With the pervasiveness of wireless devices, machine-to-machine (M2M) communications or machine-type-communications (MTC) is emerging to support data transfer among devices without human interaction. In this paper, we introduce a tractable queueing model for performance modeling and analysis for heterogeneous MTC. We then demonstrate versatile applications of the proposed queueing model. Firstly, we use the queueing model to study the coexistence between M2M communications of MTC devices and human-to-human (H2H) communications in the same networks. We also consider more sophisticated settings, where the MTC user equipments (UEs) are able to perform the transmission to the macro Evolved Node B (eNodeB) or small-cell eNodeB, or perform the relay transmission. In addition, we extend our study to analyze the eNodeB selection and coalition formation for relay transmission when MTC UEs coexist with H2H UEs. In this case, we formulate the non-transferable utility (NTU) coalitional game to model the eNodeB selection and coalition formation for relay transmission. The performance evaluation reveals some interesting results. For example, the throughput of MTC UEs can be improved when the MTC UEs spend more time inactive due to lower contention in the network, compared with the case when the MTC UEs are mostly active.

Performance Modeling and Analysis of Heterogeneous Machine Type Communications

Rapid growth of machine-to-machine (M2M) communications necessitates the reevaluation of the Long Term Evolution-Advanced (LTE-A) performance, since the current standard is not optimized for intensive M2M traffic. A serious issue is that massive M2M arrivals can overload the LTE-A random access channel, resulting in a significant access delay. There have been a number of proposals to control this overload; however, there are no studies on the mathematical characterization of delay bounds to the best of our knowledge. Here, we derive lower bounds for the LTE-A average random access delay for both a regular traffic pattern (uniformly distributed arrivals) and for a traffic pattern, indicating a serious congestion (beta-distributed arrivals). The proposed delay bounds, which predict the minimum delay with less than 6% error, present the fundamental limits of delay that can be achieved by a practical load-balancing algorithm. This paper is also one of the first attempts toward the mathematical analysis of beta-distributed arrivals. We also analyze the effect of estimation accuracy, frequency of random access opportunities, and the number of preambles on the access delay. We show that it is possible to reduce the access delay by several orders of magnitude using an appropriate configuration of these system parameters.

Lower Bounds on the LTE-A Average Random Access Delay Under Massive M2M Arrivals

LTE-Advanced networks employ random access based on preambles transmitted according to multi-channel slotted Aloha principles. The random access is controlled through a limit $W$ on the number of transmission attempts and a timeout period for uniform backoff after a collision. We model the LTE-Advanced random access system by formulating the equilibrium condition for the ratio of the number of requests successful within the permitted number of transmission attempts to those successful in one attempt. We prove that for $W \leq 8$ there is only one equilibrium operating point and for $W \geq 9$ there are three operating points if the request load $\rho$ is between load boundaries $\rho_{1}$ and $\rho_{2} $ . We analytically identify these load boundaries as well as the corresponding system operating points. We analyze the throughput and delay of successful requests at the operating points and validate the analytical results through simulations.

Impact of Retransmission Limit on Preamble Contention in LTE-Advanced Network

A base station employs control signaling for contention-based uplink access from user equipment devices to the base station. Contention-based access configuration is performed via physical downlink control channel signaling. Configuration data sent to the user equipment devices identifies (502) multiple contention-based access zones, along with minimum power headroom values (506) for each contention-based access zone. A probability factor (508) may be used to lower collision possibility by influencing whether the user equipment devices perform contention-based uplink access.

Method and apparatus for providing contention-based resource zones in a wireless network

A scheduling request method, network side device, terminal device and system, belong to the field of communications technologies. The method includes: configuring a first shared resource used for a scheduling request (SR), and sending first information to multiple terminal devices to notify of the first shared resource ( 101 ); receiving the SR on the first shared resource ( 102 ); allocating a second shared resource of uplink data to the multiple terminal devices, or allocating a dedicated resource of uplink data to at least one of the multiple terminal devices ( 103 ). The network side device includes: a configuration module, a receiving module and an allocation module. The terminal device includes: a receiving module, a request module and a sending module. The present invention avoids the waste of the uplink data resource, and improves a utilization rate of the uplink data resource and a transmission success rate of the uplink data.

