SEQ) = K
2.4 Software especializado
Here arises an important question, “Are you ready to decant cellular operators in their networks exponential growth in data traffic?” The answer is no, because in general their transport networks (backhaul) are based on technologies and protocols that were designed for voice traffic. Importantly, the backhaul network is connecting access nodes to the backbone IP network.
Figure 92 - Backhaul Backbone and IP
The data transmission networks of the operators will have to reach eventually migrate to new technologies, which allow the growth of data traffic while maintaining the profitability of operators. This challenge can only be achieved with a transport
architecture that is efficient in data traffic, and that has a wide possibility of scalability.
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Do not forget also that the demand for voice services continues to grow, and network traffic increases not only the data but in the traditional services. Thus, it imposes a greater need to free up capacity on legacy networks, and to accommodate data traffic in the infrastructure of next generation based on IP / Ethernet that allows for growth by increasing costs marginally, to introduce technologies such as HSPA+ and LTE.
Among the major requirements to be met by a backhaul network to support LTE are:
• Increased capacity: 100 Mbps exceed its deployment
• Low Latency: must meet requirements of 10 ms for point to point
• Improved services: should point to point interface (S1) and multipoint interface (X2) efficiently
• Support services and legacy equipment
Moreover in the industry are shuffled some figures regarding the ability of each technology required for transport:
• HSPA supports 50 Mbps per sector
• HSPA+ up to 100 Mbps per sector
• LTE will support up to 170 Mbps per sector
More details of the Japanese manufacturer Fujitsu suggests that the capacity required per site is only the spectrum (channel size) available by the operator multiplied by the spectral efficiency of the air interface. The following figure summarizes these requirements for various wireless access technologies.
Technology
Figure 93 - Requirements for mobile network capacity
As shown, for a site with 3 sectors and a 5 MHz channel capacity will require about 40 Mbps, while for a 10 MHz channel will be 80 Mbps and thus the requirement will increase to reach 20 MHz channel that supports LTE.
7.6.1 Evolution LTE backhaul
Today the vast majority of operators have to transport TDM voice and data backhaul.
The option to keep adding E1 to provide more capacity becomes immediately feasible, since it would require a disproportionate amount of them to support traffic growth is anticipated in the future. Fortunately, industry and operators have identified the technologies to start migrating their transport networks in order to accommodate the growing traffic.
The future of transport networks of cellular operators offer goes through the Ethernet-based services and transport networks Ethernet-based on IP / MPLS and Carrier Ethernet, which lived for several years with the networks eventually replaced, as TDM, ATM, SDH / SONET and Frame Relay, which have been used to carry voice traffic and
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to offer Carrier Ethernet services. It seems that in future transport networks
accounting is themselves with a portion in the core IP / MPLS and other nearby base stations, based on Carrier Class Ethernet, which has attributes conducive to cellular backhaul, as for example:
The dilemma of the operators is, therefore, how to perform this migration while respecting the existing services that now account for most of the income, while
preparing its transport network to evolve its offering of data according to the expected growth is projected for the next three to four years.
For operators with large investments in TDM migration route is more feasible coexistence, at least initially, TDM to Ethernet networks, where networks would handle all existing TDM voice traffic while the data stream is transported over Ethernet . And is that even though it might seem that managing two networks simultaneously affects a high OPEX for the operators, the costs would be comparatively lower than more input E1 lines for greater data capacity.
And in the future transport networks will necessarily migrate to data transmission networks where Carrier Ethernet and IP / MPLS current bets seem to offer Ethernet-based services and emulate those Ethernet-based on legacy technologies. Strategically, cellular backhaul over Ethernet allows not only to offer services HSPA today, but leaves the transportation network ready for launch of HSPA+ and, above all, LTE which is an IP network from end to end and whose base stations have only Ethernet interfaces for transport tasks from the base station to the core of the operator's network.
7.6.2 Transport backhaul technologies LTE
To meet the transport capacity growing demand, the following technologies are evaluated, backhaul fiber and microwave backhaul ranges 6-38GHz and 60-80 GHz.
7.6.2.1 Optical fiber
Fiber is technically very good complement to the backhaul. With systems that can easily scale it beyond 10 Gbps, the fiber will solve any problem that may have
operators in terms of capacity requirements. The fiber can be deployed in redundant ring topologies, high-capacity but the infrastructure to do so can significantly increase costs. Finally, the fiber is capable of Synchronous Ethernet allowing the management of multiple service levels and providing synchronization LTE. Given these
capabilities, if the fiber has already been deployed and is available, is the perfect option for LTE backhaul.
7.6.2.2 Microwave
Traditionally, microwave (range 6-38GHz) have capacity constraints in a range between 150 and 300 Mbps, however, with new technological advances in the microwave field may give more than 1 Gbps and some systems up to 4 Gbps. There are still many versions of microwave systems available, with packages based on microwave technology commonly used for backhaul. For its part emerging microwave products are offered to distribute synchronization capabilities for LTE base stations.
Also, some of them are equipped with ring exchange capacity, ie allowing to set different ring architectures dynamically, with service capabilities high end
performance.
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7.6.2.3 Millimeter Wave Technology
Recently, some operators have begun to evaluate millimeter wave technologies for 4G backhaul. These products can generally meet the requirements of 4G capacity when most systems reach only 1 Gbps capacity. Many of these systems prioritization so that they can be multiple levels of service. 60-80 GHz systems do not currently provide Synchronous Ethernet capabilities but it is assumed that they probably will because the LTE deployments require. In economic terms, the costs of 60-80 GHz are quite similar to those of 6-38 GHz microwave
On the other hand, the greatest challenge millimeter wave systems is its availability and the resulting range of capabilities due to rain fade. Because these litters are at millimeter wave frequencies as high, are very susceptible to rain, resulting in limited sections of link in order to achieve reasonable capacity. It is also limited to less than two miles stretches.
Then noticed that there are several viable options to meet the requirements of backhaul and access networks is predicted, LTE network will use any one technology. Certainly there will be a mixture of two or more optimal network technologies driven by the location of the site and distribution sites. For new construction sites that require miles of range, shows a typical preference for
microwave technology from the perspective of cost and accessibility. However, in a large network find fiber in the central area where very high capacities are required and may be some millimeter wave technology in sectors where the scope permits.