Jun Tan

Bio: Jun Tan is an academic researcher from Motorola. The author has contributed to research in topics: Telecommunications link & Frequency domain. The author has an hindex of 6, co-authored 15 publications receiving 304 citations.

Preamble sequencing for random access channel in a communication system

Abstract: A system and method for initializing a system communication without previous reservations for random access channel (RACH) access includes a first step of defining at least one spread sequence derived from at least one constant amplitude zero autocorrelation sequence. A next step includes combining the spread sequence with a Walsh code to form an extended spread sequence. A next step includes using the extended spread sequence in a preamble for a RACH. A next step includes sending the preamble to a BTS for acquisition. A next step includes monitoring for a positive acquisition indicator from the BTS. A next step includes scheduling the sending of a RACH message. A next step includes sending the RACH message.

Random Access Design for UMTS Air-Interface Evolution

Abstract: Comprehensive long term evolution of the Universal Mobile Telecommunications System (UMTS) specifications is currently ongoing to provide significant improvement over the current release. Important goals for the evolved system include significantly improved system capacity and coverage, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration with existing systems. To ensure low latency, users must be able to establish a connection to the network quickly. This paper provides a preliminary design and procedure for the random access channel used to establish a connection when the mobile is not yet time-synchronized to the network in the uplink.

Mobile assisted downlink beamforming with antenna weight feedback

Abstract: A subscriber unit (104) with multiple receive antennas (160, 162) and a single transmit antenna (160) derives beamforming weights to be used at a base station (102) with multiple transmitting antennas (602, 604, 606, and 608). The downlink beamforming weights are derived at the subscriber unit (104) from a prior downlink transmission from the base station (102) to the subscriber device (104) and an uplink sounding signal is used to carry derived downlink beam forming weights to the base station (102). Downlink antenna specific pilots (without weight) are used at the subscriber device (104) to determine the beamforming weights. Decimated sounding signals, where the number of sounding subcarriers is al least the same as the number of antennas at the base station (102), allow multiple users to sound at the same time.

Overview of UMTS Air-Interface Evolution

Abstract: With the emergence of packet-based wireless broadband systems such as 802.16e, it is evident that a comprehensive evolution of the universal mobile telecommunications system specifications is required to remain competitive. As a result, work has begun on long term evolution (LTE) of the UMTS terrestrial radio access and radio access network aimed for commercial deployment in 2010. Goals for the evolved system include support for improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operations and seamless integration with existing systems. To reach these goals, a new design for the air interface is envisioned. This paper provides a preliminary look at the air interface for Evolved UTRA (E-UTRA) and associated key technologies required to reach its design objectives. Initial E-UTRA system performance results show a 2 to 3x improvement over a reference Rel-6 UMTS system configuration [1, 2] for both uplink and downlink.

Transmission technique selector for radio communication systems with multiple transmit and multiple receive antennas

Abstract: A radio communications device ( 102 ) that has multiple receive antennas processes received data communications signals to select between space time coding and spatial multiplexing as a selected transmission technique from a base device ( 104 ) that has multiple transmit antennas. A channel throughput ( 402 - 412, 450 - 454 ) for each transmission technique is estimated based on signal to interference and noise ratios ( 502 - 512, 550 - 554 ) of signals being transmitted through a MIMO channel ( 140 ) as measured by a receiver ( 708 ). The transmission technique with the higher estimated throughput is determined. If spatial multiplexing is determined to have the higher estimated throughput and the throughput of each layer of the spatially multiplexed signal is greater than a threshold, spatial multiplexing is selected. Otherwise, space time coding is selected.

LTE-advanced: next-generation wireless broadband technology [Invited Paper]

Abstract: LTE Release 8 is one of the primary broadband technologies based on OFDM, which is currently being commercialized. LTE Release 8, which is mainly deployed in a macro/microcell layout, provides improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operation and seamless integration with existing systems. LTE-Advanced (also known as LTE Release 10) significantly enhances the existing LTE Release 8 and supports much higher peak rates, higher throughput and coverage, and lower latencies, resulting in a better user experience. Additionally, LTE Release 10 will support heterogeneous deployments where low-power nodes comprising picocells, femtocells, relays, remote radio heads, and so on are placed in a macrocell layout. The LTE-Advanced features enable one to meet or exceed IMT-Advanced requirements. It may also be noted that LTE Release 9 provides some minor enhancement to LTE Release 8 with respect to the air interface, and includes features like dual-layer beamforming and time-difference- of-arrival-based location techniques. In this article an overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed. This includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, uplink spatial multiplexing including extension to four-layer MIMO, and heterogeneous networks with emphasis on Type 1 and Type 2 relays. Finally, the performance of LTEAdvanced using IMT-A scenarios is presented and compared against IMT-A targets for full buffer and bursty traffic model.

Radio transmission device and radio transmission method

Abstract: Provided are a radio transmission device and a radio transmission method capable of improving downlink and uplink throughput even when performing dynamic symbol allocation. In the device and the method, BS and MS share a table correlating a basic TF as a combination of parameters such as TB size used for transmitting only user data, an allocation RB quantity, a modulation method, and an encoding ratio, with a derived TF having user data of different TB size by combining L1/L2 control information. Even when multiplexing L1/L2 control information, Index corresponding to the basic TF is reported from BS to MS.

Intelligent backhaul radio and antenna system

Abstract: A intelligent backhaul radio have an advanced antenna system for use in PTP or PMP topologies. The antenna system provides a significant diversity benefit. Antenna configurations are disclosed that provide for increased transmitter to receiver isolation, adaptive polarization and MIMO transmission equalization. Adaptive optimization of transmission parameters based upon side information provided in the form of metric feedback from a far end receiver utilizing the antenna system is also disclosed.

Base station, communication terminal, transmission method, and reception method

Abstract: A base station includes: means configured to manage frequency blocks; means configured to determine, for each frequency block, scheduling information for assigning one or more resource blocks to a communication terminal being in a good channel state; means configured to generate a control channel including the scheduling information for each frequency block; and means configured to frequency multiplexing control channels within the system frequency band and to transmit it. In addition, the base station transmits the control channel by separating a non-specific control channel to be decoded by a non-specific communication terminal and a specific control channel to be decoded by a communication terminal to which one or more resource blocks are assigned.

Carrier Aggregation in LTE-Advanced

Abstract: UMTS LTE system can support flexible bandwidth configuration up to 20 MHz. Currently, system enhancements are being considered to provide substantial improvements to LTE and allow it to meet or exceed IMT-Advanced requirements. One key enhancement feature is bandwidth extension via carrier aggregation to support deployment bandwidth up to 100 MHz. This will allow peak target data rates in excess of 1 Gbps in the downlink and 500 Mbps in the uplink to be achieved. Carrier aggregation is attractive because it allows operators to deploy a system with larger bandwidth by aggregating several smaller contiguous or non-contiguous carriers while providing backward compatibility to legacy users. For instance, an 80MHz system can be constructed using contiguous or non-contiguous 4×20MHz component carriers. Legacy users can then access the system using one of the component carriers. This paper provides an overview of carrier aggregation and discusses major technical issues including aggregation structure, scenarios, implementation, control signalling design and coexistence with legacy LTE systems.