Supporting First Person Shooter Games in Wireless Local Area Networks

Traditional single player first person shooter (FPS) games adopt a generally linear level design. Players are not given much choice as to where to go next, and thus it is paramount that the designer is able to keep the player interested throughout the whole level. It is widely accepted that in order to keep the player's interest, it is important to offer the player a varied gaming experience by presenting high interest and low interest encounters in an alternating fashion. However, while there are general theories and rules of thumb as to how this can be done, there is little formal knowledge about how exactly high or low interest levels can be achieved. Our goal is to create a better understanding on how to design encounters that affect interest levels in linear FPS games. Specifically, how exactly a player's interest levels can be raised intentionally. To accomplish this, we developed a method for measuring and comparing player interest levels based on electroencephalogram (EEG) data measured using a “Neurosky Mindset” unit, which is a commercially available EEG device. We measured player EEG data for the first 4 levels of the FPS game “Call of Duty: Modern Warfare 2” and calculated player interest levels for the entire length of gameplay. By referring to recorded gameplay videos, we were able to associate each increase in interest levels for each player to a specific point in game. From this data, we found and isolated points in each level where most players showed a rise in interest levels, and discovered that certain patterns existed between these situations. These findings led to another study where we further analyzed these situations and found out what factors caused most players to show a rise in interest levels. We were able to divide these factors into 6 different categories called Triggers: “Anticipation”, “Concentration”, “Surprise”, “Frustration”, “Overwhelm” and “Fear”. As these triggers represent mutually exclusive elements that affect a player's interest levels, we found that in most situations where many test subjects showed a rise in interest levels, more than one trigger is present, a phenomenon we call Stacking. While our study is still ongoing, we believe that by using these triggers as guidelines, game designers will be able to intentionally plan and control the player's interest level for FPS games with a certain level of guarantee.

When player skill levels are different in competitive First Person Shooter (FPS) games, the weaker player can end up feeling discouraged and the stronger player may get bored with the lack of challenge — ultimately yielding a non-optimal play experience for both players. Previous work has investigated how aiming assistance can be applied in a 3D environment to assist weaker players; however, there is little information on whether aiming assistance balances gameplay in a multiplayer environment or on how aim assistance affects player experience. We carried out a study to test the effectiveness of two aim assistance techniques (Bullet Magnetism and Area Cursor) that have been shown to help aiming in a 3D FPS. Our study had novice-expert pairs play deathmatch games in a multiplayer 3D FPS with and without the assistance techniques. The study showed that although Area Cursor and Bullet Magnetism resulted in better performance of the weaker player, it did not result in closer scores, and had no effect on the players' enjoyment of the game. Our results indicate that balancing performance in 3D FPS games is more complex than simply helping weaker players' aim, and we suggest possible reasons that warrant further investigation. This study is the first realistic evaluation of balancing techniques for 3D First Person Shooters, providing empirical evidence of the difficulty of using aim assistance techniques for balancing competitive gameplay.

This paper describes the results of a study designed to understand the components contributing to a participant's assessment of threatening situations in a competitive First Person Shooter (FPS) game Quake III: Arena. The analysis process described compares theoretical, questionnaire based data with that of actual game play footage and identifies how skill and experience can affect a player's ability to accurately assess threat. This research also identifies relationships between variables contributing to a participant's threat assessment process which are not usually acknowledged in game AI design. A suggestion for integrating player-like threat based decision making processes is proposed.

Modelling traffic generated by Internet based multiplayer computer games has attracted a great deal of attention in the past few years. In part this has been driven by a need to simulate correctly the network impact of highly interactive online game genres such as the first person shooter (FPS). Time-series models are important elements in the creation of realistic traffic generators for network simulators such as ns-2 and OMNeT++ as they account for the correlation between packets. In this paper we show that the time-series behaviour of FPS server-to-client packet lengths is well modelled by ARMA(1,1) processes. We report on data from six popular FPS games of the past 10 years including Half-Life, Half-Life Counter-Strike, Half-Life 2, Half-Life 2 Counter-Strike, Quake III Arena and Wolfenstein Enemy Territory. For each of these games we analyse sessions each comprising 2 to 9 players. In all cases ARMA(1,1) is an effective model. We also show that AR models of order 1 and higher fail to capture the packet size variance as effectively as ARMA(1,1). Finally we show that higher order ARMA models are no more effective in describing the time-series behaviour than the simpler ARMA(1,1) models.

