Cellular technologies Evolution Toward 4G

First commercial mobile network prototypes appeared in the 60’s
In US Inporved Mobile Telephone Service system were used also in cars
- 25 Watts of transmtter power at the mobile station
- 100-250 Watts at the terminal
- Pure FDMA
- 40-60miles of BS coverage

Difficulties in implementation of the user equipment of normal size of weight
Coverage, Capacity, interference and other issues
Need to cover the whole world with a hundreds of properly designed radio transceivers and connect them to the control center.

1st Generation
- 1980s
- Standard: NMT, AMPS
- FDMA used to separate users
- Sectoring Techniques appeared on a base station side
- Not encrypted voice traffic
- FM- Used
- automatic switching (Dial)
2G and popularity
- 1990s
- GMS and IS-95
- TDMA and CDMA mechanism used to divide users
- FSK digital modulation is used
- Compression, multiplexing, codecs usgae
- A5/2 encryption (in GSM)
- SIM cards introducted in 2G(Carriers network - speicfic information)
- Growth of a number of subscribers
2G NON-commercial networks
- TETRA used by governement agencies, emergency serivies
- basic features of a standard
  - direct-mode operation (DMO) or using trunked-mode operation (TMO)
  - Call priorites
  - Group calls(1-to1, 1-to-many, many-to-many)
  - Relay communication
  - Call querying instead of blocking
2.5 - 3G Data transmission networks
- 2.5G
  - GPRS(General Packet Radio Service) up to 50kpbs
  - EDGE(Enhanced Data Rates for GSM Evolution) up to 250 kbps
- 2 domains
  - Circuit Switch(voice transmission)
  - Packet Switch (data transmission)
- 3G prioritized development of data transmission part
- 3G
  - UMTS (Universal Mobile Telecommunications System)
  - CDMA2000(2.5G to 3G world wide)
  - Applications
    - Moible TV, Video Conferencing….
  - Extensions (3.5-3.9G)
    - HSDPA, HSUPA, HSPA+, UMB
  - 1-2Mbps data rates

PHY and MAC improvements
CDMA advantage
- flexibility of resource usgae (high number of codes with different rates), not the capacity
- much more resistant to narrow band interference
- Connection to 2 more base stations at the same time is possible with one transcevier(different codes)

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WiMax and LTE main technology candidates
both more or less similar data rates, QoS and equipemnt price
WHY LTE
- need to replace all mobile phones when using WiMax
- Network Core itself is not needed anymore
4G LTE PHY and MAC
- MAC layer
  - OFDMA as an medium access mechanism
  - More improved flexibility of a resource usage
- PHY layer
  - Imporved antenna techniques such as MIMO
4G base station
- Reduced energy consumption
- Reduced size (more than 2 times)
- Reduced cost
- simplicity of replacement
4G user devices and applications
- Smartphones, Tablets
- Stream Video and video calls
- Online Gaming, cellular, location-based sevice
- Interference and capacity problems

Billy Chan