Said Tatesh

LTE for public safety networks

It is increasingly being recognized that effective communications are key to a successful response to emergency and disaster situations. The ability of the first responder emergency services to communicate among themselves and to share multimedia information directly affects the ability to save lives. This is reflected in increasing public investment in broadband public safety communication systems. These systems have some specific requirements, which are outlined in this article. As LTE is expected to become the most widely deployed broadband communication technology, we examine the capability of LTE to meet these requirements, and identify possible future developments to LTE that could further enhance its ability to provide the necessary service.

Coexistence studies for 3GPP LTE with other mobile systems

To ensure LTE systems can coexist with other mobile systems operating in the same geographical area, or the LTE Base Station (BS) can be collocated with other mobile system BSs, coexistence studies for LTE with other systems have been carried out in 3GPP. In this article, we provide an overview of the coexistence studies that have been done. First we list the terminologies that are commonly used for coexistence studies, and explain how deterministic analysis can be done for the BS to BS interference scenario. Then we provide the system simulation methodology and assumptions used in the coexistence studies, and show some simulation results for the possible impacts with different system parameters. Finally we provide the references to the 3GPP standards where the LTE BS and UE radio transmission and reception requirements are specified to facilitate LTE coexistence with other mobile systems.

The long term evolution towards a new 3GPP ∗ air interface standard

The performance targets for the long term evolution (LTE) of the Universal Mobile Telecommunication System (UMTS) into a 4th generation system have been chosen to be very ambitious. While all of these targets may not be achievable in practice, they have served to motivate the decisions for a particular LTE design. Specifically, we discuss the choice of the multiple access scheme for LTE, provide details on the uplink and downlink transmission formats, analyze the benefits of multiple input multiple output (MIMO), and outline approaches for intercell interference mitigation. The trade-off between usage of MIMO spatial multiplexing and beamforming is shown for a practical system. The required signaling overhead is weighed against the performance improvements available from the additional information. Finally, some examples for the achievable physical layer performance are given.

Evolution of UMTS toward high-speed downlink packet access

An expanded effort is under way to support the evolution of the Universal Mobile Telecommunications System (UMTS) standard to meet the rapidly developing needs associated with wireless data applications. A new, shared channel — the high-speed downlink shared channel (HS-DSCH) — provides support to packet-switched high-speed data users. A number of performance-enhancing technologies are included in the high-speed downlink packet access (HSDPA) system to ensure high peak and average packet data rates while supporting circuit-switched voice and packet data on the same carrier. Lucent Technologies took a pivotal role in specifying many of these techniques, including adaptive modulation and coding (AMC), hybrid automatic repeat request (HARQ), and fat-pipe scheduling. In this paper, we provide system-level simulations results to indicate the achievable performance and capacity with these advanced technologies. We also discuss HSDPA protocol architecture along with the uplink and downlink control channel design and performance. We conclude with a discussion of potential enhancements for the future.