Wireless Local Area Networks (WLAN)s are today common for access to Internet; well-known and used is IEEE 802.11 standardized technology. Some drawbacks of the standardized distributed medium access scheme, Distributed Coordination Function (DCF) has resulted in considerations made to extend the DCF from single-hop communications to multi-hop. Multihopping has the potential to reduce energy consumption and increase throughput and coverage. The drawback is lack of Quality-of-Service (QoS) support, which already with single-hop communication was bad, but extending a communication between two peers to multi-hop significantly reduces the possibility to offer reliable transmissions. The contention-based medium access performed at each hop with the DCF results in large uncertainties as to when a packet arrives to its end-destination. There are two general approaches for extending the DCF with QoS functionality: 1. Allocate resources for a flow and 2. Assign a flow higher priority than other flows. My hypothesis is that for strict QoS guarantees, a reservation-based approach is the better one. This has been my motivation to design a new medium access protocol; based on the DCF, periodic time slots for QoS-demanding real-time applications are reserved. The Distributed Allocation of time slots for Real-time traffic (DARE) is unique as it totally distributed sets up an end-to-end reservation before the transmission of data begins, repairs broken reservations, support many periods and time slot sizes and distribute piggy-backed information even to a two-hop radius from a receiver. This thesis describes the DARE protocol and also presents results from comparisons of DARE, DCF and the IEEE 802.11 E standardized priority-based QoS medium access protocol Enhanced Distributed Channel Access (EDCA). Using simulations, this thesis shows that DARE offers constant end-to-end packet delay for a flow, very low average packet delay in the whole system and constant throughput. EDCA and DCF depend strongly on the total network load; average packet delay for a real-time flow increases rapidly with the surrounding load. DARE outperforms both DCF and EDCA when many flows are present, even in networks with frequent topology changes where reservations must be repaired. Thus, the reservation-based DARE protocol is the most suitable approach for extending DCF with QoS.

Modelling traffic generated by Internet based multiplayer computer games has attracted a great deal of attention in the past few years. In part this has been driven by a desire to properly simulate the network impact of highly interactive online game genres such as the first person shooter (FPS). Past work has dealt with packet size and packet interarrival times without consideration of packet size autocorrelations. Packet size auto-correlation is an important element in the creation of plausible traffic generators for network simulators such as ns-2 and omnet++. In this paper we present an analysis of the auto-correlation of packet size for Half-Life, Half-Life Counterstrike, Half-Life 2, Half-Life 2 Counterstrike, Quake III Arena and Wolfenstein Enemy Territory. We show that packet sizes appear to be autocorrelated.

Future Quality of Service (QoS) aware networks, such as those based on the Differentiated Services (DiffServ) architecture, will provide users with the opportunity to assign a priority to the traffic they receive and generate. Different priorities will entail different per-byte or per-packet charges. To aid users operating within such an environment, a priority selection strategy is required. In this paper, we propose a priority selection strategy based on the concept of Consumer Surplus (CS), which is the positive difference between utility or the user's willingness-to-pay and cost. We then evaluate this strategy in a networking scenario where a user is involved in a multiplayer Counterstrike game, in which different priorities may be assigned to the downstream traffic. A utility curve, applicable to a First Person Shooter (FPS) game like Counterstrike, is presented. Using simulation results we show that for varied traffic loads, the CS strategy offers comparable application performance to that of always selecting the highest priority, but at a reduced cost to the user.

