OL-Cesium improve tileWMS quality in very high zoom level

I’m developing an application which is based on OpenLayers v6.5.0. OL-Cesium 2.11, Cesium v.177 and GeoServer v2.17. The scale of the map view is very large. The camera height is only 20 meters. I use tileWMS layers and their quality is not so good. The tiles are blurried.

The code in OL:

        var wmsLayer = new ol.layer.Tile({
    visible: true,
    source: new ol.source.TileWMS({
      url: 'http://localhost:8080/geoserver/work/wms',
      params: {'FORMAT': 'image/png', 
               'VERSION': '1.1.1',
               tiled: true,
            "STYLES": '',
            "LAYERS": 'work:sample_polygons',
            "exceptions": 'application/vnd.ogc.se_inimage',
         tilesOrigin: -4.47449493408203 + "," + 42.4401245117188
      }
    })
  });

I tried to change the interpolation method in GeoServer, but without any results.

Is it possible to get better quality? Do you ahve any suggestions to improve the visibility? I also tried with WFS, but it’s very slow. The view will be changed often (like a car navigation), so the performance is very important.