LTE/SAE: The Next Step
Clear CinCom was one of the first radio consulting companies to offer consulting services for LTE/SAE networks. LTE (Long Term Evolution) and SAE (System Architecture Evolution) make up the next step in cellular radio networking, after 3G technologies such as UMTS. Thanks to simplified protocols and a flat, all-IP architecture, higher data rates and lower latency are achieved. This makes LTE ideally suited for all kinds of multimedia services, voice, video, mobile TV and internet data. LTE increases throughput and available bandwidth, reduces costs, and can be deployed on existing 3G infrastructure. It can even serve as an upgrade from other platforms such as CDMA.
Upgrade or leapfrog
LTE can be introduced cost-effectively by building on existing 3G networks, or it can be used to leapfrog from older or even different hardware. In case of an upgrade from an existing 3G network, proper configuration of base stations and antennas is a prerequisite and Clear CinCom can provide assistance.
In the downlink, the system is based on OFDMA, whereas in the uplink SC-FDMA is used. This results in a low latency network that is able to achieve data transfer speeds of 173 Mbps (download) and 58 Mbps (upload). LTE/SAE minimizes the need for BTS, CAPEX and OPEX and is therefore highly cost-efficient. No feeders are used, as only an optical and a power cable go up the tower. This means that no more feeder losses need to be suffered.
The optimal cell size of an LTE/SAE network is 5km, but this can easily be extended to 10km with reasonable performance, or up to 100km with minimal performance. Every 5Mhz allows for 200 active users.
This efficiency is achieved by:
- High radio bandwidth (20MHz instead of, for example, 5MHz)
- A flat, IP-based architecture, resulting in 2 instead of 4 network elements
- Built in IP backhaul
- BTS can be converted to eNB using only a software upgrade
Considerable performance gains can be achieved when using a MIMO (Multiple Input Multiple Output) setup. LTE accommodates four antennas on the mobile and four at the base station in a 4x4 MIMO configuration. LTE is also highly efficient at smaller bandwidths, making LTE/SAE the primary option for low frequency bandwidth refarming.
LTE/SAE is a crucial step in accommodating the growth of network traffic. HSPA can accommodate up to a 40-fold increase at the 900/2100 MHz bands, but only in moderately populated areas. Including LTE at the 1800/2600 MHz bands, a 40 fold increase is possible in even densely populated areas. Across all spectrum bands (900/2100/1800 and 2600 MHz) LTE can accommodate a 100-fold increase in traffic.
Because of the high demand for flexible spectrum usage, LTE uses diversified frequency bands (700 to 3600 MHz), varying bandwidth (1.4 to 20 Mhz), using the paired and unpaired spectrum (FDD and TDD). In itself, LTE/SAE is an evolution of 3G technologies, making optimal use of existing UTMS, EDGE or HSDPA ecosystems. However, interworking with non 3GPP radio access systems such as CDMA is provided, allowing CDMA centric providers to leapfrog in the evolution toward 4G technology.