There has been an explosive growth in the use of wireless LANs (WLANs) to support network applications ranging from web-browsing and file-sharing to voice calls. It is difficult to optimally configure WLAN components, such as access points (APs), to meet the quality-of-service requirements of the different applications, as well as ensuring flow-level fairness. Recent work has shown that the widely-deployed IEEE 802.11 MAC Distributed Coordination Function (DCF) is biased against downstream flows. The new IEEE 802.11e standard introduces QoS mechanisms, such as Enhanced Distributed Channel Access (EDCA), that allow this unfairness to be addressed. So far, only limited work has been done to evaluate the impact of these MAC protocols on TCP-based applications. In this paper, through ns-2 simulations, we evaluate the impact of EDCA on TCP application traffic consisting of both long and short-lived TCP flows. We find that the performance of TCP applications is very dependent upon the settings of the EDCA parameters and buffer lengths at the AP. We also show that the performance of the admission control strategy employed depends on the buffer lengths at the AP and the traffic intensity.

In the emerging standard IEEE 802.11e, the Enhanced Distributed Channel Access (EDCA) is specified to support quality-of-service (QoS) in wireless local area networks (WLAN). This paper aims at providing a thoroughly analytical model that captures the operation of the AIFSs, contention window sizes and retry limits differentiation for different services of the EDCA mechanism under saturation condition based on a three-dimensional Markov Chain model. The analytical model is validated and provides an in-depth understanding and insights into the EDCA protocol, and effectiveness of different parameters on the system performance in terms of system throughput and frame dropping probability for differentiation services traffic is investigated through extensive numerical and simulation results. Moreover, the analytical model can be cooperated into the admission control algorithm with different parameters in terms of AIFS, contention window sizes and retry limits.

Nature and origin of presence are still unclear. Although it can be characterized, under a neurophysiological perspective, as a process resulting from a synchrony between cognitive and perceptive systems, the multitude of associated processes reduces the chances of brain mapping presence. In this way, our study was designed in order to understand the possible role of VR experience on presence in a virtual environment. For our study, 16 participants (M=28.39 years; SD=13.44) of both genders without computer experience were selected. The study design consisted of two assessments (initial and final), where the participants were evaluated with BFI, PQ, ITQ, QC, MCSDS-SF, STAI, visual attention and behavioral measures after playing an first person shooter (FPS) game. In order to manipulate the level of VR experience the participants were trained on, a different FPS was used during the 12 weekly sessions of 30 minutes. Results revealed significant differences between the first and final assessment for presence (F(1,15)=11.583; MSE=775.538; p<01) and immersion scores (F(1,15)=6.234; MSE=204.962; p<05), indicating higher levels of presence and immersion in the final assessment. No statistical significant results were obtained for cybersickness or the behavioral measures. In summary, our results showed that training and the subsequent higher computer experience levels can increase immersion and presence.

With the provisioning of high-speed wireless LAN (WLAN) environments, multi- media services (e.g., VoIP and video-conference) with different QoS requirements will be available in next generation WLANs. Multimedia services could be categorized into multiple traffic classes and different priorities will be applied to access the wireless me- dium. The IEEE 802.11 working group has been developing a new generation distributed access protocol, called enhanced distributed channel access (EDCA), to support service differentiation in the 802.11 MAC layer. Service differentiation is achieved by assigning different values of EDCA access parameters (i.e., minimum contention window, maxi- mum contention window, and arbitration interframe space) to different traffic classes. To investigate the system performance under various network conditions, it is helpful to have a theoretical model for EDCA. In this paper, we introduce an analytical model for EDCA so that the saturation bandwidth can be estimated by closed-form formulas for each traffic class. We use ns-2 simulator to validate the analytical model. Some numeri- cal results are provided to evaluate the performance of EDCA. The numerical results demonstrate the corresponding effects for tuning different EDCA access parameters.

