Industrial single-layer fabric having concave-convex surface

An industrial single-layer fabric having a concave-convex upper side surface and a lower side surface, which comprises warps, wefts and auxiliary wefts having a smaller diameter than the wefts:

• wherein, on the upper side surface in a repeating unit, at least two different upper side knuckles selected from first through sixth knuckles formed by the warps, each of the warps passes over one weft and zero to two auxiliary wefts;
• wherein, on the lower side surface in the repeating unit, at least two kinds of lower side knuckles are formed by the warps, each of the warps passes under one weft and zero to four auxiliary wefts;
• wherein, the wefts form a plain weave design by alternatively passing over one warp and passing under one warp;
• and
• wherein, the first knuckle is formed by one of the warps that successively passes over one weft and then one auxiliary weft which are adjacent to each other;
• the second knuckle is formed by one of the warps that successively passes over one auxiliary weft and then one weft which are adjacent to each other;
• the third knuckle is formed by one of the warps that successively passes over one weft and then two auxiliary wefts which are adjacent to one another;
• the fourth knuckle is formed by one of the warps that successively passes over two auxiliary wefts and then one weft which are adjacent to one another;
• the fifth knuckle is formed by one of the warps that successively passes over one auxiliary weft, then one weft and then one auxiliary weft which are adjacent to one another;
• and
• the sixth knuckle is formed by one of the warps that passes over one weft only.