IEEE TRANSACTIONS ON BROADCASTING, VOL. 52, NO. 3, SEPTEMBER 2006 281 Design Procedures and Field Test Results of a Distributed-Translator Network, and a Case Study for an Application of Distributed-Transmission K. Salehian, Y. Wu, and B. Caron Abstract—This paper presents the implementation procedures and field test results of a Distributed-Transmission Network (also referred to as “DTx network” or “DTxN” throughout the paper) consisting of three coherent translators. As will be explained later in the text, a network of coherent translators, which is called “dis- tributed translator network”, is one of the three methods of im- plementing a DTxN. The performance of such distributed trans- lator network was tested in a strong static and dynamic multipath environment. The target area of the distributed-translator network under con- sideration was selected to be a small part of the coverage area of a distant single transmitter. This provided the possibility of taking the reception quality of the distance transmitter as a reference, and evaluating the reception quality of distributed-translator network in its target area. Two types of ATSC receivers, a new prototype and an older generation one, were used for this study. This in turn made it possible to compare the performance of the two receivers under tough conditions, and to investigate the impact of DTxN on the older generation receiver. As an application of the Distributed-Transmission Network, the possibility of changing a number of low-power (LP) existing DTV assignments into a DTxN was also investigated in a case study. The existing LP assignments, the candidates for changing into DTxN, were all part of a provincial network that is broadcasting the same program on different channels across the province of Ontario-Canada. Using DTxN can improve the quality of service of the LP assignments and reduce the spectrum congestion within the existing allotment plan. Index Terms—Distributed translator network, distributed trans- mission, distributed transmission network, distributed transmis- sion system, on-channel repeater, single frequency network. I. INTRODUCTION T HE ATSC recently approved “The Synchronization Stan- dard for Distributed Transmission” (ATSC A/110) [1] and a Recommended Practice on “The Design of Synchronized Mul- tiple Transmitter Networks” (ATSC RP A/111) [2]. According to RP A/111, Distributed-Transmission is a way of covering a big service area with a network of multiple transmitters, all syn- chronized and transmitting exactly the same program, but using far less number of channels than the number of the transmitters Manuscript received June 15, 2005; revised March 8, 2006. The authors are with the Communications Research Centre Canada (CRC), 3701 Carling Avenue, Ottawa, ON K2H 8S2, Canada (e-mail: khalil.salehian@crc.ca; yiyan.wu@crc.ca; bernard.caron@crc.ca). Color versions of Figs. 1–4 are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TBC.2006.879851 constituting the network. If the number of channels used by such a network is one, it forms a Single Frequency Network (SFN). As explained in the ATSC RP A/111, DTx networks have a number of benefits over the single central transmitter configu- ration, which has so far been the usual way of covering a large service area with analog TV transmission. The benefits include: • More uniform and higher average signal levels throughout the coverage area • More reliable indoor reception as a result of higher average signal levels, and possibility of receiving signal from more than one source. • Stronger signals at the edges of the service area without increasing interference to neighboring stations • Less overall effective radiated power (ERP) and/or antenna height resulting in less interference Technical and comprehensive explanations verifying all these benefits have been given in the Recommended Practice ATSC A/111 [2]. However, as a simple reasoning, one can consider the fact that in a single central transmitter configuration, the radiated power of the transmitter is designed to be high enough to pro- vide the required signal strength at the farthest edge of the cov- erage area. Under such circumstances, in locations closer to the transmitter, the signal strength is much more than that required for a satisfactory reception. Avoiding such unnecessarily high signal levels by using a number of lower power transmitters to distribute the transmission, a DTxN can provide more uniform and moderate signal levels across the service area while using less overall ERP and/or antenna heights. It should also be considered that the large amount of power, which is used by a single central transmitter to reach the far end of its coverage area, is radiated toward the neighboring areas. This causes the interference to extend much farther into the neighboring stations. However, such interference can be miti- gated by designing a DTxN made of some lower power trans- mitters that may be located closer to the edge of the coverage area and transmit more inward, rather than outward, to cover the same service area as the single transmitter [2]. By exploiting the possibilities provided by DTx network and its special instance, Single Frequency Network (SFN), the number of channels used to cover a large service area will be minimized. In this way, the spectrum could be saved and made available to other applications such as interactive TV, multimedia broadcasting, or any other future applications [3]. As a trade-off for these benefits, the implementation of a DTx network requires a very careful design when a DTV adjacent channel is operating in the same market area. Within-market 0018-9316/$20.00 © 2006 IEEE