Elements of a wireless network
                                                                                wireless hosts
                                                                                 laptop, PDA, IP phone
                                                                                 run applications
                                                                                 may be stationary (non-mobile) 
                                                                                     or mobile
                                                        network                        wireless does not always 
                                                     infrastructure                       mean mobility
                                                                                            Wireless, Mobile Networks   6-2
         Elements of a wireless network
                                                                                base station
                                                                                typically connected to wired 
                                                                                    network
                                                                                relay - responsible for 
                                                                                    sending packets between 
                                                                                    wired network and wireless 
                                                        network                     host(s) in its “area”
                                                     infrastructure                    e.g., cell towers,  802.11 
                                                                                          access points 
                                                                                            Wireless, Mobile Networks   6-3
         Elements of a wireless network
                                                                                wireless link
                                                                                typically used to connect 
                                                                                    mobile(s) to base station
                                                                                also used as backbone link 
                                                                                multiple access protocol 
                                                        network                     coordinates link access 
                                                                                various data rates, 
                                                     infrastructure                 transmission distance
                                                                                            Wireless, Mobile Networks   6-4
   Characteristics of selected wireless link  standards
            200           802.11n
         )   54           802.11a,g                         802.11a,g point-to-point                             data
         s
         p 5-11           802.11b
         b                                                              802.16 (WiMAX)
         M
         (                                                                                                    3G cellular
               4                           UMTS/WCDMA-HSPDA, CDMA2000-1xEVDO
         e
         t                                                                                                     enhanced
         a
         r     1      802.15
          
         a
         t
         a
         D
           .384                                      UMTS/WCDMA, CDMA2000                                     3G
           .056                                          IS-95, CDMA, GSM                                     2G
                          Indoor               Outdoor              Mid-range            Long-range
                          10-30m                50-200m              outdoor               outdoor
                                                                   200m – 4 Km           5Km – 20 Km
                                                                                            Wireless, Mobile Networks   6-5
         Elements of a wireless network
                                                                                infrastructure mode
                                                                                base station connects mobiles 
                                                                                    to wired network
                                                                                handoff: mobile changes base 
                                                                                    station providing connection 
                                                                                    to wired network
                                                        network 
                                                     infrastructure
                                                                                            Wireless, Mobile Networks   6-6