Traffic Adaptation Research Articles

Dynamic TDD Systems for 5G and Beyond: A Survey of Cross-Link Interference Mitigation

Dynamic time division duplex (D-TDD) dynamically allocates the transmission directions for traffic adaptation in each cell. D-TDD systems are receiving a lot of attention because they can reduce latency and increase spectrum utilization via flexible and dynamic duplex operation in 5G New Radio (NR). However, the advantages of the D-TDD system are difficult to fully utilize due to the cross-link interference (CLI) arising from the use of different transmission directions between adjacent cells. This paper is a survey of the research from academia and the standardization efforts being undertaken to solve this CLI problem and make the D-TDD system a reality. Specifically, we categorize and present the approaches to mitigating CLI according to operational principles. Furthermore, we present the signaling necessary to apply the CLI mitigation schemes. We also present information-theoretic performance analysis of D-TDD systems in various environments. As topics for future works, we discuss the research challenges and opportunities associated with the CLI mitigation schemes and signaling design in a variety of environments. This survey is recommended for those who are in the initial stage of studying D-TDD systems and those who wish to develop a more feasible D-TDD system as a baseline for reviewing the research flow and standardization trends surrounding D-TDD systems and to identify areas of focus for future works.

Emergency traffic adaptive MAC protocol for wireless body area networks based on prioritization.

This paper proposes an emergency Traffic Adaptive MAC (eTA-MAC) protocol for WBANs based on Prioritization. The main advantage of the protocol is to provide traffic ranking through a Traffic Class Prioritization-based slotted-Carrier Sense Multiple Access/Collision Avoidance (TCP-CSMA/CA) scheme. The emergency traffic is handled through Emergency Traffic Class Provisioning-based slotted-CSMA/CA (ETCP-CSMA/CA) scheme. The emergency-based traffic adaptivity is provided through Emergency-based Traffic Adaptive slotted-CSMA/CA (ETA-CSMA/CA) scheme. The TCP-CSMA/CA scheme assigns a distinct, minimized and prioritized backoff period range to each traffic class in every backoff during channel access in Contention Access Period (CAP). The ETCP-CSMA/CA scheme delivers the sporadic emergency traffic that occurs at a single or multiple BMSN(s) instantaneously, with minimum delay and packet loss. It does this while being aware of normal traffic in the CAP. Then, the ETA-CSMA/CA scheme creates a balance between throughput and energy in the sporadic emergency situation with energy preservation of normal traffic BMSNs. The proposed protocol is evaluated using NS-2 simulator. The results indicate that the proposed protocol is better than the existing Medium Access Control (MAC) protocols by 86% decrease in packet delivery delay, 61% increase in throughput, and a 76% decrease in energy consumption.

Activity of a ubiquitin ligase adaptor is regulated by disordered insertions in its arrestin domain.

The protein composition of the plasma membrane is rapidly remodeled in response to changes in nutrient availability or cellular stress. This occurs, in part, through the selective ubiquitylation and endocytosis of plasma membrane proteins, which in the yeast Saccharomyces cerevisiae is mediated by the HECT E3 ubiquitin ligase Rsp5 and arrestin-­related trafficking (ART) adaptors. Here, we provide evidence that the ART protein family members are composed of an arrestin fold with interspersed disordered loops. Using Art1 as a model, we show that these loop and tail regions, while not strictly required for function, regulate its activity through two separate mechanisms. Disruption of one loop mediates Art1 substrate specificity. Other loops are subjected to phosphorylation in a manner dependent on the Pho85 cyclins Clg1 and Pho80. Phosphorylation of the loops controls Art1’s localization to the plasma membrane, which promotes cargo ubiquitylation and endocytosis, demonstrating a mechanism through which Art1 activity is regulated.

AAGAB Controls AP2 Adaptor Assembly in Clathrin-Mediated Endocytosis

Multimeric adaptors are broadly involved in vesicle-mediated membrane trafficking. AP2 adaptor, in particular, plays a central role in clathrin-mediated endocytosis (CME) by recruiting cargo and clathrin to endocytic sites. It is generally thought that trafficking adaptors such as AP2 adaptor assemble spontaneously. In this work, however, we discovered that AP2 adaptor assembly is an ordered process controlled by alpha and gamma adaptin binding protein (AAGAB), an uncharacterized factor identified in our genome-wide genetic screen of CME. AAGAB guides the sequential association of AP2 subunits and stabilizes assembly intermediates. Without the assistance of AAGAB, AP2 subunits fail to form the adaptor complex, leading to their degradation. The function of AAGAB is abrogated by a mutation that causes punctate palmoplantar keratoderma type 1 (PPKP1), a human skin disease. Since other multimeric trafficking adaptors operate in an analogous manner to AP2 adaptor, their assembly likely involves a similar regulatory mechanism.