Scheduling request method, apparatus and system

A wireless communication system as described here employs control signaling for contention-based uplink access from user equipment devices to a base station. Contention-based access configuration is performed via physical downlink control channel signaling. Configuration data sent to the user equipment devices identifies multiple contention-based access zones, along with minimum power headroom values for each contention-based access zone. A probability factor may also be used to lower collision possibility by influencing whether the user equipment devices perform contention-based uplink access. An uplink grant message can be used to acknowledge contention-based transmission; contention resolution is achieved implicitly via the uplink grant.

Method and apparatus for determining when to use contention-based access for transmitting data in a wireless network

TDD version of 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) provides a mode of operation in a single block of spectrum with Uplink and Downlink 1ms-subframes multiplexed in time. Limited number of Uplink subframes coupled with unequal number of Physical Random Access Channel (RACH) opportunities per subframe results in TDD LTE RACH resources and the offered load being non-uniform in time. Thus, performance of TDD LTE RACH is different from classical multi-channel slotted ALOHA analyzed in the past. We derive the offered load in each subframe assuming the details of TDD LTE configuration and subsequently compute the normalized throughput under Poisson load. We show that non-uniform RACH resource allocation across subframes does not cause throughput degradation as long as the resources are located in the same half of the 10ms-radio frame. For selected “worst-case” 3GPP configurations we show that the degradation is less than 10%. Our results provide capacity estimates for the RACH in TDD LTE which can be used for sizing under different traffic conditions.

Throughput analysis of TDD LTE Random Access Channel

An exemplary embodiment in accordance with this invention provides a method of managing a set of uplink reception paths and controlling the timing of uplink transmission of a UE. The method includes selecting a dominant path from a plurality of paths based at least in part on measurements of the plurality of paths. A path describes a communication route from a mobile device to an access point via a RRH. The method also includes selecting a plurality of non-dominant serving paths from the plurality of paths based at least in part on the measurements; determining a timing window based at least in part on the dominant path; determining a TA for the mobile device based at least in part on the timing window and sending the TA to the mobile device. Apparatus and computer readable media are also described.

Switching between remote radio heads

A method for performing time advance (TA) management is described. An assignment of a first TA group is transmitted to a mobile device. The mobile device measures a strength of a signal from a first access point (AP). The mobile device determines whether to send a random access preamble based at least in part on the strength of the signal from the first AP and a strength of a signal from a second AP. A current downlink (DL) path includes the second AP. The method includes, in response to determining to send a random access preamble, transmitting the random access preamble, the random access preamble is received from the mobile device. In response to the random access preamble, the method includes determining a second TA group for the mobile device. The method also includes transmitting an assignment of the second TA group. Apparatus and computer readable media are also described.

Timing advance management in the presence of repeaters and remote radio heads

The invention discloses a user equipment device operating in a wireless communication system and an operating method thereof. The user equipment device operating in a wireless communication system andan operating method thereof are disclosed. An apparatus and method employs control signaling for contention-based uplink access from a user equipment device to a base station. The amount of data to be transmitted from the user equipment device to the base station is identified. Then, the next scheduled transmission time for dedicated access to the base station is determined. When the amount of time until the next scheduled transmission time for dedicated access to the base station is longer than the threshold time or only one resource allocation is needed to accommodate all the identified amount of data, a contention-based access to the base station is used. A data packet containing the identified amount of data is transmitted. However, when the identified amount of data cannot be transmitted using only one resource allocation, and until the time of the next scheduled transmission time is shorter than the threshold amount of time, dedicated access for scheduling of the base station isused to transmit at least some of the data packets containing the identified amount.

Igor Filipovich

Papers

Method and apparatus for determining when to use contention-based access for transmitting data in a wireless network

Throughput analysis of TDD LTE Random Access Channel

Switching between remote radio heads

Timing advance management in the presence of repeaters and remote radio heads

User equipment device operating in wireless communication system and operating method thereof