LTE (Long Term Evolution), introduced as 3GPP Release 8, was the first specification that offered next-generation mobile broadband capabilities. LTE-Advanced (Release 10) is the first true 4G technology to be specified by 3GPP.
compared with 3G standards, the main advances associated with LTE include high spectral efficiency, high peak data rates, shorter round-trip time and IP protocol for transport of both real-time and data services. LTE/LTE-A combine OFDMA (Orthogonal Frequency Division Multiple Access) with higher order 64 QAM modulation, expanded 20 MHz bandwidths and up to 4x4 MIMO spatial multiplexing to achieve higher peak data transmission rate of 75 Mbps in the uplink and up to 300 Mbps in the downlink.
A distinct feature of LTE is the absence of a centralized Radio Network Controller (RNC) as in previous mobile generations. LTE has adopted a flat architecture with a distributed network of “intelligent” base stations or evolved NodeBs (eNBs) to speed up connection set-up time and to significantly lower inter-eNB handover time especially for advanced real-time applications such as multiplayer gaming sessions. The eNBs are inter-connected via the X2-interface and connect to the core network via the S1-interface. The emergence of LTE/LTE-A is driving higher bandwidth requirement in the backhaul region. It is estimated that the bandwidth requirement for backhauling LTE-A is over six times that for LTE, and nearly 100 times higher than for 3G. Besides capacity, 4G/LTE also requires enhanced flexibility in handling data and control plane traffic over X2 and S1 interfaces with stringent time and phase synchronization for mission-critical services and to deliver high-fidelity video streaming services.
For incumbent 2G or 2G+3G operators planning to launch 4G/LTE services, Tejas converged packet optical (CPO) products are designed to achieve a pragmatic three-phase transition path whereby investments in backhaul upgrades are made in line with the observed growth in packet-based revenues. It starts with an optimization of existing transport infrastructure for hybrid voice and data carriage, followed by a cost-effective packet-overlay phase and eventually migrating to “all-packet” fiber transport architecture with voice itself being delivered as a packet application (e.g., VoLTE). For greenfield rollouts of 4G/LTE, Tejas packet transport networking (PTN) products can be deployed from day one support high-capacity circuit emulation over pure-packet backhaul networks that also maintain accurate synchronization information for these circuits. In the absence of a circuit-based network, timing delivery and transport to the LTE eNBs are critical requirements along with low latency and jitter for reliable TDM transmission. Tejas PTN products have field-proven implementations of structure agnostic/structure aware circuit emulation technologies (SAToP, CESoPSN), packet synchronization (SyncE/1588v2) and sub-50ms packet ring/line/path/tunnel protection to achieve these stringent service requirements.
Tejas CPO and PTN products are also integrated with LTE Access Controller (LAC) cards that are compliant to 3GPP Release 10 standards. The LAC card can act as a coordinated 3-sector LTE eNB or as three independently deployed single-sector eNBs with configuration flexibility in the MIMO order, carrier bandwidths and carrier aggregation options. Cell sites with fibre backhaul can seamlessly integrate transport and LTE access for superior end-to-end LTE performance and the added benefit of unified OAM, space and power savings. The telecom operator can create customizable scheduling profiles to optimize and prioritize throughput, latency, coverage or capacity on a per cell basis. 4G/LTE LAC cards are available on both TJ1400 and TJ1600 platforms.