QoS-Guaranteed Adaptive Bandwidth Allocation for Mobile Multiuser Scalable Video Streaming

Bandwidth allocation plays an important role to guarantee the quality of service (QoS) in streaming real-time scalable video to multiuser over wireless time-varying channels. In this letter, an adaptive bandwidth allocation (ABA) scheme is presented to maximize the bandwidth utilization while provisioning each individual user’s QoS. Cooperated with traffic rate adaptation, it jointly addresses the spatial diversity among multiuser and the temporal fluctuation of the individual channel condition. A continuous-time Markov decision processes model is introduced to formulate the QoS-guaranteed ABA problem as constrained stochastic optimization. Based on performance sensitivity analysis, a policy iteration algorithm is developed to find the optimal ABA policy online without any prior knowledge of channel statistics. The adaptability to unknown environments and high computation efficiency make it feasible to implement in running-time. Simulations results demonstrate the effectiveness of the proposed method.

AMPK-Mediated Regulation of Alpha-Arrestins and Protein Trafficking.

The adenosine monophosphate-activated protein kinase (AMPK) plays a central role in the regulation of cellular metabolism. Recent studies reveal a novel role for AMPK in the regulation of glucose and other carbohydrates flux by controlling the endocytosis of transporters. The first step in glucose metabolism is glucose uptake, a process mediated by members of the GLUT/SLC2A (glucose transporters) or HXT (hexose transporters) family of twelve-transmembrane domain glucose transporters in mammals and yeast, respectively. These proteins are conserved from yeast to humans, and multiple transporters—each with distinct kinetic properties—compete for plasma membrane occupancy in order to enhance or limit the rate of glucose uptake. During growth in the presence of alternative carbon sources, glucose transporters are removed and replaced with the appropriate transporter to help support growth in response to this environment. New insights into the regulated protein trafficking of these transporters reveal the requirement for specific α-arrestins, a little-studied class of protein trafficking adaptor. A defining feature of the α-arrestins is that each contains PY-motifs, which can bind to the ubiquitin ligases from the NEDD4/Rsp5 (Neural precursor cell Expressed, Developmentally Down-regulated 4 and Reverses Spt- Phenotype 5, respectively) family. Specific association of α-arrestins with glucose and carbohydrate transporters is thought to bring the ubiquitin ligase in close proximity to its membrane substrate, and thereby allows the membrane cargo to become ubiquitinated. This ubiquitination in turn serves as a mark to stimulate endocytosis. Recent results show that AMPK phosphorylation of the α-arrestins impacts their abundance and/or ability to stimulate carbohydrate transporter endocytosis. Indeed, AMPK or glucose limitation also controls α-arrestin gene expression, adding an additional layer of complexity to this regulation. Here, we review the recent studies that have expanded the role of AMPK in cellular metabolism to include regulation of α-arrestin-mediated trafficking of transporters and show that this mechanism of regulation is conserved over the ~150 million years of evolution that separate yeast from man.

Efficient Topology Reconstruction via Machine Learning Based Traffic Patterns Recognition in Optically Interconnected Computing System

The traffic flows in parallel computing systems show clustered, correlative nature and the flows are always latency-sensitive. These flows have been abstracted as “Coflow” to pursue overall optimization. Concurrent Coflows on the network show very novel traffic patterns. On the other hand, multiple optical interconnection network architectures have been proposed to enable the traffic adaption topology reconstructions. Nevertheless, topology reconstruction strategies are application-agnostic, and their optimization objective of network performance cannot meet the Coflow demand. In order to exert the flexibility of optical topology to promote the performance of parallel computing application by Coflow acceleration, the traffic patterns are preferred to be well recognized and then an adaptive topology is generated accordingly. To avoid further complex, such recognition is expected to finish without prior knowledge from the application layer. Then, the topology should be reconstructed to minimize the Coflow completion time. To implement these procedures, we proposed a traffic pattern-aware topology reconstruction strategy. Our strategy first combines CNN and spectral clustering to realize the traffic patterns awareness. And then, the genetic searching algorithm is used to mind the proper topology. Based on real traffic trace from Facebook computing application, large-scale simulations have verified the efficiency of such a strategy by lowering the completion time of computing jobs. In addition, the experimental demonstration has confirmed the conclusions.

