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Performance analysis of uplink packet schedulers in cellular networks with relaying
- In IFIP wireless and mobile networking WMNC’09
, 2009
"... Abstract. Deployment of intermediate relay nodes in cellular networks, e.g. UMTS/ HSPA, has been proposed for service enhancement, which is of particular importance for uplink users at the cell edge suffering from low power capacity and relatively poor channel conditions. In this paper, we propose ..."
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Abstract. Deployment of intermediate relay nodes in cellular networks, e.g. UMTS/ HSPA, has been proposed for service enhancement, which is of particular importance for uplink users at the cell edge suffering from low power capacity and relatively poor channel conditions. In this paper, we propose and investigate a number of uplink packet scheduling schemes deploying the relay functionality in different ways. Using a combined packet and flow level analysis capturing the specifics of the scheduling schemes and the random behavior of the users (initiation and completion of flow transfers), the performance of the various schemes is evaluated and compared to a reference scenario where relaying is not used. The main performance measures considered in our study are the instantaneous data rate, the energy consumption and the mean flow transfer time. Interestingly, considering flow transfer times, it is found that the use of relay nodes is not only particularly beneficial for users at the cell edge but also has a strongly positive effect on the performance of users at locations close to the base station.
Performance of relay-enabled uplink in cellular network - a flow level analysis
- ICUMT’09, St
, 2009
"... Abstract—Uplink users in cellular networks, such as UMTS/ HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage and increasing data rates. This paper focuses on the role ..."
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Abstract—Uplink users in cellular networks, such as UMTS/ HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage and increasing data rates. This paper focuses on the role of packet scheduling in cellular networks with relay nodes. In particular, two uplink scheduling schemes deploying the relay functionality in different ways are compared in performance to a reference scenario where relaying is not used. We derive expressions which characterize for each of the two relay-enabled schedulers the service area of a relay station as a function of the relay location and transmit power. The results show that the service area is significantly influenced by the type of scheduling. Examining the impact on the effective data rates of mobile stations shows that there is a combination of the relay’s position and transmit power which optimizes uplink service. Furthermore, based on calculations of flow throughput, we show that relaying improves flow level performance of all users, including those who do not use the relay. I.
Impact of inter-cell interference on flow level performance of scheduling schemes for yhe umts eul.” WiMob’08
, 2008
"... Abstract—The UMTS Enhanced Uplink (EUL) is expected to provide higher capacity, increased data rates, and smaller latency on the communication link from users towards the network. A key mechanism in EUL traffic handling is the packet scheduler, for which a number of basic schemes can be identified ( ..."
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Abstract—The UMTS Enhanced Uplink (EUL) is expected to provide higher capacity, increased data rates, and smaller latency on the communication link from users towards the network. A key mechanism in EUL traffic handling is the packet scheduler, for which a number of basic schemes can be identified (one-by-one, partial parallel, and full parallel). In this paper we analyze the interaction between the EUL scheduling scheme deployed in the network and the inter-cell interference. On the one hand, dif-ferent scheduling schemes cause different inter-cell interference patterns on neighbouring cells. On the other hand, the different schemes are affected by inter-cell interference in different ways. The scheduling schemes are evaluated and compared under different approaches for reserving part of the allowed noise rise at the base station for inter-cell interference. For our analysis, we have developed a hybrid analytical/simulation approach allowing for fast evaluation of performance measures such as the mean flow transfer time and fairness expressing how the performance depends on the user’s location. This approach takes into account both the packet-level characteristics and the flow-level dynamics due to the random user behaviour.
Flow-level Modeling and Optimization of Intercell Coordination with Dynamic TDD
"... ABSTRACT We study the intercell coordination problem between two interfering cells combined with dynamic time-division duplexing (TDD). In dynamic TDD, each station selects in each time slot whether it is serving uplink (u) or downlink (d) traffic. Thus, the system has four possible operation modes ..."
