With growing demand of very high data rates on both uplink and downlink, it is required that the backhaul networks laid for the interconnection between cell sites and base stations must be strong enough to handle such abundant traffic. LTE is supposedly going to offer minimum of 100 Mbps downstream and 50 Mbps upstream and maximum up to 1Gbps downlink, which is a huge figure when compared to current rates offered by the present technologies.
The Wireless backhaul network constitutes mainly of Node Bs (eNB) and LTE-Gateways (S-GW) or Mobility Management Entities (MME) between which the interconnection and transfer of high data rates would take place. 'S1' represents the direct connectivity between LTE eNBs and MMEs, and 'X2' represents the interconnectivity within the LTE eNBs.
Requirements for Wireless Backhaul networks:
High data rates: The transfer of data for uplink and downlink takes place between eNBs and MMEs. Very high data rates of minimum 100/50 Mbps DL/UL and maximum 1Gbps downlink would take place. Since, LTE is an enhanced technology, requirements of these high speeds are mandatory and so is the necessity to built a powerful network architecture to handle such enormous rates.
Flat architecture: An IP-based flat architecture is required, which must interconnect LTE eNBs and MME/S-GWs using multipoint connection architecture.
Low latency: Latency less than 5 msec is ideal for LTE networks.
Connectivity: Interconnections between entities in the backhaul network is the most important criteria, without which data cannot be transferred within entities and hence to the users. Point-to-Point, Point-to-Multipoint, Multipoint-to-Multipoint connections are done to set up the backbone of the LTE architecture.
Quality of Service (QoS): QoS is certainly a major aspect as providing services at high data rates would hinder the quality of services provided by the technology.
Briefly learning the LTE backhaul requirements, the task would seem to be easy, but that is not the case. Following these protocols and creating a strong base for LTE requires great precision and commitment by the deployers.
Reference
"Wireless backhaul for LTE - requirements, challenges and options", Venkatesan, G.K.; Kulkarni, K.;
Advanced Networks and Telecommunication Systems, 2008. ANTS '08. 2nd International Symposium on, Digital Object Identifier 10.1109/ANTS.2008.4937790