Biomechanical Control of Lysosomal Secretion Via the VAMP7 Hub: A Tug-of-War between VARP and LRRK1

SummaryThe rigidity of the cell environment can vary tremendously between tissues and in pathological conditions. How this property may affect intracellular membrane dynamics is still largely unknown. Here, using atomic force microscopy, we show that cells deficient in the secretory lysosome v-SNARE VAMP7 are impaired in adaptation to substrate rigidity. Conversely, VAMP7-mediated secretion is stimulated by more rigid substrate and this regulation depends on the Longin domain of VAMP7. We further find that the Longin domain binds the kinase and retrograde trafficking adaptor LRRK1 and that LRRK1 negatively regulates VAMP7-mediated exocytosis. Conversely, VARP, a VAMP7- and kinesin 1-interacting protein, further controls the availability for secretion of peripheral VAMP7 vesicles and response of cells to mechanical constraints. LRRK1 and VARP interact with VAMP7 in a competitive manner. We propose a mechanism whereby biomechanical constraints regulate VAMP7-dependent lysosomal secretion via LRRK1 and VARP tug-of-war control of the peripheral pool of secretory lysosomes.

An optimal cluster formation based energy efficient dynamic scheduling hybrid MAC protocol for heavy traffic load in wireless sensor networks

This article proposes an Energy Efficient Dynamic Scheduling Hybrid MAC Protocol (EDS-MAC) for Traffic Adaptive Wireless Sensor Networks. The proposed approach consists of two stages. (i) cluster formation, and (ii) data transmission. In the first stage, a variable step size firefly algorithm (VSSFFA) is proposed for generating energy-aware clusters by optimal selection of cluster heads. The VSSFFA reduces the cost of locating optimal position for the head nodes in a cluster. Additionally, we proposed the VSSFFA-based approach within the cluster rather than base station, which makes it a semi-distributed method. The selection criteria of the objective function are based on the residual energy, intra-cluster distance, node degree and head count of the probable cluster heads. Data communication is done using data transmission stage, which reduces the latency, delay, and control overhead. Compared to IH-MAC, EDS-MAC reduces the size of control packet by introducing short node address (1 byte instead of 8 bytes in IH-MAC). By enabling lower duty cycle operation and by performing efficient clustering, it reduces overhearing and reduces the overall latency experienced by the sensor network. Hence, introduction of EDS-MAC protocol in WSN can help the users with prolonged network life span and minimize the energy and overhead utilization of the overall network. The efficiency of the proposed MAC protocol has been analyzed using the NS-2 simulator. WSN employing EDS-MAC is compared with IH-MAC and is found to experience 50% reduction in overall energy consumption and 72% reduction in overall delay experienced by the network.

HIV-1 Envelope Glycoprotein Trafficking through the Endosomal Recycling Compartment Is Required for Particle Incorporation.

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) encodes specific trafficking signals within its long cytoplasmic tail (CT) that regulate incorporation into HIV-1 particles. Rab11-family interacting protein 1C (FIP1C) and Rab14 are host trafficking factors required for Env particle incorporation, suggesting that Env undergoes sorting from the endosomal recycling compartment (ERC) to the site of particle assembly on the plasma membrane. We disrupted outward sorting from the ERC by expressing a C-terminal fragment of FIP1C (FIP1C560-649) and examined the consequences on Env trafficking and incorporation into particles. FIP1C560-649 reduced cell surface levels of Env and prevented its incorporation into HIV-1 particles. Remarkably, Env was trapped in an exaggerated perinuclear ERC in a CT-dependent manner. Mutation of either the Yxxϕ endocytic motif or the YW795 motif in the CT prevented Env trapping in the ERC and restored incorporation into particles. In contrast, simian immunodeficiency virus SIVmac239 Env was not retained in the ERC, while substitution of the HIV-1 CT for the SIV CT resulted in SIV Env retention in this compartment. These results provide the first direct evidence that Env traffics through the ERC and support a model whereby HIV-1 Env is specifically targeted to the ERC prior to FIP1C- and CT-dependent outward sorting to the particle assembly site on the plasma membrane.IMPORTANCE The HIV envelope protein is an essential component of the viral particle. While many aspects of envelope protein structure and function have been established, the pathway it follows in the cell prior to reaching the site of particle assembly is not well understood. The envelope protein has a very long cytoplasmic tail that interacts with the host cell trafficking machinery. Here, we utilized a truncated form of the trafficking adaptor FIP1C protein to arrest the intracellular transport of the envelope protein, demonstrating that it becomes trapped inside the cell within the endosomal recycling compartment. Intracellular trapping resulted in a loss of envelope protein on released particles and a corresponding loss of infectivity. Mutations of specific trafficking motifs in the envelope protein tail prevented its trapping in the recycling compartment. These results establish that trafficking to the endosomal recycling compartment is an essential step in HIV envelope protein particle incorporation.