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ABSTRACT We study the intercell coordination problem between two interfering cells combined with dynamic time-division duplexing (TDD). In dynamic TDD, each station selects in each time slot whether it is serving uplink (u) or downlink (d) traffic. Thus, the system has four possible operation modes (uu, ud, du, dd). The amount of intercell interference between the stations clearly depends on the operation mode. We consider a flow-level model where traffic consists of elastic data flows in both cells (cells 1 and 2) and in both directions (uplink and downlink). We first characterize the maximal stability region, and then determine the optimal static (i.e., state-independent) policy. Our main objective is to analyze the potential gains from applying dynamic (i.e., state-dependent) policies, where the chosen operation mode depends on the instantaneous state of the system. To this end, motivated by certain stochastic optimality results in the literature, we define several priority policies. As a reference policy, we have the well-known max-weight policy, and we also develop another dynamic policy by applying the policy iteration algorithm. Notably we prove that certain simple priority policies are, in fact, stochastically optimal in some special cases, but which policy is optimal depends on the setting. To study the exact performance gains achieved by the dynamic policies, we perform extensive simulations. While our stochastic optimality results require exponential service times, in the simulations, we also study the impact of nonexponential service times and consider a physical model where the service time distribution is determined by the joint distribution of flow sizes and the random location of the corresponding user in the cell area. The max-weight policy is, as expected, performing well but the various priority policies are sometimes better and even optimal. Jointly the results indicate that dynamic policies give significant performance gains compared with the optimal static policy.
Minimizing file transfer delays using SRPT in HSDPA with terminal constraints
"... Abstract—In an HSDPA system, multiple users are scheduled in a time slot due to constraints on the user terminals with respect to how many codes a particular user can utilize. We model the allocation of the codes at the so-called flow level. This results in a particular multiserver queuing model, wh ..."
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Abstract—In an HSDPA system, multiple users are scheduled in a time slot due to constraints on the user terminals with respect to how many codes a particular user can utilize. We model the allocation of the codes at the so-called flow level. This results in a particular multiserver queuing model, where codes correspond to servers and multiple servers are allocated per flow subject to constraints on the maximum number of codes. In this context, we focus on minimizing the mean flow delays by utilizing flow-level information on the remaining service times. While SRPT is the optimal policy for minimizing the mean delay in an M/G/1 queue, no such optimality results exist for the dynamic setting in multiserver models. We derive a heuristic SRPT policy for the system and evaluate its performance against the fair round-robin policy, which can be modeled at the flow-level as a processor sharing system. The results demonstrate that using SRPT-like scheduling can significantly decrease the overall mean delays, as well as the conditional delays. Index Terms—flow-level analysis, multiserver models, sizebased scheduling, SRPT, cellular networks, HSDPA I.
prof. dr. ir. S. M. Heemstra de Groot prof. dr. R. D. van der Mei
, 1981
"... Analysing uplink scheduling in mobile networks ..."
Enhanced Uplink Scheduling for Continuous Connectivity in High Speed Packet Access Systems
, 2011
"... The efficiency of high speed packet access (HSPA) systems is mainly based on channel quality information (CQI) re-ports transmitted by user equipment (UE) to Node B. In this paper, we propose an improved CQI prediction scheme based on a finite state Markov chain (FSMC) model for wireless channel, in ..."
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The efficiency of high speed packet access (HSPA) systems is mainly based on channel quality information (CQI) re-ports transmitted by user equipment (UE) to Node B. In this paper, we propose an improved CQI prediction scheme based on a finite state Markov chain (FSMC) model for wireless channel, in order to reduce CQI signaling overhead in the HSPA system. Then, we introduce an enhanced uplink packet scheduling (EUPS) scheme to provide quality of ser-vices (QoS) guaranteed for continuous packet connectivity in the enhanced uplink (EUL). EUPS serves the active UEs not only according to buffer status but also according to reported state of the wireless channel of each UE. The per-formance of the proposed scheme in terms of average packet delay, average packet drop and average cell throughput is compared to the classical scheduler of 3GPP standards. The simulation results show the effectiveness of the proposed scheme.