IEEE 802.11e EDCA(Enhanced Distributed Channel Access)는 서로 다른 AC(Access Category)에 따라서 CW(Contention Window)를 이용하여 Quality-of-Service(QoS)를 지원한다. 그러나 무선 네트워크 환경이 혼잡 (Congested)할 경우 패킷의 충돌 발생 확률을 높일 수 있다는 문제점이 여전히 존재한다. 이를 해결하기 위해 여러 방법들이 제시되었으나 혼잡 네트워크상에서는 동일 우선순위를 가지는 패킷 전송을 위해서 전송 채널을 이용하는 경쟁 과정에서 패킷 충돌(Collision)이 발생할 확률이 여전히 존재한다. 따라서 본 논문에서는 EDCA 포화 상태에서 전송 효율을 높이는 APCA(Advanced Priority Collision Avoidance) 알고리즘을 제안한다. 제안된 알고리즘은 IEEE 802.11e 표준을 기반으로 RTS/CTS (Request to Send / Clear to Send)를 이용하여 패킷 전송 FC(Frame Control) 필드의 예약된 필드(Reserved Field) 비트를 이용하여 데이터 패킷 충돌을 회피하는 것이다. 시뮬레이션의 결과로 제안된 알고리즘이 기존의 EDCA에 비해 패킷 전송 실패율이 감소했음을 보였다. Jain's fairness index를 이용하여 제안된 APCA 알고리즘이 네트워크 혼잡 상황에서 EDCA 방식 보다 공정성을 유지하는 것을 확인하였다. The Enhanced Distributed Channel Access (EDCA) function of IEEE 802.11e standard defines contention window (CW) for different Access Category (AC) limits to support Quality-of-Service (QoS). However, it have been remained the problem that the collision probability of transmission is increasing in congested network. Several different solutions have been proposed but the collision occurs among same priority queue within the same station to compete the channel access. This paper presents an APCA (Advanced Priority Collision Avoidance) algorithm for EDCA that increases the throughput in saturated situation. The proposed algorithm use reserved field's bits of FC(Frame Control) using IEEE 802.11e standard's RTS/CTS (Request to Send / Clear to Send) mechanism to avoid data collision. The simulation results show that the proposed algorithm improves the performance of EDCA in packet loss. Using Jain's fairness index formula, we also prove that the proposed APCA algorithm achieves the better fairness than EDCA method under network congested condition.

The Enhanced Distributed Channel Access (EDCA) mechanism is the most commonly implemented medium access scheme in today's wireless local area network (WLAN) products. With the introduction of the downlink multi-user MIMO (DL MU-MIMO) technology to the current IEEE 802.11 specification, the EDCA mechanism has been enhanced accordingly to support multiple simultaneous transmissions to different stations. In this paper, we report the work the IEEE 802.11ac task group has done for enhancing the backoff schemes of the EDCA mechanism and point out its issues. We then present two of our approaches which we believe perform better, in terms of fairness and network throughput, than the approach adopted by the current 802.11ac draft specification. OPNET simulations were conducted for performance evaluation.

The popular IEEE 802.11 WLAN today does not provide any quality of service (QoS) because of its contention‐based channel access nature of the medium access control (MAC). A simple software upgrade‐based solution, called a dual queue scheme, can be used to provide QoS to real‐time services such as Voice‐over‐IP (VoIP). The dual queue scheme operates on top of the legacy MAC. In this paper, we present a modified dual queue (MDQ) scheme by considering a practical implementation limitation. On the other hand, the emerging 802.11e MAC includes a contention‐based channel access mechanism, called enhanced distributed channel access (EDCA). Prioritized channel accesses are provided to different traffic classes under EDCA.In this paper, we comparatively evaluate the performances of MDQ and EDCA via simulations in terms of delay, jitter and throughput for various scenarios. We also compare the two access schemes when multiple transmission rates are used via rate adaptation mechanism for reliable transmission over erroneous wireless channel. The simulation results show that EDCA apparently provides a better performance in most situations. However, MDQ provides an acceptable performance close to that of EDCA so that it can be used when the EDCA is not available and/or the hardware upgrade to 802.11e is not desirable for the cost reason. Copyright © 2006 AEIT

This paper introduces a simple three-dimensional Markov chain model for the Enhanced Distributed Channel Access (EDCA) mechanism of IEEE 802.11e MAC under saturation condition. This new Markov chain model can be used to evaluate the throughput performance of IEEE 802.11e EDCA. This new model captures all of the major Quality of Service (QoS) specific features, namely Arbitration Interframe Space (AIFS), minimum contention window size, maximum contention window size and virtual collision, for the IEEE 802.11e EDCA mechanism and hence can provide a novel numerical approach to pick the set of EDCA parameter values to meet the QoS requirements. The results of our analytical model are then verified using simulations.