Sorting of a multi-subunit ubiquitin ligase complex in the endolysosome system.

The yeast Dsc E3 ligase complex has long been recognized as a Golgi-specific protein ubquitination system. It shares a striking sequence similarity to the Hrd1 complex that plays critical roles in the ER-associated degradation pathway. Using biochemical purification and mass spectrometry, we identified two novel Dsc subunits, which we named as Gld1 and Vld1. Surprisingly, Gld1 and Vld1 do not coexist in the same complex. Instead, they compete with each other to form two functionally independent Dsc subcomplexes. The Vld1 subcomplex takes the AP3 pathway to reach the vacuole membrane, whereas the Gld1 subcomplex travels through the VPS pathway and is cycled between Golgi and endosomes by the retromer. Thus, instead of being Golgi-specific, the Dsc complex can regulate protein levels at three distinct organelles, namely Golgi, endosome, and vacuole. Our study provides a novel model of achieving multi-tasking for transmembrane ubiquitin ligases with interchangeable trafficking adaptors.

Biomechanical Control of Lysosomal Secretion Via the VAMP7 Hub: A Tug-of-War Mechanism Between VARP and LRRK1

The rigidity of the cell environment can vary tremendously between tissues and in pathological conditions. How this property may affect intracellular membrane dynamics is still largely unknown. Here, using atomic force microscopy, we found that cells deficient in the secretory lysosome v-SNARE VAMP7 were impaired in adapting to substrate rigidity. Conversely VAMP7-mediated secretion was stimulated by more rigid substrate and this regulation depended on the Longin domain of VAMP7. We further found that the Longin domain bound the kinase and retrograde trafficking adaptor LRRK1 and LRRK1 negatively regulated VAMP7-mediated exocytosis. Conversely, VARP, a VAMP7- and kinesin 1- interacting protein, further controlled the availability for secretion of peripheral VAMP7 vesicles and response of cells to mechanical constraints. We propose a mechanism whereby biomechanical constraints regulate VAMP7-dependent lysosomal secretion via LRRK1 and VARP tug-of-war control of the peripheral readily-releasable pool of secretory lysosomes.

Multilevel regulation of an α-arrestin by glucose depletion controls hexose transporter endocytosis.

Nutrient availability controls the landscape of nutrient transporters present at the plasma membrane, notably by regulating their ubiquitylation and subsequent endocytosis. In yeast, this involves the Nedd4 ubiquitin ligase Rsp5 and arrestin-related trafficking adaptors (ARTs). ARTs are targeted by signaling pathways and warrant that cargo ubiquitylation and endocytosis appropriately respond to nutritional inputs. Here, we show that glucose deprivation regulates the ART protein Csr2/Art8 at multiple levels to trigger high-affinity glucose transporter endocytosis. Csr2 is transcriptionally induced in these conditions through the AMPK orthologue Snf1 and downstream transcriptional repressors. Upon synthesis, Csr2 becomes activated by ubiquitylation. In contrast, glucose replenishment induces CSR2 transcriptional shutdown and switches Csr2 to an inactive, deubiquitylated form. This glucose-induced deubiquitylation of Csr2 correlates with its phospho-dependent association with 14-3-3 proteins and involves protein kinase A. Thus, two glucose signaling pathways converge onto Csr2 to regulate hexose transporter endocytosis by glucose availability. These data illustrate novel mechanisms by which nutrients modulate ART activity and endocytosis.

