4G Objective

Before studying the objectives of 4G, let us understand some of the characteristics of 4G, which are summarized here in table 1.

Table 1: Characteristics of 4G 

Achievable Data Rates	10 Mbps (wide coverage) to 1 Gbps (local area). These are design targets and represent cell overall throughput.
Networking	All-IP network (access and core networks). Plug & Access network architecture. An equal opportunity network of networks.
Ubiquitous	Mobile, seamless communications.
Cost Reduction	Cost per bit: 1/10-1/100 lower than 3G Infrastructure cost-1/10 lower than 3G.
Connected Abilities	Person to person communication Person to Machine communication/Machine to machine communication.

The objective of 4G is to cater the quality of service and rate requirements set by the forthcoming applications like wireless broadband access, Multimedia Messaging Service, video chat, mobile TV, High definition TV content, DVB and minimal service like voice and data at anytime and anywhere 4G is being developed, the 4G working groups have defined the following as the objectives of the 4G wireless communication standard.

• Spectrally efficient system (in bits/s/Hz and bit/s/Hz/site)
• High network capacity, 10 times higher than 3G
• Nominal data rate of 100 Mbps at high speeds and 1 Gbps at stationary conditions as defined by the ITU-R
• Data rate of at least 100 Mbps between any two points in the world
• Smooth handoff across heterogeneous network
• Seamless connectivity and global roaming across multiple networks i.e. seamless services with fixed NW (Net Work) and private
• High quality of service for next generation multimedia support (real time audio, high speed data, High-Definition Television (HDTV) video content, mobile TV, etc)
• Higher frequencies: Microwave: 3-10 GHz
• Interoperable with the existing wireless standards
• All IP system, packet switched network
• Next-generation Internet support: IPV6, QoS, MoIP (Mobile over IP)
• Lower system costs: 1/10 of IMT-2000

In summary, the 4G system should dynamically share and utilize the network resource to meet the minimal requirements of all the 4G enabled users. Figure 1 illustrates here a prospective view of physical layer of 4G.

Figure 1: Prospective physical layer of 4G

 

Key Parameters

The move to 4G is complicated by attempts to standardize on a single 3G protocol. Without a single standard on which to built, designers face significant additional challenges.

Table 2 compares some of the key parameters of 3G and 4G. Though 4G does not have any solid specification as of yet, it is clear that some standardization is in order.

Table 2: Comparison of key parameters of 3G and 4G 

Key Parameters	3G	4G
Frequency Band	1.8-2.5 GHz	2-8 Ghz
Bandwidth	5-20 MHz	5-20 MHz
Data Rate	Upto 2 Mbps	Upto 20 Mbps
Access	W-CDMA	MC-CDMA or OFDM (TDMA)
Forward Error Correction	Convolutional Rate	Concatenated coding scheme
Switching	Circuit/Packet	Packet
Mobile Top Speeds	200 km/h	200 km/h
Component Design	Optimized antenna design, multi-band adapters	Smarter Antennas, software multiband and wideband radios
IP	A number of air link protocols, including IP 5.0	All IP (IP6.0)

4G Network Requirement

From above it is clear that 4G is immensely complicated and hence there will be special requirement for future networks. Some of these tentative requirements are hereby summarized in table 3.

Table 3: Requirement for future networks (tentative) 

Media	Transmission speed	Delay	Connection Latency	Terminal capabilities
Speech/3D Audio	< 1 Mbps	< 50ms	< 1 sec	3D sound field control High efficiency loud speakers
Video/3D video	10 Mbps (2D video) - 30 Gbps (3D video)	< 50ms	< 1 sec	Real time hologram
Enhanced Reality	< 1 Mbps	≪ 50 ms Should be predictable	N/A	Eyeglass display 3D and multimodal UI
Five senses communications	< 1 Mbps	< 50ms	N/A	Five sense sensors
Tele-existence	< 10Mbps (Robotic I/F) < 1 Gbps (Virtual avatar) < 100 Mbps (Alter-ego existence)	< 10 ms < 30ms < 5 ms (Small and known jitter)	1 Sec	Alter-ego robot

Development of 4G

There are many phases of developing 4G mobile communication systems. Let us study here two phases, i.e. development period and maturity period, which are described in table 4.

Table 4: Stepwise development of 4G mobile communications 

4G Mobile Communications
	Phase 1 (2009-2010): Developmental Period	Phase 2 (2011): Maturity Period
Core cellular systems	3.5G 3.5G mobile-communications system enhancing IMT-2000 (HSDPA/1xEV-DV)	4G 4G Mobile-communications systems
Transmission speed	30 Mbps	50 Mbps-100 Mbps
Service level	High-level application service	Service with higher-level authentication and security
Main users	Advanced users	General users
Functions	Basic functions	Fully-fledged system
Seam-lessness with other systems	Flexible realization of seamlessness with other systems	Seamlessness with no awareness thereof
Social impact	Positioning with social functions	Positioning as a factor inducing changes in social structure.

The Goal of 4G

4G must be clearly more than 3G in terms of services, applications, and technology. As a comparison, 4G is not a combination of High Speed Uplink/Downlink Packet Access (HSUPA/HSDPA) or Wireless LAN (WLAN).

3G networks are inadequate to accommodate WLANs as access networks, which offer data rates of 11 Mbps. The goal of 4G will be to replace the entire core of cellular networks with a single worldwide cellular network completely standardized based on the IP for video, Voice over IP (VoIP) and multimedia services. The newly standardized networks would provide uniform video, voice, and data services to the cellular handset or handheld Internet appliance, based entirely on IP. As 4G standards are not defined so there is plenty of room for other applications to overlap into the 4G space.

The 4G providers of advanced cellular technology are adopting Concatenated Coding which has the capability of providing multiple Quality of Service (QoS) levels. forward error correction (FEC) coding adds redundancy to a transmitted coded signal through encoding prior to transmission. A major advantage of Concatenated Coding over the Convolution Coding method will be an improved network performance by the combining of two or more coding techniques, such as a Reed-Solomon and a Convolution Code into one Concatenated Code. The combination improves error correction combining with error detection. FEC using Concatenated Coding allows a wireless network to send much larger blocks of data while reducing bit-error rate, thereby increasing the overall through-put.

The primary goal of the planned 4G cellular services will include: Interactive Multimedia, Voice, Video Streaming, High Speed Global Internet Access. Virtual Private Network (VPN) Availability, Service Portability with Scalable Mobile Services, High Speed, High Capacity, Low Cost Services, Improved Information Security, QoS Enhancements, Multi-Hop Networking.

Table 1 compares here various Wireless Communication Technologies.

Table 1: Comparison of wireless communication technologies 

	1G	2G	2.5G	3G	4G
Transmission	Analog	Digital	Digital	Digital	Digital
Architecture		Circuit Switch	Packed-Switch	Circuit and Packet Switch	Packet Switch
Speeds		9.6 to 14.4 Kbits/s	64 to 144 Kbits/s	384 Kbits/s to 2 Mbits/s	100 Mbits/s to 1000 Mbits/s
Standards	AMPS	TDMA, CDMA, GSM	GPRS, EDGE, 1×RTT	WCDMA, CDMA-2000	Single unified standard
Service	Mobile telephony (voice)	Digital voice, short messaging	Higher capacity, packetized data	Integrated high quality audio, video and data	Dynamic information access, wearable devices
Multiplexing	FDMA	TDMA, CDMA	TDMA, CDMA	CDMA	CDMA
Core Network	PSTN	PSTN	PSTN and Packet network	Packet network	Internet
Handoff	Horizontal	Horizontal	Horizontal	Horizontal	Horizontal and Vertical