How can I improve GPS accuracy in urban environments or areas with obstacles?

[DormantTree]

Hi I am considering the purchase of a gps with these requirements

 

[Nuvi-Nebie]

The more modern GPSs use not only GPS (USA) satellites but also GLONASS (Russia), Galileo (EU), Beidou (China) etc., using a combination of sattelite groups can achieve better results in urban environments