Analysis of YouTube’s traffic adaptation to dynamic environments

The popular Internet service, YouTube, has adopted by default the HyperText Markup Language version 5 (HTML5). With this adoption, YouTube has moved to Dynamic Adaptive Streaming over HTTP (DASH) as Adaptive BitRate (ABR) video streaming technology. Furthermore, rate adaptation in DASH is solely receiver-driven. This issue motivates this work to make a deep analysis of YouTube’s particular DASH implementation. Firstly, this article provides a state of the art about DASH and adaptive streaming technology, and also YouTube traffic characterization related work. Secondly, this paper describes a new methodology and test-bed for YouTube’s DASH implementation traffic characterization and performance measurement. This methodology and test-bed do not make use of proxies and, moreover, they are able to cope with YouTube traffic redirections. Finally, a set of experimental results are provided, involving a dataset of 310 YouTube’s videos. The depicted results show a YouTube’s traffic pattern characterization and a discussion about allowed download bandwidth, YouTube’s consumed bitrate and quality of the video. Moreover, the obtained results are cross-validated with the analysis of HTTP requests performed by YouTube’s video player. The outcomes of this article are applicable in the field of Quality of Service (QoS) and Quality of Experience (QoE) management. This is valuable information for Internet Service Providers (ISPs), because QoS management based on assured download bandwidth can be used in order to provide a target end-user’s QoE when YouTube service is being consumed.

Deubiquitinating enzymes Ubp2 and Ubp15 regulate endocytosis by limiting ubiquitination and degradation of ARTs.

Endocytic down-regulation of cell-surface proteins is a fundamental cellular process for cell survival and adaptation to environmental stimuli. Ubiquitination of cargo proteins serves as the sorting signal for downstream trafficking and relies on the arrestin-related trafficking adaptor (ART)-Rsp5 ubiquitin ligase adaptor network in yeast. Hence proper regulation of the abundance and activity of these ligase-adaptor complexes is critical for main-tenance of optimal plasma membrane protein composition. Here we report that the stability of ARTs is regulated by the deubiquitinating enzymes (DUBs) Ubp2 and Ubp15. By counteracting the E3 ubiquitin ligase Rsp5, Ubp2 and Ubp15 prevent hyperubiquitination and proteasomal degradation of ARTs. Specifically, we show that loss of both Ubp2 and Ubp15 results in a defect in Hxt6 endocytosis associated with Art4 instability. Our results uncover a novel function for DUBs in the endocytic pathway by which Ubp2 and Ubp15 positively regulate the ART-Rsp5 network.

Traffic Adaptive MAC Protocols in Wireless Body Area Networks

In Wireless Body Area Networks (WBANs), every healthcare application that is based on physical sensors is responsible for monitoring the vital signs data of patient. WBANs applications consist of heterogeneous and dynamic traffic loads. Routine patient’s observation is described as low-load traffic while an alarming situation that is unpredictable by nature is referred to as high-load traffic. This paper offers a thematic review of traffic adaptive Medium Access Control (MAC) protocols in WBANs. First, we have categorized them based on their goals, methods, and metrics of evaluation. The Zigbee standard IEEE 802.15.4 and the baseline MAC IEEE 802.15.6 are also reviewed in terms of traffic adaptive approaches. Furthermore, a comparative analysis of the protocols is made and their performances are analyzed in terms of delay, packet delivery ratio (PDR), and energy consumption. The literature shows that no review work has been done on traffic adaptive MAC protocols in WBANs. This review work, therefore, could add enhancement to traffic adaptive MAC protocols and will stimulate a better way of solving the traffic adaptivity problem.

Traffic Adaptive Synchronized Cluster Based MAC Protocol for Cognitive Radio Ad Hoc Network

In wireless communication, Cognitive Radio Network (CRN) is the contemporary research area to improve efficiency and spectrum utilization. It is structured with both licensed users and unlicensed users. In CRN, unlicensed users also called Cognitive Radio (CR) users are permitted to utilize the free/idle of licensed channels without harmful interference to licensed users. However, accessing idle channels is the big challenging issue due to licensed users’ activities. A large number of cluster based MAC protocol have been proposed to solve this issue. In this paper, we have come up with a Traffic Adaptive Synchronized Cluster Based MAC Protocol for Cognitive Radio Ad Hoc Network, with the target of creating cluster structure more vigorous to the licensed users’ channel re-occupancy actions, maximize throughput, and minimize switching delay, so that CR users be able to use the idle spectrum more efficiently. In our protocol, clusters are formed according to Cluster Identification Channel (CIC) and inter-communication is completed without gateway nodes. Finally, we have analysed and implemented our protocol through simulation and it provides better performance in terms of different performance metrics.

