interference with voice communication. The paper shows that bipolar-return to zero (BPRZ) and bipolar-non return to zero (BPNRZ) ternary coding provide the greatest potential improvement in data transmission rate while sacrificing the least in transmission performance. Quaternary and pentary methods are shown to be poor, and 2B1Q coding (widely used in ISDN and HDSL) is not applicable for data-over-voice since low frequency data transmission is required.