The telecom consultants with unique expertise in GSM-R and indoor coverage network design

LTE/SAE: The Next Step

Radio telecom consultancy Clear CinCom announces to offer consulting services for LTE/SAE networks. It is one of the first telecom consultancy firms to do so.

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.

LTE/SAE, a standard set by the 3GPP, provides an answer to the problems facing network operators today: exploding mobile traffic and rising costs. With an unrivaled cost/performance ratio and a superior user experience, some 90% of the world's radio access market is expected to eventually migrate to LTE. Many large operators, including NTT DoCoMo, AT&T, Verizon and Vodafone, have already announced their switch.

Upgrade or leapfrog

LTE/SAE 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. Here Clear CinCom can provide assistance. Where no UTMS network has been established, GSM 900 sites and antennas can be re-used to provide LTE on the 900Mhz band. This is particularly useful for those seeking to upgrade an existing CDMA or GSM-R network.

Cost-efficient network

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.

Traffic growth

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.

Railway networks

LTE/SAE is designed for full mobility and is optimized for IP traffic. Speed and reliability make LTE/SAE clearly the most promising technique for the future of GSM-R and other mission critical networks. The UIC is currently working on the railway standards and specifications for dedicated LTE/SAE networks in railway environments. In real world testing, data rates of 50Mbps have already been established at a travelling speed of 110 km/h.

The future

In 2008, various telecom equipment vendors conducted a series of tests that showed that LTE/SAE can already meet the design goals formulated by the 3GPP. Depending on the scenario, cells were able to reach an average L1 throughput of 20 to 60 Mbps in an early real world test setup. The first commercial LTE devices are expected to enter the market 2010. Meanwhile, specifications for the next step in the evolution, advanced LTE, are being discussed. Advanced LTE, building on LTE/SAE standards, is set to establish download rates of 1Gbps.

The role of Nokia Siemens Networks as an LTE/SAE pioneer, already provides a complete LTE/SAE start-to-finish solution. As a Radio Network Planning supplier of Nokia Siemens Networks, Clear CinCom is fully conversant on the development of LTE/SAE from the onset. We can advise network operators as they prepare the move to LTE and optimize their hardware and software specifically for this purpose. We can also design, validate and optimize the final LTE/SAE network setup.

As the telecommunication consultancy with the most experience in GSM-R, Clear CinCom is in an ideal position to assist railway companies in the evolution from existing GSM-R platforms to the new LTE/SAE setup. By skipping current 3G technologies, railway companies can increase speed, throughput and reliability, while reducing overall network costs.