Traffic Adaptation and Energy Efficiency for Small Cell Networks With Dynamic TDD

The traffic in current wireless networks exhibits large variations in uplink (UL) and downlink (DL), which brings huge challenges to network operators in efficiently allocating radio resources. Dynamic time-division duplex (TDD) is considered a promising scheme that is able to adjust the resource allocation to the instantaneous UL and DL traffic conditions, also known as traffic adaptation. In this paper, we study how traffic adaptation and energy harvesting can improve the energy efficiency (EE) in multi-antenna small cell networks operating dynamic TDD. Given the queue length distribution of small cell access points (SAPs) and mobile users (MUs), we derive the optimal UL/DL configuration to minimize the service time of a typical small cell, and show that the UL/DL configuration that minimizes the service time also results in an optimal network EE, but does not necessarily achieve the optimal EE for SAP or MU individually. To further enhance the network EE, we provide SAPs with energy harvesting capabilities, and model the status of harvested energy at each SAP using a Markov chain. We derive the availability of the rechargeable battery under several battery utilization strategies, and observe that energy harvesting can significantly improve the network EE in the low traffic load regime. In summary, the proposed analytical framework allows us to elucidate the relationship between traffic adaptation and network EE in future dense networks with dynamic TDD. With this work, we quantify the potential benefits of traffic adaptation and energy harvesting in terms of service time and EE.

Identification of the endocytic sorting signal recognized by the Art1-Rsp5 ubiquitin ligase complex.

Targeted endocytosis of plasma membrane (PM) proteins allows cells to adjust their complement of membrane proteins to changing extracellular conditions. For a wide variety of PM proteins, initiation of endocytosis is triggered by ubiquitination. In yeast, arrestin-related trafficking adaptors (ARTs) enable a single ubiquitin ligase, Rsp5, to specifically and selectively target a wide range of PM proteins for ubiquitination and endocytosis. However, the mechanisms that allow ARTs to specifically recognize their appropriate substrates are unknown. We present the molecular features in the methionine permease Mup1 that are required for Art1-Rsp5-mediated ubiquitination and endocytosis. A combination of genetics, fluorescence microscopy, and biochemistry reveals three critical features that comprise an ART sorting signal in the Mup1 N-terminal cytosolic tail: 1) an extended acidic patch, 2) in close proximity to the first Mup1 transmembrane domain, and 3) close to the ubiquitinated lysines. We show that a functionally similar ART sorting signal is also required for the endocytosis of a second Art1-dependent cargo, Can1, suggesting a common mechanism for recognition of Art1 substrates. We isolate two separate suppressor mutations in the Art1 C-terminal domain that allele-specifically restore endocytosis of two Mup1 acidic patch mutants, consistent with an interaction between the Art1 C-terminus and the Mup1 acidic patch. We propose that this interaction is required for recruitment of the Art1-Rsp5 ubiquitination complex.

Dynamic Uplink - Downlink Configuration in TD-LTE with HARQ Feedback

Mobile communication has become data centric and data traffic is increasing exponentially. LTE systems were originally designed for symmetric & almost fixed uplink and downlink capacity distribution. The pattern of data usage is dynamic and incommensurable for uplink and downlink. Enhanced Interference Mitigation and Traffic Adaptation (eIMTA) is one of the features which enable TD-LTE systems to handle asymmetric and dynamic uplink and downlink capacity requirements. eIMTA allows dynamic changes to configurable TDD patterns for uplink and downlink. There are impacts on HARQ timeline, acknowledgement transmission timing because of changes in uplink & downlink configuration. This paper explains eIMTA and HARQ timeline issues and proposes semi-static HARQ timeline mechanism. SIB1 indicated uplink HARQ reference configuration for each serving cell solves uplink sub-frame mismatch issue. Device can derive reference configuration for each cell's uplink and downlink HARQ on basis of HARQ timeline. Downlink HARQ based soft buffer partitioning has semi-static changes, which helps to minimize throughput loss.